THE JUICE BOX HEAD PAPERS: PART ONE

Opening Whisper:  2019 was a “rebuilding year”, as my neurological health recovered from 2 years of unstable Intracranial Hypotension.  The lack of posts on Shuntwhisperer has been due to my…invalidity.   I’ve been hammering away at this for over a month, and with the Great Coronavirus Pandemic in full swing, I am pushing this into publication, warts and all.  Please forgive any errors, sophomoric media, or broken links.  I will get around to corrections and improvements.  I believe the sentiment and subject matter make themselves obvious and cannot wait any longer…

AN OPEN LETTER TO SHUNT PATIENTS AND THE DISCIPLINE OF NEUROLOGIC SURGERY REGARDING PERITUBAL SUBGALEAL CSF LEAKAGE – AN UNDERAPPRECIATED COMPLICATION OF SHUNT SURGERY

 

INTRODUCTION TO THE PROBLEM PERITUBAL LEAKAGE

In the Shuntwhisperer post “The Hole In My Head…”, I recounted my experience with a shunt complication known as Peritubal Leakage.  Peritubal leakage (aka “Juice Box Head”, as demonstrated in this brilliantly illustrative Spielberg-esque video) is the unwanted/unregulated leakage of cerebrospinal fluid between the outer surface of the proximal shunt catheter and the dural tissues pierced by the catheter.  This results in unintended and significant drainage of CSF from the larger subarachnoid space surrounding and supporting the brain, instead of intended shunt valve-controlled drainage from the ventricular reservoir of CSF inside the brain – the distinction of these different CSF reservoirs is very important.

CSF Reservoirs
Comparison of CSF volume of ventricles accessed by ventricular shunts vs. CSF volume of subarachnoid space subject to peritubal leakage

The result: lowered/unstable ICPs with associated neurophysiologic repercussions due to CSF overdrainage from the untargeted CSF reservoir around my brain.  I endured this condition for two years before Dr. Kenneth Liu diagnosed the problem.  In March 2019, he performed a revision surgery to “plug the leak”.  The improvement I have experienced has been so dramatic by orders of magnitude that I feel the need to share it with the Shuntwhisperer community, as well as the discipline of Neurologic Surgery.

An important observation:  the size of my ventricles never changed size despite signs of Intracranial Hypotension (see below under “…Consequences Of An External Communicating Hydrocephalus”).  This led to skepticism of my condition by neurologic physicians who view changes in ventricular size on MRI exams as an indicator of shunt function.  In hindsight, stable ventricle size would be an obvious finding since the CSF overdrainage I experienced was not from the CSF reservoir inside my ventricles and through my shunt, but rather from the larger CSF reservoior of the subarachnoid space around my brain through a leaking burr-hole.  Equally important is that my adjustable shunt valve had been set to its maximum of 200mm H2O as we “chased” my decline into unstable Intracranial Hypotension during the first 4 months postop.   Ironically, this action raised my ICP, making leakage around the proximal catheter the preferential route for drainage of CSF instead of the more resistant, higher pressure route of my shunt system.

Neuroradiologists, please take note:  Hypotensive Ventricular changes only occur due to CSF pressure changes inside the ventricles; leakage from a CSF reservoir such as a leaking lumbar puncture or, as in this case, a leaking burr-hole, may not result in changes in ventricular size, making MRI evaluation of shunt function suspect if a CSF leak is present.  Re-examination of my MRI from July 2018 actually revealed changes in signal density of the cortex of my brain (parenchymal thickening) “consistent with chronic intracranial hypotension/subarachnoid hemorrhage”.

Before continuing further, I need to emphasize a very important point:

Nothing I have experienced is the result of incorrect diagnosis, improper treatment, or poor surgical technique.   It appears instead to be an unintended outcome of the current state of evolving ICPDD shunt treatment protocols.  It is my hope what follows will be taken in the spirit intended, for the benefit of patients and surgeons alike: the potentially significance of an understandably small detail in the larger picture that has more significant ramifications than currently believed.

 

PERITUBAL SUBGALEAL LEAKAGE: ONE SMALL SURGICAL DETAIL WITH SIGNIFICANT IMPLICATIONS

Peritubal Leakage is significant due to its potential to interfere with maintenance of stable ICP. Unregulated CSF release out of the cranium independent of shunt management is known to exacerbate already dysregulated neurologic function and related symptoms.

CSF_ICP_SX
“MRI Abnormalities” are dependent on the CSF reservoir affected. Leakage from extraventricular sources may not result in changes in ventricle size; chronic subarachoid leakage will cause changes in the MRI signal of the cortical (outer) layer of the brain. Graphic courtesy of Medscape.com

Peritubal Leakage itself appears to be an underappreciated/currently unrecognized potential complication of shunt placement surgery and does not appear in lists of “common” shunt complications, though symptoms associated with unstable ICP do appear; in my case, these symptoms were described as “normal”.  I now know otherwise and hope to impress upon all involved the severity of this preventable/treatable condition.  Peritubal Leakage is the result of a “perfect storm” of the wound physiology of the transdural silicone/polyurethane proximal catheter and subcutaneous shunt system components.  Researching “Peritubal Leakage” led to several articles mentioning it as a potential complication of ventricular shunts as a secondary result of distal catheter occlusion, but not as a primary complication related to delayed bone healing of the burr-hole craniotomy – mine “appears” to be the first reported case.   However, searching the term “Subgaleal CSF Leakage” results in a plethora of publications describing CSF leakage/accumulation beneath the scalp as a result of both cranial trauma and surgery.  Based on my research, observations, and personal experience, I believe Peritubal Subgaleal CSF Leakage from the subarachnoid space is a significant contributor to “common” shunt morbidities due to resulting suboptimal ICP management.  This unstable ICP  exacerbates already dysregulated neurologic  function as shown in the Medscape graphic above.  There is, however, a very bright spot: Peritubal Leakage is readily treatable, and more importantly, preventable using proven wound management techniques employing readily available materials in the neurological surgery suite.  Further, prevention of this complication is very low cost in terms of time and expense by making a simple modification to current shunt placement protocols.

PERITUBAL SUBGALEAL LEAKAGE:  THE PRECEDENT OF SUBGALEAL SHUNTS

The hallmark clinical sign of peritubal leakage I experienced was regular, periodic (over the course of several hours) visible and palpable swelling along the tract of my shunt system.  These episodes of swelling corresponded to increased relative ICP dynamics and were accompanied by tingling/itching of the scalp on the entire right side of my scalp. They persisted until ICP dynamic changed and CSF was resorbed into the tissues of the scalp.  Below are photos taken hours apart on the same day demonstrating this condition (hover cursor over photos for captions) :

The swelling  in the right photo is accumulation of CSF in the subgaleal layer of my scalp tissue originating from the burr hole where the proximal catheter of my shunt system enters my cranium..  The Subgaleal Layer is loose areolar connective tissue just above the bone of the external surface of the cranium, both binding the scalp to bone while allowing a degree of mobility of the overlying skin:

subgaleal space
Subgaleal Connective Tissue Layer and Space of the Scalp

As previously mentioned, there is scant information about Peritubal Leakage; however, much can be inferred from an accepted type of shunt employed in neonatal hydrocephalus patients known as a Subgaleal Shunt.  Subgaleal shunts relieve pathologic ICP without subjecting the neonate/infant to additional surgical stresses and growth considerations of draining CSF into the abdomen.  These shunts “simply” route a proximal catheter from an intracranial CSF reservoir into the subgaleal space before being ultimately absorbed by surrounding blood and lymphatic tissues of the scalp.  No shunt valves; tension of scalp tissues serve as the limiting factor of CSF drainage, along with direct taps of the shunt reservoir as needed.

Distention of the scalp due to CSF forced out of intracranial spaces under ICP can be significant but are normal in this type of shunt system used in newborn infants.   However, for an adult patient with a VP shuntperiodic swelling along the shunt system tract constitutes a red flag of uncontrolled CSF leakage into the subgaleal space.  Swellings that persist for more than a day may be a sign of a subgaleal hematoma, a collection of blood beneath the scalp that could indicate bleeding inside the cranium which requires immediate medical attention.

 

PERITUBAL LEAKAGE: CAUSALITY

Peritubal Leakage is the predictable result of shunt treatment based on the physiology of the surgical wound created in the cranium for introduction of the proximal catheter of ventriculoperitoneal/ventriculoatrial shunts.  This may also apply to lumbar shunts as well; however, I will restrict this post to VP/VA shunts and my understanding of currently accepted surgical procedures, very briefly summarized here:

  • Scalp flap incision and reflection:
  • Burr-hole/craniotomy: a surgically created bone wound performed for the purpose of exposing the dural lining of the brain to allow insertion of the proximal shunt catheter into a ventricular CSF reservoir inside the brain.  Creation of  the burr-hole must be performed with care to prevent pushing bone fragments into the cranium and/or tearing the dural tissue immediately beneath (Having performed many surgeries in nasal sinuses, I know from experience, this is delicate.  Think of removing the shell from a boiled egg without tearing the inner collagen membrane, a membrane that varies in consistency from tissue paper leather amongst various patients).  The diameter of the burr hole is approximately 15mm/0.6in.  (The average thickness of the adult human cranium is about 6.4mm/.25in; thus, the resulting bone wound in the cranium is ~2.5 wider than it is deep.  This is important in determining how the bone wound will heal without intervention as will be explained shortly.)
  • Placement of the proximal catheter through the dura, across the subdural space (containing CSF) around the brain, through the frontal lobe of the brain, targeting the Foramen of Monro at the base of the third ventricle inside of the brain. This is accomplished via real-time 3D guidance via Medtronic’s brilliant Stealth System, shown in this video:
  • The distal catheter is routed to its terminus equally brilliantly via subcutaneous tunneling, shunt valve(s) are connected with catheters, and the system checked for integrity, all very delicate tasks that require attention and time.
  • The scalp flap is repositioned and secured with sutures/staples.

