Chiari Bridges

Tag: Empty Sella

  • The Important Questions to Ask Your Neurosurgeon [Revised]

    The Important Questions to Ask Your Neurosurgeon [Revised]

    Most Chiarians go to see a surgeon with an expectation of them being knowledgeable in their field. However, while they might be a neurosurgeon, their knowledge of Chiari and its comorbid/pathological conditions might not rank high in their practice. Make the most of your initial appointment by interviewing them and what they really know about Chiari Malformations. Be cautious of inflated success rates. Chiari decompression in general offers a just over a 50% success rate (which means it has a nearly 50% failure rate). Surgeons that claim a 100% (or near 100% success rate) are usually not basing their success on how their patients feel afterward, it is based on if they were successful with the aspects of the surgery:
             Removal of the occipital bone ✓
              Opening the dura and adding the patch/graft ✓
              Laminectomy ✓
              Cauterization/resection of cerebellar tonsils ✓

    WE DESERVE BETTER THAN THAT!

    HERE IS A LIST OF CHIARI QUESTIONS WE RECOMMEND ASKING AT YOUR FIRST NEUROSURGERY APPOINTMENT:

    General Questions:

    • How do you define a Chiari Malformation?
    • What do you believe causes a Chiari malformation?
      • Are all Chiari malformations from a small posterior fossa?
      • Do I have a small posterior fossa? If yes, how big is it? If size is unknown, was my posterior fossa measured? If not, why not? How did you come to the conclusion that I have a small posterior fossa?
      • How common do you believe Acquired Chiari malformations to be?
    • Do you always recommend decompression surgery for all of your patients with herniated cerebellar tonsils? Why/why not?
    • In an average month, how many Chiari decompressions do you perform? How many tethered cord releases? How many craniocervical fusions? What percentage of your practice is spent treating patients with these connective tissue related conditions?
    • Looking at my brain scan, is any part of my “brainstem” herniated (below the posterior fossa)? If so, does that make me a Chiari 1.5?

    Intracranial Hypotension (low pressure) Questions:
    *Article to help you understand CSF Leaks & Intracranial Hypotension prior to your appointment.
    If you have SYMPTOMS OF LOW INTRACRANIAL PRESSURE and/or suspect a cerebrospinal fluid leak, we recommend asking the following questions:

    • S.E.E.P.S.
      • Looking at my brain scan, do you see any Subdural fluid collections?
      • Looking at my brain scan, do you see an Enhancement of pachymeninges?
      • Looking at my brain scan, do you see an Engorgement of my venous structures? Should we do an MRV to make sure?
      • Looking at my brain scan, does my Pituitary appear to be enlarged?
      • Looking at my brain scan, does my brain appear to be Sagging?
    • Looking at my corpus callosum:
      • Does there appear to be a depression?
      • Is there an inferior pointing of the splenium?

    If he/she answers affirmatively to any of the above S.E.E.P.S. questions, ask: 

    • What should be done to find/repair a potential leak?
    • Are you aware that it is common for CSF Leaks to not show up on MRI?
    • Are you willing to do a CT Myelogram and/or a digital subtraction myelogram, if I develop symptoms of a leak and none can be found on MRI?
    • Are you aware that it can often take multiple epidural blood patches to try and seal a leak, and sometimes when a blood patch fails to work, a surgical dural repair might be necessary?

    Intracranial Hypertension (high pressure) Questions:
    *Article to help you understand Intracranial Hypertension prior to your appointment.
    If you have SYMPTOMS OF HIGH INTRACRANIAL PRESSURE, we recommend asking the following questions:

    • Looking at my brain scan, do I have cerebrospinal fluid in my sella turcica (Empty Sella Syndrome)?
    • Looking at my brain scan, do you see any evidence of my optic nerves are swollen (papilledema)?
      • If so, should I be referred to a neuro-ophthalmologist?
    • Looking at my brain scan, do my lateral ventricles appear small or flattened?
      • If so, do I need to have my pressures checked?
        • If yes, are you aware of the risks of developing a CSF Leak from a lumbar puncture?
      • What are the symptoms of a CSF Leak, should one develop?
        • What is your plan of action if I should develop these leak symptoms?
        • Are you aware that it is common for CSF Leaks to not show up on MRI?
        • Are you willing to do a CT Myelogram if I develop symptoms of a leak, and none can be found on MRI?
      • Should a leak be found, are you aware that it can often take multiple epidural blood patches to try and seal a leak?