 

THE BURR-HOLE PROBLEM

This bone wound in the cranium is a small but very, very significant in terms of its size, shape, and presence/composition of the proximal catheter:

1317_CFS_Circulation(1)
Intact cranium
Dural Bulge at Burr-hole
Removal of cranial bone results in lack of support of dura; CSF under ICP bulges dura outward
1317_CFS_Circulation(1) proximal catheter
Subarachnoid CSF Leakage
Unhealed Craniotomy
MRI demonstrating my CSF leak

 

 

Early wound physiology begins to demonstrate a potential problem with the transdural proximal catheter.  Shunt catheters are 4.0mm in diameter with 1.5mm inner lumen for CSF drainage.  They are made from a very flexible silicone or electrospun polyurethane-based material which are treated to prevent adhesion of clumps of cells to the inside of the catheter.  These adhesions can potentially obstruct the catheter resulting in shunt system failure.  The anti-adhesion quality of these components also prevents cells from adhering to its outer surface.  This means that neither collagen based dural tissue nor cranial bone adheres to the proximal catheter during healing. Examination of the transdural proximal catheter reveals that the collar of dural tissue around the catheter is no longer supported by bone;  as such, it cannot resist the outward pressure of CSF caused by ICP (Monro-Kellie Violation).   As a consequence, cerebrospinal fluid in the subdural space under sufficient intracranial pressure can displace the unsupported edges of the dural wound outward like an organic juice-box valve, allowing CSF to escape from the subdural reservoir and accumulate along the tract of the shunt system.  The visual analogy I prefer is how juice escapes around the straw of a juice box/pouch when squeezed, hence the moniker “Juice Box Head” to describe Peritubal Leakage.

Mathematical analysis of this condition reveals that the area perimeter of the 4mm catheter is an order of magnitude larger in potential volume than its 1.5mm inner lumen.  The inner lumen of the proximal catheter has a fixed cross sectional area of 1.76mm2. The same catheter’s 4.0mm outer diameter surface area is 12.56mm2.  if the dural edge is displaced by CSF under the influence of ICP by 0.5mm, the total area for potential leakage around the periphery of the catheter nearly matches the internal lumen area where CSF drainage is intended to occur under the control of the shunt valve.  If the dural tissues yield at ICPs lower than the opening pressure of the shunt valve, CSF will preferentially leak around the proximal catheter from the subdural CSF reservoir instead of the intended ventricular reservoir.  This process is the basis for the development of unstable ICP as well as transition from Intracranial Hypertension to Intracranial Hypotension as I discovered.

Current standard neurologic surgery protocols focus on the demanding tasks of opening the patient’s cranium, placement of the shunt catheter through the brain into the desired ventricular CSF reservoir, and routing of the distal catheter to drain CSF into the desired body cavity.  There is no standard protocol to address the small but very significant bone wound created by the craniotomy – it is left to “heal on its own”, an oversight which I contend is in contravention to known wound physiology.  Bone defects heals very slowly, at a rate of 100-200 microns (um) per day.  New bone grows from the blood supply of existing living trabecular bone; thus, the circular craniotomy heals from the edges towards the center (seen in the video of serial CT/MRI scans of my craniotomy).  Using these facts, it can be seen that it would take this 15mm/15000um wound between 10 and 20 weeks to heal with bone.   The discipline of Orthopedics tells us that the time required for a bone wound to heal to 70% density is 16 weeks (Human Bone Sigma Healing).

However, bone is not the only tissue actively growing in a healing wound: soft tissue (proliferative collagen, aka “scar tissue”) can – and does- preferentially invade the volume of a wound previously occupied by bone at a rate of 1000-2500um (1-2mm) per day, 10 times faster than the slower growing bone (osteoid  tissue, which begins as a soft tissue that later becomes infused with calcium in a form known as hydroxylapatite.  Once non-bony soft tissue organizes in a wound, bone formation is precluded from that volume of the wound.  In the case of our circular craniotomy, this is aggravated by the invagination of the scalp flap into the craniotomy, creating a dimple into the wound volume which was occupied by cranial bone pre-surgically.  Further aggravating this undesirable condition are the dimensions of the burr-hole, or rather the ratio of its diameter to the thickness of the cranium: at ~2.5 times as wide as it is deep, even this small wound becomes subject to immutable laws of bone healing.  Its shallow, wide shape predisposes it to soft tissue invasion as well as invagination of the scalp tissue into a volume once occupied by bone.

The result is a transdural silicone catheter surrounded, at least in the early weeks of healing, by “loosely organized” dural collagen and soft/scar tissue.  There is no actual “seal” of dural tissues to the outside of the catheter because cells cannot adhere to the silicone/polyurethane catheter.  The integrity of the bony cranium is compromised by the craniotomy, and as I discovered, can lead to significant morbidity if intracranial pressures are sufficient to cause CSF to seep between the outside of the catheter and attached shunt system components.  This chain of surgically implanted shunt components creates a potential reservoir in the subperiosteal/subgaleal space, allowing CSF seeping around the proximal catheter to accumulate around the shunt system  outside of the cranium creating the aforementioned subgaleal hygroma.  Below is a a video of images and models taken from serial CT/MRI scans taken at postop, 3 months+++++++demonstrating this exact series of circumstances that caused my unstable shunt treatment: a transdural catheter, lack of bone to support the dural tissues at the outer perimeter of the catheter, and the late bone healing pattern of the burr-hole craniotomy

 

PERITUBAL LEAKAGE: CONSEQUENCES OF AN EXTERNAL COMMUNICATING HYDROCEPHALUS

Peritubal Leakage caused me to transition from Intracranial Hypertension (intolerance of upper limits of my ICP physiology) to unstable Intracranial Hypotension.  Having experienced both ends of this spectrum, I can say each has its own unique “misery index”.  I can further testify as to how unstable Intracranial Hypotension limits functional capacity by orders of magnitude.  Here is a brief summary of the most severe symptoms I experienced:

  • Subgaleal Hygroma: Regular periodic swelling, both palpable and visible, along shunt tract beneath scalp with accompanying increases in barometric pressure AND/OR systemic blood pressure/heart rate dynamics. These episodes of swelling were accompanied by soreness and tingling of my scalp three to four inches around my shunt components, with occasional crepitus (crackling sensation of skin when touched due to fluid accumulation).
  • MRI/CT evidence of transition to Intracranial HYPOtension: these findings are NOT restricted to changes in ventricular size, and instead may be evidenced by changes in the signal of the outer cortex of the brain.  Shunt settings and individual patient physiologies may show different combinations of these findings, and subjective patient symptoms MUST be given credence when they seemingly conflict with objective test results.
  • Severe Intolerance to barometric pressure changes related to weather.***
  • Intolerance to prolonged (24-36h) of barometric pressure below 950 mb, with accompanying symptoms:
    1. Extreme fatigue, frequently requiring bed “rest”
    2. Increased fibromyalgia pain
    3. Cognitive challenges including impaired problem solving, depressed mood/labile emotions
    4. Aggravated level of tinnitus during periods of perceived low ICP, compared to pulsatile tinnitus during periods of perceived high ICP.
    5. Changes in vision out of right eye (my “migraine side”) from day to day manifesting as changes in near vision accommodation
    6. Over the course of two years, the development of apparent autonomic and neuroendocrine dysfunction manifesting as the Hyperadrenergic form of POTS as well as exercise intolerance/muscle wasting presumably related to HPA axis dysfunction (I show evidence of Empty/Partial Empty Sella Syndrome which developed only after the onset of Intracranial Hypertension).

This list is short and does not delve into further subcategories at this time, some of which are very significant.  As noted in the title, this is “Part One”.

 

THE SIMPLE SOLUTION TO PERITUBAL LEAKAGE: GUIDED TISSUE REGENERATION

Guided Tissue Regeneration (GTR) is a surgical process originating in Orthopedics research in 1959:

  • Hurley LA, Stinchfield FE, Bassett AL, Lyon WH (October 1959). “The role of soft tissues in osteogenesis. An experimental study of canine spine fusions”. The Journal of Bone and Joint Surgery. American Volume. 41-A: 1243–54. PMID13852565.

GTR is used extensively in orthopedics, oral surgery, and  neurologic surgery to exclude soft tissue from a bone wound, as well as enhance bone volumes in areas so desired.   In my dental practice, I personally employed GTR as part of oral surgical procedures to ensure adequate bone volume and quality in the desired location of dental implants, as well as to regrow bone lost due to disease, pathology, or trauma.  GTR is beginning to become a topic of discussion in neurologic surgery as well, and after my experience, I can say it cannot come fast enough.

GTR facilitates desired bone growth by a twofold approach.   First, a biocompatible/bioactive grafting material is placed into a bone wound.  The grafting material “holds space” into which new bone to heals after graft material is resorbed during normal healing, ultimately being replaced with the patient’s own bone.  In some cases, vital bone is grafted from one part of the patient’s body to the desired site, but the healing process is still the same, even with vascularized grafts.  Calcium sulfate, essentially medical grade bioenhanced plaster, is a popular, effective, and inexpensive option for this size defect.  Newer materials are becoming widely accepted that may prove even more effective and will be the topic of another post in this series.

The second part of GTR is a “bone bandage”: a biocompatible membrane placed over the graft site (in this case, the burr-hole craniotomy) which excludes unwanted soft tissue from the bone wound.  This “bone bandage” is known as a guided tissue membraneGuided tissue membranes need to be biocompatible and must persist in the surgical wound long enough for osteoid tissue to form, preferably a minimum of 8 weeks.  These membranes are made from various materials; a very short list includes PTFE (aka “Teflon”), cross linked bovine collagen, and titanium in the form of foil and thin plates.  Some membranes such as those made from collagen are dissolved by the body over time; others such as Teflon and titanium persist.  Each has its unique pros and cons depending on the application, and in this particular application, I personally see titanium plates as the clear choice: the combination of calcium sulfate and titanium offer immediate dural support from postop through burr-hole healing with bone. Examples of these readily available materials in a neurologic surgery suite are shown below:

 

In the revision surgery which has literally given me my life back, Dr. Kenneth Liu revised my original shunt with the goal of sealing the unhealed and leaking burr-hole.  This was performed March 2019, almost exactly 2 years to the day Dr. Liu had placed my original shunt.  He removed/debrided the soft tissue that had formed in my burr-hole (preventing bone healing) and created bleeding points at the periphery with the surgical equivalent of a Dremel tool (remember: new bone grows from the blood supply of existing bone).   A groove was created in the edge of the craniotomy for the proximal catheter to lie in. The burr-hole defect filled the resulting wound with bioactive calcium sulfate (bone “plaster”) and covered the craniotomy with a readily available stock round titanium bone plate that, when screwed into place, extended beyond the edges of the craniotomy.

Dr. Liu also replaced my Sophysa Polaris shunt valve with a Meithke ProGav 2.0 valve, not because the Sophysa was suspected of being defective (Sophysa has an outstanding record of reliability), but because the newly available Meithke ProGav offered a greater degree of opening pressure adjustability, not to mention being much a much smaller size.   Dr. Liu’s Facebook page has this picture of what may be my actual valve, giving an idea of its size, the approximate equivalent about of three quarters stacked atop one another:

My ProGav
(My?) ProGav 2.0 Shunt Valve from Dr. Liu’s FB page

This valve is adjustable in “infinite” increments over its 0-200mm H2O pressure rating using external magnetic tools, is MRI resistant to 3T (I can vouch for both the Pro-Gav and Sophya valve’s resistance to MRI fields).  Further, the Pro-Gav’s low profile has significantly improved comfort as well as not being as visibly apprarent with my “high and tight” hair…style.

From the first moment I remember postoperatively after revision surgery, I could feel enormous improvement.  The best description I can offer is that I actually had a “normal” pressure in my head, as opposed to an “empty” sensation.  This has only improved in the last year.  Some of the improvements I notice are:

  • Barometric pressure sensitivity: prior to the revision, I was a puppet to the weather as well as altitude.   This problem was so severe that I could not live at my home located at a modest 2200 feet above sea level, nor could I tolerate barometric absolute pressures (station pressures***) below 950mb.  I was a geographic hostage, a medical gypsy forced to relocate to lower elevations/higher barometric pressure areas almost weekly for relief.  Low barometric pressures due to weather or altitude would cause me to experience extreme fatigue.  As mentioned in “The Hole In My Head…”, I consulted with Dr. Liu to procure a home hyperbaric chamber to prove to myself and to Dr. Liu that my extreme sensitivity to normally tolerable environmental changes was real.  Post-revision, I have been from sea level to as high as 4000+ feet without any noticeable deleterious effects.   At the time of this post, the current station pressure is 918mb, and aside from a predictable mild morning migraine, I’m functional, whereas prior to the revision, I would be confined to bed and very lethargic.
  • Immediate 99% reduction in Peritubal Leakage: my craniotomy is by now healed with my own bone beneath the titanium plate.  This bone does not adhere to the proximal catheter,  but it does provide enough added resistance to dural displacement and unwanted CSF leakage around the catheter that 99% of the time I cannot appreciate any CSF accumulation as evidenced by tactile/visual swelling along the shunt system.  I no longer experience any swelling along the shunt components,  which now feel as if my scalp has “vacuum formed” over them. Occasionally there is a very, very small accumulation of CSF along the catheter at the edge of the plate, but it is not visibly evident, only noticeable by telltale slight tingling of the adjacent inch or so of scalp – greatly reduced from pre-revision conditions.  Best of all I do not have the symptoms of Intracranial Hypotension that previously accompanied the degree of peritubal leakage previously demonstrated.
  • Slow but steady improvement in neurologic functions:
    1. Exercise intolerance: pre-revision, I was pathologically intolerant of any degree of exercise and was becoming severely deconditioned.  Stairs were becoming a problem.  Now, I tolerate reasonable amounts of physical activity and light exercise with normal recovery as opposed to the week of intolerable pain that previously resulted from any exertion.
    2. Pain Level: 90% improved, and not a moment too soon.  Fibromyalgia pain is linked to Intracranial Hypertension. I can say with absolute certainty that Intracranial Hypotension made my fibro pain as bad, if not worse, than Intracranial Hypertension.  Let me be clear, both were severe and varied only by levels of misery.
    3. Functional Capacity: I was essentially a low-functioning invalid pre-revision.    I am now able to live independently in a manner consistent with a 59 year-old male with an Intracranial Pressure Dysregulation Disorder.  I enjoy several hours of function a day, whereas pre-revision, I would be bedridden for 3-4 days at a time for every “good” day I had out of bed.  I’m somewhat ashamed to say that the lack of posting on Shuntwhisperer has partly been because I’ve been actually able to get out and have a life.
    4. Improved Cognitive Function: Goodbye, Brain Fog, memory lapses, and the inability to perform simple math in my head.
    5. Improved sleep – prior to revision, sleep had become increasingly poor, with frequent episodes of waking at night with my heart pounding out of my chest for no apparent reason. I believe I was experiencing episodes of breathing patterns similar to Cheyne-Stokes due to aggravation of low ICP at night.  I required CPAP and supplemental oxygen, but no longer need them.  Mornings no longer involve an hour of misery/agony that persisted until I consumed enough caffeine to raise my ICP; these episodes would stop at about the same time I could detect flow in my shunt system.  (note: shunt-assist related nocturnal overdrainage will be covered in a separate post)
    6. Improved emotional health: though I had learned to cope with the ups and downs that seemed to accompany swings in ICP, it was exhausting. This too has improved by orders of magnitude, and I rarely find myself forced to evaluate  seemingly irrational emotional states for validity.

 

DISCUSSION

First of all, my heartfelt gratitude to Dr. Kenneth Liu, most recently practicing at Penn State/Hershey Neurologic Services, for his support and willingness to make this improvement possible.  Dr. Liu, sincere thanks.

It took nearly 18 months to deduce that I was experiencing Peritubal Leakage, another 6 months before it was able to be corrected.  I will summarize the experience in technical terms: pure, absolute hell.  The condition I was experiencing was an uncontrolled CSF leak via an unintentional, surgically created, external communicating hydrocephalus.  Reviewing how this leak likely occurs: the dural wound around the proximal catheter lacks the rigid support of the cranial bone removed during shunt placement surgery.  ICPs exceeding the ability of elastic dural tissues to seal against (not “to”) the proximal catheter allowed CSF to seep out from the subarachnoid space, around the outside of the catheter between the catheter wall and edges of the dura.   The leaked CSF pooled along and around the components of the shunt system (catheters, shunt valve, shunt assist valve), resulting in noticeable periodic swelling of the scalp as shown in photos/video.  At the time, the opening pressure of my system was 200 to 450mm H20*.   In my case, it is likely that peritubal leakage occurred at ICPs below the opening pressure of the shunt, creating an “overdrainage” scenario similar to a shunt system set at too low of an opening pressure.  However, CSF leakage likely occurred from the undesired subarachnoid reservoir of CSF around the brain.  This is a much larger CSF reservoir than the intended third/lateral ventricles and thus not as self-limiting nor regulated by the shunt valve(s).  The volume of CSF in the subarachnoid space directly affects brain buoyancy as well as neurologic function.  I exhibit borderline Chiari 1 imaging when lying flat; a reduction in brain buoyancy would theoretically aggravate impingement of my foramen magnum by my cerebellar tonsils.  Further evidence supporting this theory is that while I exhibited symptoms of Intracranial Hypotension, the size of my ventricles remained stable over 2 years, indicating the shunt system was not responsible for the “overdrainage” because unwanted CSF loss was not coming from the ventricular reservoir, but rather the larger subdural reservoir.

As mentioned previously, I have experienced improvement in neurologic and emotional health that are literally orders of magnitude better than when I was experiencing PT.  Some of those improvements happened immediately; some of them have taken months.  Dr. Liu had a term: “Angry Brain Syndrome”, describing dysfunctional neurologic health caused by pathologic ICP dynamics.  The term has proven to be very apt.  And, while I endured significant difficulty for two years, I am now enjoying dramatic and continuing improvement as a result.

 

NEUROLOGIC SURGERY: A PROPOSAL TO MAKE A SIMPLE IMPROVEMENT

Pointed Statement Alert: by now I’m certain I’m not the only one who has or will experience negative impact on already impaired neurologic health due to Peritubal Leakage.  I’ll stop short of saying  peritubal leakage is nearly universal, but current shunt surgery protocols as described make it potentially possible in every patient if the burr hole craniotomy is not addressed with Guided Tissue Regeneration.   I have spoken with two neurosurgeons about the following proposal and have been greeted with “we don’t see peritubal leakage as a problem”.  Respectfully, as the surgeon and not the patient, that statement carries little validity when viewed in the dichotomy of subjective findings and objective experience, especially when based on known wound physiology as I have described.  The impact on patient function of this issue is inarguably quite significant, thus I recommend that the belief that Peritubal Leakage is “not seen as a problem” needs to be revisited.

Based on my surgical training and experience, knowledge of bone wound physiology,  not to mention my “experienced based residency” as a shunt patient, I can say with absolute certainty  that peritubal leakage potential carries a significant negative impact on the stability of intracranial pressure dynamics, and by extension, neurologic health.  My condition was ultimately and dramatically improved by a second surgical intervention and the employment of a well-understood wound care process known as Guided Tissue Regeneration.  The magnitude of that improvement has been literally the difference between having a modicum of function vs. being bedridden and essentially nonfunctional every time the weather changed or I just went to my home at the “dizzying” altitude of 2200 feet.  As such, I propose that Guided Tissue Regeneration repair of burr-hole craniotomies be considered a standard practice in VP/VA shunt surgery at initial placement using bioactive calcium sulfate and titanium plating.  I further propose that patients exhibiting signs of subgaleal hygroma be evaluated for peritubal leakage through CT/MRI imaging of bone healing of the burr-hole craniotomy, signs and symptoms of Intracranial Hypotension, with due consideration given to GTR revision/valve revision in cases of poor/delayed bone healing of the initial burr-hole craniotomy.

The addition of this extra measure necessarily requires an evaluation of the cost, time, and risk/benefits of a GTR repair of a craniotomy, and from every standpoint, pros outweigh cons in every category.  First, flap design needs to consider adequate wound margin from the titanium plate covering the craniotomy.  Next, materials: standard armamentarium of the neurologic surgical suite reveals that integral materials and components, chiefly bioactive calcium sulfate (with metronidazole/rifampin added)** and “stock” circular thin screw retained solid (not mesh) titanium bone plates, similar to those shown above. Surgical time is estimated to be 15-20 minutes at most during initial implementation to create a groove at the distal edge of the burr-hole for the proximal catheter to lie in,  preventing its impingement by the edge of the bone plate, followed by placement of the calcium sulfate, and fixation of the bone plate, preferably before final set of the calcium sulfate graft**.  At this point, repositioning and closure of the flap would proceed as normal.  Scalp invagination and soft tissue migration into the burr-hole/craniotomy would be effectively precluded.  The patient’s healing physiology will dissolve the calcium sulfate and replace it with their own bone over 4-6 months.  Cost of the bone plate and calcium sulfate, while not inexpensive, are comparative pennies (less than $1000 billable) compared to the cost of shunt placement surgery ($75,000+ for the my first shunt, $28,000 for the revision).  I would go so far as to consider billing these items at cost due to the critical nature of their role in enhancing wound healing and mitigating unpredictable leakage and suboptimal patient experiences as a result; in reality, “billing at cost” is becoming an unfortunate standard not only in Medicare/Medicaid, but private insurance plans as well.  But, losses here can be made up on volume (sad but true medical humor).  The true cost savings of adding Guided Tissue Regeneration to shunt placement surgery is the incalculable cost of improved treatment outcomes and reduction in monetary and risk costs of revision surgeries to correct the previously unrecognized consequences of Peritubal Leakage.