    Tethered Cord Questions: 
    *Article to help you understand Tethered Cord: Sorry, Coming Soon.
    If you have SYMPTOMS OF TETHERED CORD, we recommend asking the following questions:

    • Looking at my brain/cervical scan, does my brainstem appear to be elongated?
    • Looking at my cervical scan, does my spinal cord appear to be stretched?
    • Looking at my lumbar scan, does my conus reach my mid/low L2?
    • Looking at my thoracic and lumbar scan, does my spinal cord appear to be pulling to the back, or one particular side?
      • If so, should we do a prone MRI to see if it has actually adhered to that side?
    • Looking at my lumbar scan, do I appear to have fatty tissue inside the epidermis?
      • If the answer to any of these questions is affirmative, do you suspect that I have a tethered spinal cord?
      • If so, should we plan for a Tethered Cord Release before or soon after decompression surgery, so the likelihood of a failed decompression is reduced?
      • If I have urological issues, can I get a referral for urodynamic testing to rule out any other potential causes of my urological issues?

    Craniocervical Instability (CCI) & Atlantoaxial Instability (AAI):
    *Article to help you understand CCI & AAI prior to your appointment.
    If you have SYMPTOMS OF CRANIOCERVICAL INSTABILITY or SYMPTOMS OF ATLANTOAXIAL INSTABILITY, we recommend asking the following questions:

    • Looking at my brain/cervical scans, what are the measurements of my clivoaxial angle and Grabb-Oakes?
    • Do these measurements meet the diagnostic criteria for Craniocervical Instability?
    • Looking at my flexion and extension imaging, how many millimeters of translation are there between flexion and extension?
    • Does Chamberlain’s Line cross my odontoid? If so, does it cross at a level that would indicate Basilar Invagination?
    • Looking at my rotational imaging, what is the percentage of uncovering of the right and left articular facets on rotation?
    • Do the percentages from my rotational imaging meet the diagnosis criteria for Atlantoaxial Instability?

    IF A DIAGNOSIS CRITERIA IS MET IN ANY OF THE ABOVE, WE STRONGLY RECOMMEND THAT YOU WAIT ON DECOMPRESSION AND PURSUE THE TREATMENT OF SAID CONDITION(S) AND THAT OF EHLERS-DANLOS SYNDROME, AS EACH OF THESE CONDITIONS CAN BE PATHOLOGICAL TO AN ACQUIRED CHIARI AND EACH IS A STRONG INDICATOR THAT A CONNECTIVE TISSUE PROBLEM EXISTS. 

    *The questions in this article will periodically change as we are able to expand our recommended questions.

    *Original version released September 2018, revised 2023.

  • Brain Under Pressure – A Guide to Understanding Intracranial Hypertension [Updated]

    Brain Under Pressure – A Guide to Understanding Intracranial Hypertension [Updated]

    INTRACRANIAL HYPERTENSION (IH) MEANS HIGH PRESSURE INSIDE THE SKULL.

    Intracranial Pressure (ICP) is measured in millimeters of mercury (mmHg). Most scholars agree that on average, “normal pressure” should be between 5-15 mmHg, mild to moderate intracranial hypertension between 20-30 mmHg (which “requires treatment in most circumstances”), and an ICP of > 40 mmHg indicates “severe and possibly life-threatening intracranial hypertension.” [1] When high intracranial pressure is left untreated, it creates a “pushing effect” towards the only natural escape at the base of the skull (the foramen magnum), and the cerebellar tonsils in the pathway are pushed through the foramen magnum. [2]

    Understanding the Monro-Kellie Doctrine (pressure-volume relationship)
    The association between IH/IIH and Chiari Malformation appears to be a malicious intricate pathological circle. The cranium (skull) consists of brain matter, cerebrospinal fluid, and both venous and arterial blood. A hypothesis, referred to as the Monro-Kellie Hypothesis (now better known as the Monro-Kellie Doctrine), states, “The sum of volumes of the brain, CSF, and intracranial blood is constant. An increase in one should cause a decrease in one or both of the remaining two.” Therefore, if an abundance of cerebrospinal fluid (IIH or hydrocephalus), both cranial blood volume and brain matter should be forced to deplete. This depletion is usually directed in the path of least resistance – through the foramen magnum and into the spinal canal. When the brain matter closest to the bottom of the skull (cerebellar tonsils) is pushed through the foramen magnum and into the spinal canal (an Acquired Chiari Malformation), the tonsils act like a cork and blocks the flow of cerebrospinal fluid (regardless of the size of the tonsillar descent), which in turn, continues to raise intracranial pressure.[3]

    More Symptoms of Intracranial Hypertension

    Venous Hypertension
    When an etiological cofactor exists (such as a space-occupying mass), it is considered Secondary Intracranial Hypertension (SIH); when no other cause was identified, it is known as Idiopathic Intracranial Hypertension (IIH) formerly known as Pseudotumor Cerebri. However, recent studies on the connection between Intracranial Hypertension and Venous Hypertension might put an end to the “idiopathic” theory.