There is no apparent predictor for the incidence and degree that peritubal leakage will occur in a shunt craniotomy, but known wound physiology supports its likelihood.   Improving the seal around the transdural proximal catheter by ensuring ideal bone regrowth with Guided Tissue Regeneration at the time of shunt placement makes good surgical sense and is ultimately in the best interest of patient and surgeon alike.   Guided Tissue Regeneration is a refined field that extends back 35 years; the process I have described of using bioactive calcium sulfate and a non-porous titanium plating is a GTR process that has stood the test of time.  Therefore, I propose that Guided Tissue Regeneration be considered a standard practice in VP/VA shunt surgery at the initial surgery.

**Check back for an upcoming post: “Platelet Rich Fibrin: beyond Calcium Sulfate” 

 

 

UNDERSTANDING “IIH” – FAQ’S

“(the cranium is) Just like carry-on luggage, only so much can fit…one pair of socks to many, and the seams start to strain.”

I’ve only lived with IIH for a few years – much less time than many, many others I encounter in support forums.  Lately I’ve taken notice of newly diagnosed patients who seem to be as perplexed at the lack of information and explanation of their condition as I remember being in 2017 when I was told “Nobody knows nothing about IIH.” (paraphrase). 

Judging by the bewildered posts of new members of our auspicious group, there hasn’t been much change.

What follows is the beginning of a “Frequently Asked Questions” section of Shuntwhisperer.  The information here is a combination of 1) my personal experience, observation of others with IIH/PTC/ETC, 2) published research that is fairly abundant for a disorder that seems to amount to a Black Hole of Understanding, 3) readily accepted tenets of human physiology, and 4) the babblings and savante-garde notions of a guy with a hole in his head and a tube in his brain.

Fair warning, take it for what its worth ; )

In all seriousness, I pray this helps those seeking answers, and as always, it’s not about me being right, it’s about getting others to think and talk about IIH in the hopes that this dialog will spark understanding and improved quality of life for everyone. 

Thus, with the timelessness of the inspired dialog of Shakespearean-trained actor Patrick Stewart,

“ENGAGE!”

 

FREQUENTLY ASKED QUESTIONS ABOUT IIH

Short Answers First, Technomedical Stuff Second

WHAT IS “INTRACRANIAL HYPERTENSION”?

Short Answer:

“Intracranial Hypertension”, or “IIH”,  is one name for a group of complex disorders in which an individual develops physical signs and symptoms caused by abnormally high pressures of the fluids in and around the brain.* 

 

Geek Stuff:

The adult human brain is enclosed in a protective bony compartment of the skull known as the cranium.  The main contents of the cranium are the brain, connective tissue (meninges), and two fluids: blood and cerebrospinal fluid (CSF).

Because the cranium is rigid and has a fixed volume, net accumulations of either fluid will increase the pressure inside the cranium (Intracranial Pressure, or ICP).

“Intracranial Hypertension” results when an individual’s tolerance for normal pressure variations becomes compromised, especially high pressures.  These pressures can affect the brain itself, becoming stressed with predictable results   It is referred to by several abbreviations which likely represent individual variations of the same “disorder”:

  • IIH – “Idiopathic (‘of unknown origin’) Intracranial Hypertension
  • NPH- “Normal Pressure Hydrocephalus” –  A very misleading term that is contradictory and would only apply to true conditions of hydrocephalus, a condition where Cerebrospinal Fluid becomes trapped due to developmental or traumatic factors, allowing the very slow forming CSF to accumulate in isolated areas under significant pressure, causing deformation and/or damage to the brain tissue
  • BNPH- “Benign Normal Pressure Hydrocephalus” – Another extremely misleading term, as with “NPH”, along with the fact it is anything but “benign” (harmless)
  • PTC – “Pseudotumor Cerebri” – literally, “false brain tumor”, one of the earliest names given to this class of disorders due to the fact that a patient’s symptoms usually mimic those of a brain tumor, but upon CT/MRI, no tumor is evident.

I consider these “different” diagnoses to be representations of a similar disorder, expressing itself differently in individual patients due to their particular physiology.   Consequently, I refer to these disorders as Intracranial Pressure Dysregulation Disorders, or ICPDDs.

427420290-cerebellar-vermis-metencefalon-cerebral-hemisfere-brain-lobe
The Brain and its supporting anatomical structures are encased in a rigid bony protective compartment of the skull known as the cranium.  Just like carry-luggage, only so much can fit inside.  One pair of socks too many, and the seams start to strain.

*Growths of soft tissue such as tumors and cysts may also increase ICP with similar presentation; however these conditions fall into different diagnostic and treatment categories.  For the purposes of discussing the ICPDDs, the focus will be on blood and cerebrospinal fluid, assuming there are no abnormalities of the soft tissues in the cranium, including the brain itself. 

 

WHAT IS THE SOURCE OF “INTRACRANIAL PRESSURE”?

Short Answer:

Intracranial Pressure, or ICP, is the created by high volumes of blood being pumped into an extensive network of blood vessels that support the brain. (This is the foundational principal of Intracranial Pressure Dynamics, hence my appellation “Cerebrovascular ICP Dominance Principal”).**

Geek Stuff:

The brain requires more energy than any other organ in the human body.  That energy is delivered by blood containing oxygen and glucose.  Blood also carries away metabolic waste from brain cells (neurons).

  • Big Numbers Alert: The adult brain has an estimated 100 billion cells called neurons.  Getting blood to each neuron requires a vast and intricate network of blood vessels estimated to be up to 100,000 miles in total length.  The majority of the vessels are so small that blood cells must pass through one at a time.

Blood enters the brain through arteries under high pressure (Average Mean Arterial Pressure of 90 mm Hg) and volume (750-1000cc per minute).  Resistance to the flow of viscous blood (~1.8 times “thicker” than water) through the network of vessels creates pressure in the vessels.  This pressure is transferred from the blood vessels to the brain tissue and ultimately into cerebrospinal fluid in and around the brain and spinal cord, creating what is termed “Intracranial Pressure.”

**Shortly after arriving at and naming this principal “Monro-Kellie 2.0” in Millennial TechnoEvolutionary Credit to the Monro-Kellie Principal, I discovered a cheeky neurosurgeon of “Her Majesty’s Royal College of Medicine, London” had published a paper on this very subject in 2016.  His name is Wilson.  Dr. Mark Wilson.  His publication:

Monro-Kellie 2.0: The Dynamic Vascular and Venous Pathophysiological Components of Intracranial Pressure

This publication, accurate and well written, was obviously composed by MI6 as cover for “Dr. Agent” Wilson.  Subterfuge aside, it does make both Agent…excuse me, Dr. Wilson and myself seem like a pair of bright bulbs.  Nonetheless,  a pair of very stiff upper lipped chaps suggested I change the name by which I referred to this principal, in the name of the Queen…and my kneecaps.

And I do favor mine very, very dry, and of course…

Shaken…not stirred.

XE3_00992_XL
“Dr.” Mark Wilson, Neurosurgeon

 

WHAT IS “NORMAL” INTRACRANIAL PRESSURE (ICP)?

Short Answer:

Intracranial Pressure is not a fixed, unchanging value.   ICP is dynamic by virtue of its origin in the volume and pressure of blood flowing into the brain, which is in turn inside of the rigid cranium with a limited amount of available space.  Factors affecting systemic blood pressure and an individual’s response/reaction to those factors, will cause ICP to vary as well.  “Normal” ICP is a patient-specific range of pressure determined by individual physiology.  Thus, for each of us, “Normal ICP” is any pressure that allows healthy & asymptomatic brain function.

Geek Stuff: 

While scientific studies establish an average of 110 mm of water (defined as the pressure at the base of a water column 1mm in diameter and 110mm tall), the truth is that “normal” ICP varies from person to person, again for reasons of individual physiology.  Furthermore, ICP varies in an individual over periods from as few as a few minutes to as long as years as dynamics of blood flow and CSF production fluctuate.

All aspects of ICP are dependent on the fact that blood is the only fluid that enters the cranium/brain.  Therefore the pressure and flow of that blood directly affect ICP, and hence the fact that an individual patient’s ICP varies within a personal range and is not a static value.

Finally, the brain itself ensures it receives adequate nutrient-rich blood, controlling blood flow through heart rate/contraction, as well as other critical factors including systemic blood pressure, available oxygen in the air (partial pressure of oxygen), a patient’s lung health (presence/absence of fibrosis, COPD, smoker, and other factors that affect gas exchange with blood in the lungs), health of the blood (anemia, hemoglobin, age/size of blood cells), as well as environmental factors including barometric pressure (and hence altitude), heat, humidity…the list goes on.

In a word, any condition that potentially hinders a person’s brain from getting adequate oxygen in the smallest quantity of blood possible, or which makes their tolerance for ICP fluctuations more narrow, or changes the dynamics of those fluctuations to higher ranges for longer periods potentially predisposes them to developing an ICPDD.

Mayfield-Clinic-Pic
Chiari Malformations are essentially brains too big for the available cranium…or vice versa.  The result is less available volume to allow a patient to tolerate ICP fluctations, not to mention the potential interruption of CSF circulation between the cranium and spinal cord, aka “corking” (credit to Dr. Diana Driscoll and her ongoing body of work, “The Driscoll Theory”)

See FAQ Topic “HOW DOES ICP BECOME ELEVATED?” (coming soon to a url near you! 7/30/2019)

 

WHAT CAUSES ICP TO BECOME ELEVATED?

(That was fast!)

Short answer: too many socks in the carry-on luggage.

The adult cranium is a rigid bony case and does not expand or contract. After the bony plates of the skull fuse in adulthood, it has a defined available volume.  If one or more of the contents of the cranium accumulates without a matching decrease in the other contents, the pressure within the cranium predictably increases.*  For the purposes of discussion of ICPDDs, blood and cerebrospinal fluid (CSF) will be the only cranial contents considered to affect ICP.  Growths of soft tissue such as tumors and cysts can also increase ICP, however these conditions generally fall into different diagnoses and treatments.

Looking at blood and CSF, it becomes apparent that blood is the dominant, driving force behind ICP:

  • Blood is the only fluid to enter the cranium, at a rate of nearly one liter per minute at rest, a figure that represents approximately 20% of cardiac output.  This is because the brain demands enormous quantities of oxygen and glucose to function, and actively regulates the amount of blood it receives in real time.
  • By contrast, Cerebrospinal Fluid (CSF) is a by-product of brain function.  It is “distilled” by osmosis in specialized cells lining small hollow (normally) interconnected areas within the brain known as ventricles, as well as by similar tissue along the outside of the brain.  It is produced at a mere 0.35cc/minute from arterial blood, and as such accounts for only 0.0004% of the fluid dynamics within the cranium, with blood accounting for 99.9996%.
  • Blood and CSF are both present in the cranium in approximately equal volumes of 150 cc.  The blood volume enters and exits at approximately 6-7 times per minute; CSF is produced and replaced approximately every 7 hours.
  • CSF flow passively in and around the brain, following pressure gradients from areas of production to areas where it is absorbed by veins and lymphatic tissue.  This passive circulation is aided by pulsations of blood vessels in the brain as well as physical movement of the body.

ICP becomes elevated if blood and or ICP accumulate at a greater rate than they are removed from the cranium.  Due to the high flow rate of blood into the brain, even the smallest deficit in drainage of blood from the brain becomes a potential source for rapid elevations of ICP; this is known as (Chronic) Cerebrospinal Venous Insufficiency, or CCSVI, but could more accurately be termed Cerebrovascular Outflow Insufficiency, Acute and/or Chronic.  This is likely the source of elevated ICP in patients who do not have isolated pockets of non-draining CSF (“Non-Communicating Hydrocephalus”); however, Cerebrovascular (Blood) Dynamics and Cerebrospinal Fluid (CSF) Dynamics are inextricably linked due to the enclosed nature of the cranium**.

NIagara Falls
Cerebrovascular ICP Dynamics
frozen waterfall
CSF Dyamics

 

*Monro-Kellie Doctrine

**”Monro-Kellie 2.0, The Pathophysiology of Cerebrovascular Dynamics in Intracranial Pressure”, Dr. Agent Mark Wilson, Royal College of Medicine Branch, MI6

 

 

 

 

 

NEUROENDOCRINE THEORY FROM AN ENDOCRINOLOGIST – AN EXPERT SPEAKS

Three particular informational sources have played a key role in making sense of disparate symptoms:

  1. The Driscoll Theory by Dr. Diana Driscoll.  Although primarily focused on Ehlers-Danlos/POTS patients and the particular Intracranial Pressure Dysregulatory Disorder these patients often experience – Intracranial Hypotension – especially her observations about the carotid triangle, vagus tone, and cerebrospinal pooling/blockage due to “brain sag”.
  2. Adrenal Fatigue Syndrome by endocrinologist Dr. Michael Lam, MD and Dorine Lam, RD, MS, MPH.  A well written book describing endocrine system interactions as a result of long term, high level stress, how that system begins to become dysregulated, and the hormonal consequences thereof, as well as approaches in dealing them.
  3. Multiple Research Papers that have documented the presence of hormonal receptors in the cells that produce CSF.  In a word, many of these hormones become dysregulated in Adrenal Fatigue/Failure.  Each in its unique way contributes to increases in blood pressure, CSF production – or, as in the case of aldosterone – is responsible for both.  This means increased blood pressure & therefore increased Cerebrovascular Dynamics as well as increased CSF production.  The perfect storm for development of elevated ICP, and if not controlled, an ICPDD in patients with predisposing factors.  Some receptors are estrogen/progesterone sensitive, possibly explaining why patients are more commonly female.   Further,  looking back to Dr. Lam and Dorine Lam’s body of work, it will be interesting to compare the upswing in ICPDD diagnosis with the increase in estrogen-like compounds in everything from food supply to dental fillings.

All these fell in my lap within a two week period in December 2018 while I was hunkeringS down waiting for a shunt revision, and to my surprise, they did not lead me to what I was looking for: why I developed IIH.

Well, sort of.

They actually led me to a conclusion that I cannot emphasize enough, hence the big letters here:

“The Secondary Acquired Adult Onset form of the “disorder” known as IIH is actually a complex symptom of a dysregulated endocrine system, including “Adrenal Fatigue”, which is most commonly caused by chronic stress.  Therefore, I name CHRONIC STRESS to be the main cause of altered/elevated ICP and the onset of ICPDDs, and the ultimate reason I developed an ICPDD.”

Shuntwhisperer’s Neuroendocrine Theory of IIH, Dec 2108

But wait, there’s more:

“Successful treatment of ICPDDs must necessarily involve endocrine function AND CAPACITY* before any ICPDD can be successfully treated.  To treat only the ICPDD is treating only the symptom; without lifestyle/dietary changes and endocrine support can possibly condemn a patient to unnecessary prolongation of their ICPDD.”

Shuntwhisperer Neuroendocrine Theory of IIH Corollary #1 Jan 2019

And just when you didn’t think it could not get ANY better:

“Elevated ICPs cause deformation and damage to key portions of the brain controlling the endocrine regulation, especially the HPA Axis.  The HPA axis must be well regulated to maintain ICP equilibrium.  THEREFORE: TREATMENT OF ICPDDS WITHOUT TREATMENT OF ASSOCIATED ENDOCRINE DYSREGULATION WILL BE SUBOPTIMAL.”

Shuntwhisperer’s Neuroendocrine Theory of IIH Corollary #2 Jan 2019

In other words, endocrine dysregulation that leads to an ICPDD, left untreated, can cause the ICPDD to persist, and more corollaries are coming.

But don’t take my word for it.

Take an expert’s.  I swear, I did not rip this off, but Dr. Lam’s book led me to the same conclusion:

NeuroEndoMetabolic Component Dominance: Stages of Stress

Been a long hot summer day.  I miss Trina.  Leaving you to it.

The ShuntWhisperer

July 11, 2019

 

Stressed-Out-1024x614

 

 

 

 

THE HOLE IN MY HEAD AND HOW FIXING IT FIXED ME -HOPE FOR OTHERS?

If anyone has a shunt and it’s not working, you might want to read this.  I don’t know if applies to anyone else or not, but it’s been nothing short of a miracle for me.

 

This is an extremely condensed version of an extremely long story relating to my personal struggle with intracranial pressure disorders.  I’ve been waiting to see if this is really as good as it seems and now feel like I need to share it with everyone in the event it helps somebody else.  I originally addressed this a year ago in a post entitled “Juice Boxes and My Brain” in the original version of ShuntWhisperer because of the way juice leaks around the straws in juice boxes and pouches when they are squeezed.  I’ve now been treated with great improvement to my condition, and here is the synopsis:

I received my first shunt in March 2017.  For the first few weeks it seemed like an answer to prayers, quite literally.   However, after about 2 weeks, symptoms began to return, although a little different than before.

Turning up the adjustable shunt helped, but within 2 weeks, I was back in the same condition.  This process, including one hospitalization for extreme lethargy, repeated over the ensuing 4 months until the shunt was at its maximum setting and I was struggling.  My symptoms were:

  1. Extreme sensitivity to changes in barometric pressure/elevation.   Changes of as little as 10 millibar (mb) affected me depending on whether the change was up or down, and larger changes, such as those associated with a storm, left me bedridden.
  2. Intolerance to heat
  3. Extreme fatigue
  4. Poor sleep
  5. 3-4 hours every morning to get to the point of being able to “function”.  I lived with a coffee cup in my hand.
  6. Instead of pressure inside my head, I had a “hollow” feeling
  7. Swelling along the shunt catheter under my scalp from point where it was inserted into my skull on days when my ICP was “higher”; barely visibly noticeable, but I could feel the difference.  Least noticeable in the morning, more noticeable as the day went on, especially if I was trying to do something physical.
  8. Change in the shape of the indentation over the surgical access in my skull, in the same manner as the swelling along the shunt.
  9. Aggravation of these symptoms after eating more than a small amount of food.

Here are pictures of my shunt in “normal” and swollen condition; these were taken well past the time my skull should have healed:

“Normal” appearance of shunt

flat shunt

Swollen appearance of shunt:

Distended shunt

Capture from MRI 16 months postop showing persistent lack of healing of the bone and pathway (marked in red) for CSF leakage:

Unhealed Craniotomy

Through this all, a series of events unfolded which prevented me from having any definitive treatment, including the death of my wife Trina.  While treatment options were falling back into place, these symptoms temporarily stabilized in early 2018, then reverted to high ICP symptoms in June when summer heat came.

About that time I noticed that the swelling along the shunt catheter had nearly stopped, and that made me aware of a possible likely explanation for my symptoms.  It turns out that my profession allowed me to recognize the clues right in front of me.  Before  IIH forced me into retirement, I had been a dentist.  I was very involved in treating patients with dental implants, especially the surgical aspect.  Implants require very precise placement to be successful, but often changes or shrinkage in bone after loss of a tooth makes placement impossible without first modifying/grafting of the bone in the area to be implanted.  As such, I had developed the knowledge of how bone grows, or in my case, failed to grow to be able to recognize what might be responsible for my unstable outcome.   I realized that the hole in my skull had failed to heal to the degree necessary to prevent unwanted leakage of CSF along the slick silicone catheter and under my scalp.  This caused unwanted leakage of CSF as well as interfered with intended ICP management by my shunt.  As months went by, there was some healing, enough to plug the leak to the point where, with my shunt set to maximum, my ICP was too high, especially when summer heat set in and my ICP went up even farther.  Adjusting the shunt downward in pressure helped with the excessive ICP, but I still fought stability issues.  Finally, my neurosurgeon and I decided to try to repair the surgical hole in my skull, a relatively easy procedure.  This was done in March of 2019. 

The condition I was coping with is known as peri-tubal leakage.  Shunt catheters are slick silicone; tissue heals around them, but not to them.  It is possible for CSF to find its way between the tissue and the outside of the catheter out of the cranium and under the scalp, where it follow the shunt components until absorbed by the body.  It wreaks havock on ICP and CSF dynamics.  Information on this condition is sparse, to say the least.  I could only find one article referenced below; the pictures in the article are of pediatric patients; the leakage shown thus appears much more dramatic.  

From International Archives of Integrated Medicine: this article covers more than one potential complication of shunt placement, but the swelling of the shunt catheters under the scalp is what this Whisper is concerned with:

https://iaimjournal.com/wp-content/uploads/2015/09/iaim_2015_0209_12.pdf

This reference pertains to lumbar-periotoneal shunts:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4533463/

From the moment I remember coming out of anesthesia, I could feel a positive change.  The next six weeks were a little unstable as the surgery healed, but still much better than I had experienced since the first shunt surgery.  Now, 3 months later, I have the best stability I”ve had since the onset of my first IIH symptoms, and after some minor tweaks to the shunt setting, I feel as close to “normal” as I have in 3 years.  I still have lingering issues, but compared to the condition I was in before, I can live with them.   Furthermore, I feel a little better every day.  Previous triggers like heat, changes in barometric pressure either no longer bother me or their effects are greatly reduced, just by sealing this small opening in my skull under my scalp.

I can’t say if this affects anyone else.  It did affect me, and repairing the initial surgical access in my skull has made an enormous improvement, and I am sincerely grateful to Dr. Kenneth Liu and Penn State/Hershey Neurological Services for their efforts.  For the first time in 3+ years,  I feel like I have some quality of life, an I thank God for this answer to my prayers.  If this helps anyone, don’t thank me, thank God and your neurosurgeon.  I’m just a grateful messenger.

The Shunt Whisperer

May 28, 2019

Happy Birthday, Sweetheart

 

THE NEUROENDOCRINE THEORY – HOW I BELIEVE I DEVELOPED IIH

I’m away from my computer at the moment. Mixed feelings, that…at any rate, I wanted to start getting this idea out for discussion. I’ve been wanting to get it out for four months, but I was just too sick to drive my computer after performing the basic tasks of paying bills, laundry, opening a can of Campbell’s Kettle Cooked soup (not a plug, Campbells isn’t paying me a darn thing, but for $2.50 from Amazon, the Jambalaya and White Chicken Chili is not too bad).

I will only be posting the bullet point outline of my theory today due to limitations of typing on a phone as well as the need to present aspects of each point in greater detail in the proper order. And, while this is MY theory of how I developed “IIH”, I have witnessed it play out personally in two people I know personally (both female), as well as seen it as a theme in many other “IIH” patients in various support groups. I suspect this process may likely apply to others as well due to commonalities in physiology between human beings, but I don’t represent it as the ultimate explanation for all Adult Onset Acquired/Secondary IIH/PTC/NPH.

I put this theory together through months of research, review of my medical records, family interviews, and the following publications I urge everyone coping with this disorder to read:

1) “The Driscoll Theory” by Dr. Diana Driscoll, available on her website PrettyIll.com (thank you Renee for bringing this to my attention). While Dr. Driscoll’s focus is primarily related to complications off Ehlers-Danlos Syndrome in which altered intracranial pressure is a common symptom, I believe much of her theory applies to non-EDS patients with altered ICP as well, and will discuss this in detail in the near future.

2) “Adrenal Fatigue Syndrome” by Dr. Michael and Dorine Lam. Adrenal Fatigue Syndrome (AFS) is a condition that develops in cases of prolonged stress. This can result in a blunting of the endocrine response to stress, and Dr. Lam details what the result of this altered endocrine response can cause. I have been dealing with AFS most of my professional life, and it has been a significant obstacle in my recovery.

Even with these contributions, I still didn’t understand how stress causes increased intracranial pressure. However, shortly after reading Dr. Lam’s book, a research paper from 2013 literally fell into my lap, a veritable Rosetta Stone tying everything together.

I need to state this theory is based around my initial postulate that ICP in adult onset secondary “IIH” is governed primarily by cerebrovascular/blood dynamics. Blood is the ONLY fluid that flows into the brain/skull at a rate of 750-1000 cc/minute at rest. CSF is made from arterial blood in the brain at a mere 0.35 cc/minute. While CSF can make a significant contribution to ICP, failing to take cerebrovascular dynamics into account ignores the 800 lb gorilla in the head. I arrived at this in a rather “side-loaded” manner, but I’m not the first to make this observation:

Dr. Mark Wilson, Neurosurgeon, Royal Academy of Medicine: Monro-Kellie 2.0: The dynamic vascular and venous pathophysiological components of intracranial pressure

Thus, without further rambling, The ShuntWhisperer’s Neuroendocrine Theory of Adult Onset Acquired/Secondary Intracranial Hypertension:

IIH IS NOT A PRIMARY DISORDER. IT IS A SYMPTOM OF ENDOCRINE DYSREGULATION AS A RESULT OF PROLONGED STRESS. I don’t consider this to be the only possible cause of Acquired ICP, but I believe it is how I developed my particular disorder. Thus my contention that endocrine evaluation and stress reduction are as important to optimal treatment outcome as is reduction of pathologic ICPs.

1) Pre-existing condition(s), developmental or acquired, which predisposes a patient’s intracranial pressure physiology to be higher than “normal”. Examples include but are not limited to:

a. Underdevelopment of the Venous Sinus Network, resulting in reduced absorption of CSF

b. Reduced Intracranial Volume, including Chiari Spectrum findings with or without symptoms.

2) Past Physical Trauma, especially cervical trauma

3) Autoimmune/Inflammatory conditions with or without symptoms, especially IBS, Crohn’s Disease, gastroparesis, endometriosis, and Polycystic Ovary Disorder

4). Female Sex

5). Exposure to prolonged stress with alteration of endocrine stress response, especially “blunting” of the Recovery Phase from initial Fight/Flight Response.

and finally:

6) Precipitating Stressor. This critical event can be physical and/or emotional, and pushes a patient’s quiescently challenged physiology into an area where increased ICP and associated serious consequences develop. If, as in my case, it results in a dramatic and unexplained loss of function which threatens livelihood, relationships, and pleasure activities, this can initiate a vicious cycle of increasing intensity until the patient has very limited or no ability to function.

The Good News: based on observation of the early onset of IIH in several patients, I believe that ICP is reduced into a normal zone while the patient’s body still has the ability to heal the damage caused, remission is possible when accompanied by lifestyle changes to reduce stress, dietary changes, and monitoring. Reduction of ICP at this time may be able to accomplished with very small doses of Diamox/acetozolamide.

So there it is, for what it’s worth. Over the next few weeks I will fill out pertinent details, with research references. Again, this is my theory based on my experience; I have no idea how broadly it applies to any other patient, but I’m beginning to see similar notions from medicine.

As always, prayers for comfort and food days to all & May God Bless each of us, our families, and our doctors.

April 30, 2019

The Shunt Whisperer

SHUNTWHISPERER 2.0 – NEW PERSPECTIVES, NEW THEORIES, BETTER OUTCOMES AND QUALITY OF LIFE

“…My last post was in late 2018 regarding an epiphany I had been given regarding a theory about how a person develops acquired adult IIH. Of course, right at that point, the creaking, weak, bottom fell out from under me.

Again….”

Note:  I need to acknowledge something to a person who reached out to me for help.  This person believed they were developing an infection of their shunt and were desperate.  Due to my own recent challenges, I didn’t open that email until a week later, and then due to some strange glitch, lost it entirely.  To that person, I am deeply sorry, and I pray you were able to avail yourself of the ER in time.  FWIW, I just went through the same problem 7 weeks post-revision.  I post my email contact, ShuntWhisperer@ShuntWhisperer.com to help answer questions if possible, but I am not a neurologist or neurosurgeon, and if anyone should find themselves in and emergency situation (infection of the shunt tract qualifies), get to your physician or ER first, then email me if you like.  FWIW, I am making it a point to check my email every morning at the very least as long as I am able.

 

Greetings to all. 

It’s been a minute, to be sure…more like 4 months.

My last post was in late 2018 regarding an epiphany I had been given regarding a theory about how a person develops acquired adult IIH.  Of course, right at that point, the creaking, weak, bottom fell out from under me.

Again. 

I had to devote what little functional capacity I had to managing this new challenge; making new posts here was just not possible.  February was a very, very, very (etc.) difficult month.  Most days I felt like I a lone person in a dark void above a bottomless abyss, clinging by my fingernails to my spiritual, almost tangible touchstone, Jesus Christ.  I can say with complete certainty He is the only reason I am still here to right this story.

The Lord works in His own way(s).  In my case, Dr. Kenneth Liu of Penn State Neurological Services, the neurosurgeon who saved my life by placing my first VP Shunt two years ago, revised my shunt and repaired the inexplicably persistent hole/CSF leak associated with the craniotomy (surgically created hole in my head).  I referenced this problem in the post “Juice Boxes and My Brain…Who Knew?). I can now say with a weird sense of satisfaction that I now have a metal plate in my head.  A small one, but nonetheless, a metal plate.

Cool.

This surgery resulted in an immediate, marked improvement, but still with instability, though not nearly as severe.  There was still a small but noticeable  CSF leak.  At 5 weeks that last leak suddenly stopped, and it was as if my brain had suddenly been switched back “ON”.  Most notable was that extreme sensitivity to certain triggers, especially barometric pressure, was either drastically reduced or eliminated altogether.   Before the revision surgery, I could not stay at my new retreat in the mountains at a modest 2200’ elevation if the barometer dropped below 940 mb.  I would become bedridden with fatigue, pain, and ‘brain fog’.  I would be forced to leave the mountain for lower elevations, and I began to be able to predict at which turn in the road I would start to feel improvement.  I would stay at a lower altitude for a week, and when I felt better, I returned, only to have the scenario play out over again within the next 7-10 days.  Was this real, or was it some perverse trick of my psyche?  I decided to find out, and with a prescription from Dr. Liu, I bought a home hyperbaric chamber.  Expensive, but it was the only way I knew to answer the question about the effect of barometric pressure on my personal form of this disorder.

I’ll go into more detail about the chamber later; for now I’ll just say I ran a series of controlled experiments.  The results were undeniable: climbing in the hyperbaric chamber and simply increasing the pressure inside to 30mb above local pressure reduced or eliminated by pain and feelings of fatigue.  However, no matter how long I stayed in the chamber, once I exited, those symptoms returned in 1-6 hours depending on local conditions, so there was no doubt that this small change in barometric pressure was enough to drastically affect my well being.

I also noticed something else: when I got out of the chamber, I could feel my shunt flowing.  If you have a shunt, you know what I mean.  More importantly, I noticed that swelling developed along the shunt components under my scalp starting at the craniotomy and eventually proceeding back to behind my ear.   I interpreted this as a CSF leak.  The catheter that connects to the shunt valve is a surgical silicone; human tissue does not adhere to this material.  I also discovered these catheters are further treated make them even more resistant to the adhesion of cells in order to prevent stray bits of protein and brain tissue from adhering to the inside of the catheter and eventually blocking it; this treatment is intended to prolong the life of the shunt.  In my case, bone had failed to fill back in the craniotomy, leaving a path for CSF to leak between the outside of the catheter and the dura and along the catheter and shunt under my scalp.  This resulted in overdrainage of CSF as it was drained not only from inside my brain as intended, but from outside the brain as well.  This caused me to experience intracranial hypotension, and was a truly miserable test of my personal belief that a more appropriate term for this disorder is Intracranial Pressure Dsyregulatory Disorder (ICPDD). 

I took this information to Dr. Liu and ultimately the decision was made to revise the shunt and repair the craniotomy.  Now that this unwanted leak has been stopped I have experienced increasingly stable improvement of my disorder, including greater functional capacity and dramatically reduced ‘fibro’ pain.  I still have challenges from the effects of almost 2 years of wild swings in my ICP, including physical deconditioning.  Spring weather patterns here have been brutal, with at least 4 “bomb-grade” storms (defined as a weather system with at least a 24 mb drop in barometric pressure in 24 hours) in the last month.  Prior to the March surgery, these systems invariably laid me up for at least three days; now, their effects on my disorder are greatly diminished, and seem to be continuing to diminish with each passing day.  Only one recent freak set of back-to-back storms really hit me hard, but in that case there was also a potentially serious late postop complication that I was fortunate to recognize and address before it got out of control.

All this preamble brings us to now.  ShuntWhisperer started as merely a “this is my story, maybe it will help you” type of blog.  Over the course of two years, I’ve learned more as I’ve continued research and experienced new challenges that while very difficult, contributed to a better understanding of my disorder.  The structure of the original site was never intended to present this material of this depth in a coherent and orderly manner.  I never expected it to be more than a few pages, but it has blossomed well beyond that.  Thus I will be  restructuring the site “on the run” as ShuntWhisperer 2.0.  It is intended to be concise, presented in lay language to the degree possible, and accompanied by references to existing research, with a reference section for physicians.  Please don’t expect a visually dazzling site; I simply don’t have the time to post anything but pertinent information.   Also, the original ShuntWhisperer site and its contents will still be available, accessible from the new landing page.

SW 2.0 is still intended to be based on my personal experiences and research.  I can’t claim anything I post applies to any other person with a disorder of altered intracranial pressure, although there are certain immutable laws of human physiology that lead me to suspect that is indeed the case; I just can’t make that claim.  I’m not sponsored, I don’t get paid for this, and don’t care to receive any credit for any good that comes of what I post.  I am doing this in Service to God in an attempt to help others, as well as in memory of my wife Trina.  My contact email is Shuntwhisperer@shuntwhisperer.com for anyone who has a question, feedback, or suggestion. 

As always, prayers to all for comfort, support, and a better quality of life.

 

Wes

The ShuntWhisperer

April 26, 2019

 

Today’s storm and rain has passed; it’s a gorgeous spring day on the mountain, and I’m going to take a break to enjoy it, wishing Trina was with me.

“But ask the animals, and they will teach you, or the birds in the sky, and they will tell you; or speak to the earth, and it will teach you, or let the fish in the sea inform you.  Which of all these does not know that the handoff the Lord has done this?” 

           Job 12: 7-9

 

#CROWDHEALING VALIDATED: IIH, EDS, & POTS: THE DRISCOLL THEORY (AND NOW, ADRENAL FATIGUE: TAKING IT ON THE LAM)

Starting this weblog over a year ago was primarily borne out of a desire to help with a disorder that even the doctors I consulted had little grasp of, much less the patients.  My theory was that by making my experience available, others might benefit.  Along the way I started noticing certain correlations in my disorder.  Perhaps this might cascade and multiply, bringing better understanding to this potentially crippling class of disorders more quickly than the glacial pace of research and publications – “Evidence Based” science, which is still an important tool in Medicine.  Thus the notion of “CrowdHealing” was borne.

The last 18+ months have been brutal.  Shunt treatment was maddeningly unstable; I now know it was because there was a CSF leak around the proximal catheter for over 9 months.  After healing stemmed the leak, I went rapidly from unstable ICP where I vacillated between too much and too little pressure, to a short period of relative stability, then to a brutal return of symptoms of unbearably high ICP where I vacillated between misery and agony.  After finally getting an adjustment to my shunt, the pressure was reduced, but my brain felt like it had been used to play soccer.  It was my sincere hope that a period of R&R would restore balance, this disorder would stop ruling my life, I could possibly return to practice, properly mourn Trina…

It was not to me. 

I now find myself suddenly extremely sensitive to barometric pressure.  I have always been sensitive to the barometer, but this new condition mimics my post-shunt condition: a few days (at best) of stability at a given altitude/pressure, followed by a gradually reduced ICP.  Worse, it seemed that I could not tolerate the mere 2100 feet altitude of my new home for more than 2 days before my head began to feel empty; after a week I was all but incapacitated by a feeling I associate with excessively low ICP.  Traveling off the mountain to lower altitudes always rapidly alleviated my symptoms of fatigue, weakness, and pain.  A change of a mere 1000 feet was enough; I could almost tell at which turn in the road I was going to start to feel better.

This seemed insane.  After all I’d been through, now I couldn’t rest and grieve in a place that was paradise to me.  Was it real or psychological?  I decided to put it to the test by acquiring a hyperbaric chamber (note: these are not toys.  I don’t recommend anyone else do this at this point.  A doctor’s clearance and order is required to purchase one, and they are expensive, like $5K+ for a basic model (thank you, PayPal Credit).  If you’re not careful, there are a number of ways you can cause harm to yourself.

All that said, within a week of getting the chamber, I had my answer:  it was, without a doubt, the barometric pressure at the altitude of my new home in the mountains that was the source of my New Misery, apparent intracranial hypotension (Intracranial Pressure Dysregulation Disorders are not just high ICP).  A mere 20mb increase in pressure began to alleviate my symptoms; I could feel my spine and head “pressurize”. 

WTF. 

Consultation with Dr. Liu ( I know he winces seeing his name here) led to the possibility of one or more CSF leaks.  At the time I write this, I’m waiting on a call from a CSF Clinic for an appointment.  Yes, I’m living at my mother’s house, 1100 feet lower in altitude, at the age of 59.  It’s actually one of the better things to happen to me in the last 18 months.

Still, it seemed insane that I went from feeling as if my head was going to explode and a return of my pre-shunt symptoms in June/July to not having enough ICP after a mere 50mm reduction in my shunt valve pressure.  It made no sense to me based on what I’d learned to this point.  These numbers are small, but here I was, isolated from  my new home by a tiny change in altitude and pressure that even my damaged physiology should be able to account for…

So I thought.

Some months back, I was contacted by a ShuntWhisperer reader who had an ICPDD attributable to Ehler-Danlos Syndrome, a disorder characterized by loose connective tissues believed to have a genetic component.  EDS patients have a high incidence of ICPDDs, both Intracranial Hyper-and Hypo-tension  She told me about Dr. Diana Driscoll, an optometrist who had EDS as well as a family of EDS?ICPDD sufferers.  Dr. Driscoll relates suffering 10 years of disability due to her condition that left her physicians confounded.  Unwilling to sit on the sidelines, more than 5 years before the idea of #CrowdHealing entered my mind, Dr. Driscoll all but invented the concept (ShuntWhisperer Theorom #242: If I can think of it, it’s already old news).  Dr. Driscoll ran with it, and is now running a clinic patients who suffer from a related disorder, POTS (Postural Orthostatic Tachycardia Syndrome).  I briefly browsed Dr. Driscoll’s website, PrettyIll.com, was impressed, ran it through my Priority List (Spoon Pile), and filed it.  I just got around to that spoon, reading her publication “The Driscoll Theory” after my appointment with Dr. Liu (aka The Man). 

My jaw still hurts where it hit the ground.  Let me be very clear: if you are suffering from one of the alphabet soups of ICPDDs (PTC/IIH/BPH/NPH/PB&J), The Driscoll Theory is an absolute MUST READ.  Forget if you have been diagnosed with Ehlers-Danlos or not.  Buy a copy for your family, your doctor(s), anyone else you can think of.  The $9.95 goes directly to research:  The Driscoll Theory addresses sound physiologic conditions that can explain the onset of altered intracranial pressure, in my current opinion, independent of any connective tissue disorder such as Ehlers-Danlos.  It goes back to neuroendocrine stress I originally referenced in the ShuntWhisperer post “You’re Fat And That’s Why You Have IIH – Lose Weight and You’ll Get Better“.

I have a “Mind Map” of my disorder; there are outlying symptoms that I had yet to connect to the main map.  I also had one for Trina that was essentially a jumble.  Two other close ICPDD patients as well in varying degrees of connected dots.  Two hours after opening The Driscoll Theory, I’ve pretty well completed those mind maps, and believe I may be seeing the very early stages of altered ICP in another person in my circle for reasons that are clearly outlined in Dr. Driscoll’s work.  In her Theory, Dr. Driscoll she believes (backed up by already accepted medical and physiologic tenets) is responsible for the ICPDDs seen in EDS patients.  (Note: 12/26/2018 – small test doses of acetazolamide yielded positive impacts on symptoms of this patient – more to follow).

I see way more than that.  I see the potential cause of secondary(?) ICPDDs in general.  Like the Missing Link, The Rosetta Stone, the CryptoSkeletonKey of dyregulation of intracranial pressure.  I’m early into this, but I believe Dr. Driscoll has broken the #CrowdHealing barrier of the cause of secondary alterations of ICP alterations. 

As Dr. Driscoll’s work is copyrighted, I want/need to contact her before I start expounding on what I’m seeing outside of her site, but suddenly I’m very hopeful, as well as very concerned.

 It’s a new game now, folks.  Enough of my meanderings and mumblings, there is something to sink our collective teeth into here.

12/26/2018: Note:  Another giant piece of this puzzle is now available: the effects of long-term stress (“Adrenal Fatigue Syndrome”) on the human body, especially the female physiology.  I refer you to: DrLam.com

The ShuntWhisperer

Trina, I finally have answers….I’ll look out for him/them.

Welcome To The Shunt Whisperer 2.0

Welcome to The Shunt Whisperer.  I’m a 57 year old professional forced into retirement and disability as the result of a sports injury over 10 years ago.   I was treated with a VP shunt in May 2017 as treatment for an Intracranial Pressure Spectrum Disorder (ICPSD).  In my case, it the initial diagnosis was Idiopathic Intracranial Hypertension, the result of a neck injury.  At least that’s when the symptoms that seem to be relieved by the shunt appeared.  This purpose of this site is to tell the story of what having a shunt has been like, insights I’ve had as a shunt patient with medical training, and where I think shunt treatment needs to go.  I want to help others understand their condition better and hopefully live a better quality of life.  Having a hole in your head and a tube in your brain isn’t much help if you can’t get out of bed or engage in activities that bring you satisfaction. 

Nothing herein is intended to be critical.  ICPSDs have only recently been recognized as real, explaining a handful of conditions that have confounded medicine for over 20 years.  The reality is that right now, there are only a handful of specialists, chiefly neurosurgeons and neurologists, at a few centers around the nation, that are willing to step in and treat this condition.

The reality of ICPSD treatment is this:  it is in the early stages.  Methods and devices are evolving to meet the need of an adult population with an ICPSD.  Basically, diagnosis of an ICPSD means too much blood and/or cerebrospinal fluid is being retained in our central nervous system (brain and spinal cord).  Excess fluid leads to excess pressure which can damage the brain directly including the optic nerves/auditory nerves, as well as stress parts of the brain that control our bodies’ functions including blood pressure, body temperature, weight, sleep cycles, and others, and is linked to conditions such as fibromyalgia and dementias.

My experience thus far has been the equivalent of Alice falling down the Rabbit Hole.  I’m told I fall in what is believed to be 20% of patients who develop secondary symptoms after shunting.  The experience has not been without positive results, however, including a significant drop in a severe and debilitating chronic “fibromyalgia” pain, as well as an improvement in my physical function.  Understand that I have been dealing with symptoms that were relieved with the shunt in March 2017 since a neck injury in mid 2007.   There is no doubt the shunt helped me, no doubt it was the best option at the time.  It hasn’t been perfect, but after six months of living with it, I believe I know a few things that can help.

It’s my hope that telling my story helps somebody else be more informed and less surprised/confused by their ICPSD and it’s treatment.  Don’t use this information to make major health decisions without consultation with your physician.  It’s just here to give a little more understanding into this condition and treatment from someone who has and is currently undergoing it.  I have a fear that if I don’t put this information out there, it might not get to somebody who needs it.  It takes a lot of my available energy to do this; as such, it may take a while between additions and updates.

Prayers and Blessings to everyone,

The Shunt Whisperer

October 6, 2017

How Intracranial Pressure Becomes Elevated: Part 2, Short and Sweet

Intracranial Hypertension is the elevation of pressure  of fluids and tissue inside the fixed volume of the rigid intact skull.   This elevation of pressure has two basic mechanisms*:

  • Cerebrospinal Fluid Dynamic Imbalance: A net accumulation of of Cerebrospinal Fluid (CSF).
  • Cerebrovascular Dynamic Imbalance: A net accumulation of blood in the brain caused when veins are not capable of draining the volume of blood pumped into the brain by the heart (Monro-Kellie 2.0, Dr. Mark Wilson, Royal College of London, 2016)

*soft tissue tumors can also occupy space inside the skull and potentially raise ICP but are considered a separate causative mechanism from those that are considered in ICPDDs

The cause of these imbalances can be either genetic/developmental (primary) or related to trauma (secondary).  They are closely interlinked and may both be present to a certain degree.

One example of CSF Imbalance would be non-communicating hydrocephalus.  CSF is produced from arterial blood in small hollow areas of the brain called ventricles.  Ventricles are normally interconnected with one another and the space around the brain.   CSF circulates through these areas passively due to the pulsation of blood vessels and also likely movement of the body.  If one or more of these ventricles does not communicate with the rest of the system, the CSF it produces accumulates and displaces the brain outward.

Another exmaple of CSF Imbalance illustrates the interrelationship between CSF and Blood dynamics:  obstructed veins may not absorb enough CSF out of the skull to prevent a net accumulation of CSF, as well as leading to this example of:

Cerebrovascular Dynamic Imbalance: would be Chronic Cerebrovascular Venous Insufficiency, or CCVVI.  In simple terms, damage or constriction (stenosis) of one or more of the veins that drains blood from the brain compromises the ability of blood to leave the brain.  At a certain critical level of blood flow and pressure, blood begins to accumulate in the brain as it is pumped through arteries at a greater volume than it can drain.  This accumulation of blood causes the thin-walled veins to swell, which in turn pushes on brain tissue.  Brain tissue may become displaced as a result, being pushed into areas occupied by CSF.  Since an intact skull is rigid and does not expand, the pressure of the CSF becomes pressurized (Newtons’s Third Law)  while simultaneously trapping brain tissue between a vise of swelling veins.    As focal areas of brain tissue that control specific physiologic functions become stressed, their functions become altered.  This pressure on brain tissue is likely the cause of symptoms associated with IIH.

THE MECHANISMS OF ICPDD: HOW INTRACRANIAL PRESSURES BECOME ELEVATED: PART ONE

 

 

Everybody knows the old adage about how to eat an elephant.   ICPDDs and their nuances certainly qualify, and the goal here is to present information in easily digestible bits.  This is the first bite.

While the reason/reasons (“etiology” it doctor-speak) a person develops IIH/PTC/etc. remain unknown and controversial, the physiology of how the pressure develops is actually quite straightforward:  ICPDDs reflect an increase in the pressure of fluid in and around the brain.  Thus, they are a result of a disruption in the dynamics of the fluids in and around the brain.  While CSF is most commonly discussed and treated, there is another fluid that actually rules everything, including CSF:

Blood.

FLUID DYNAMICS

Blood is the 800 lb Gorilla of the brain.  It is pumped into the brain primarily through the

Coronal view of Brain and Carotid arteries
The Carotid Arteries and their branches supply enormous volumes of blood to a nutrient-hungry brain. Note how close the brain is to the heart, which is just out of the bottom of the frame. Image courtesy of The Mayfield Brain Foundation.

carotid arteries at a rate of 750 to 1000 cc/minute when we are at rest; it courses through an estimated 100,000 miles of blood vessels delivering nutrients and oxygen to brain tissue.  Depleted blood is drained via the venous sinuses, a network of veins around the brain, and eventually through the jugular veins back to the heart.

Blood enters the brain at an average pressure (“Mean Arterial Pressure”, or MAP) of 90mm Hg.  It drains from the veins at a pressure of 15-20 mm Hg. Because the same amount of blood that flows into the brain has to flow out, and because venous pressure is lower than arterial pressure, the blood flow in veins must be higher to compensate (fluid dynamics, Bernoulli, a couple other Italian guys in there).  Suffice it to say that veins have to be able to carry away ALL blood that is pumped into the brain.  In addition to that important necessity, there are TWO factors of blood that must be considered in ICPDD: pressure (as expressed by MAP), and flow.  For the sake

venous sinuses
A very basic illustration of the venous sinuses responsible for carrying blood away from the brain and back to the heart.

of simplicity we will use heart rate as an indicator of blood flow.

 

 

 

 

 

 

 

 

 

 

CSF is a plasma like fluid that is made from blood in an interconnected network of small hollow areas in the brain known as ventricles.   It is produced at a very low

Ventricles of the brain
Blue areas represent CSF filled spaces. The approximate volume of the ventricles is 30 cc; total CSF in and around the brain is ~150cc. Image courtesy of the Mayfield Brain Foundation

rate of ~0.35 cc/minute from arterial blood.  Its rate of production is dependent on the am

ount of blood flowing into the brain.  CSF circulates through the ventricles and around the brain; this circulation is slow, with pulsations from blood vessels and body movement being the primary motivators.  It is primarily absorbed back into the blood circulation in the venous sinuses.

CSF is something of a Mystery Fluid.  Aside from cushioning and supporting the brain, it is thought to play a role in delivering nutrients and cleansing dead cells from the outer surface of the brain.  Deficiencies in CSF are associated with accumulations of these dead cells, known as plaques, which are themselves associated with dementias such as Alzheimers and Lewy Body.  Anyone with an ICPDD can tell you that “overdrainage”, ie, not enough ICP and/or CSF makes them feel weak and lethargic.   Again, suffice it to say that CSF is Very Important; otherwise, it would not be in our heads.

SUMMARY, PART ONE:  THE TWO FLUID POSTULATE

The dynamics of blood and CSF lay the groundwork for understanding ICPDDs.  ICP is a result of the interaction of these fluids inside the watertight, airtight, non-expandable skull.  These facts lead to what I call the Two Fluid Postulate:

“There are only two fluids inside the skull: blood and cerebrospinal fluid (CSF). Both are present in approximately equal volumes, 150cc. Only one flows in and out of the brain:  blood.  CSF is made from blood that enters the brain and absorbed back into the veins that drain blood away from the brain.  Intracranial pressure is the sum of the forces exerted within the skull by these two fluids.  Changes in the balance of CSF production/absorption and/or blood flow into and out of the brain will necessarily affect ICP.  Most critically, because the brain is encased in a rigid, non-expanding skull, ANY INCREASE IN ICP TRANSLATES INTO INCREASED PRESSURE DIRECTLY ON THE BRAIN.”

This is just a restatement of what is known as the Monro-Kellie Hypothesis from the 1890s by two Scottish physicians to explain what goes on inside the skull.

THE TAKE-AWAY:

CSF, while the most often discussed fluid in ICPDDs, is not the only fluid in the brain.  Blood, in fact, rules everything inside the skull, including CSF.  Because the volume inside the skull is fixed, and because there practically zero extra space in the skull, any net accumulation of CSF OR Blood will cause increased ICPs, and those increased ICPs exert direct pressure on the brain itself.

In Part 2, we will look at how the dynamics of blood and CSF become disrupted.