    Oxygen-rich blood travels from the heart to the rest of the body through the arterial system, then the oxygen-depleted blood returns to the heart through the venous system. We have a host of small veins in our head and they dump into a series of large veins, called sinuses. Dural Venous Sinus Stenosis occurs when there is a narrowing of one or more of the venous sinuses (most commonly seen in the transverse sinuses or transverse/sigmoid sinus junction), which in turn compromises cerebral venous outflow through the jugular vein (stenosis/compression of the jugular vein can also result in elevated intracranial pressure [4]). Transverse Sinus Stenosis (TSS) is most common in Idiopathic Intracranial Hypertension (IIH). Depending on the study that you are reading, it is proving to be present in 90-100% of IIH patients [5]. While its connection might sound obscure if you look at it from a Monro-Kellie perspective – The blood going into the head, cannot get out at the same speed (because of the narrowed sinus). When this inflow of blood remains constant and the outflow is hindered, the transverse sinus on that side (we have two transverse sinuses, one on each side) enlarges, forcing the CSF and brain matter to reduce to maintain the volume equilibrium. This reciprocation can happen when any of the sinuses or jugular narrow (stenosis). While scholars continue to debate whether TSS is a cause or consequence of IIH, surgeons continue to decompress us without checking our pressures or decompress (the most invasive treatment) in hopes that it will lower our pressures, and patients are left with untreated high pressure still causing a “pushing down effect” and an enlarged foramen magnum for our brains to be pushed down. [2] The sagging brain once again obstructs the flow of cerebrospinal fluid by plugging the foramen magnum, and that in turn raises the intracranial pressure even more. Or, the untreated high pressure blows through the duraplasty and causes a post-operative leak, known as a pseudomeningocele.

    Reducing the Risks of Post-Op IH/IIH Complications
    Brain MRIs often show indicators of Intracranial Hypertension (IH/IIH), therefore, we recommend that all Chiari patients have full brain MRIs and not just cervical MRIs.

    • When the pressure builds inside of the dura mater the pressure pushes the dura and fluid inside of the crevice that holds the pituitary gland (the sella turcica or pituitary fossa). When the amount of fluid is equal to or greater than 50% and the pituitary gland size is 2mm, the condition is known as Empty Sella Syndrome. (Doctors now recognize that < 50% (where the pituitary gland size is 3-7mm) can also cause symptoms and they now refer to that as a partially empty sella.) [8]

    • Slit like or flattened lateral ventricles from the increased pressure, however, when the Foramen of Monro (the aqueduct that connects the lateral ventricle to the third ventricle) is stenosed, the fluid will back-up and the lateral ventricle will not appear flattened. [7]

    • Enlarged/swollen optical nerves (papilledema). [8]

    • Low lying or herniated tonsils (often diagnosed as a Chiari Malformation). [2]

    What We Recommend BEFORE DECOMPRESSION is considered:
    If you have symptoms of IH/IIH accompanied by any of the MRI indicators mentioned above, it is both reasonable and prudent to ask your neurosurgeon to investigate further BEFORE DECOMPRESSION.

    • See a neuro-ophthalmologist to check for signs of papilledema, including Optical Coherence Tomography and Ultrasonographic B-scanning. [8]
    • Magnetic Resonance Venography (MRV, preferably with the ATECO technique) to check for venous stenosis of any of the cranial sinuses and/or jugular vein. Stenosis is not exclusive to the transverse sinus and it can happen in multiple sinuses simultaneously.
    • If overweight, consider trying to lose weight. Studies show that a weight loss of 5-10% of one’s overall body weight, when accompanied by a low-salt diet, can offer some to IH/IIH symptoms.[9]
    • Consider trying Diamox (Acetazolamide) and/or Topamax (Topiramate) to see if that improves the pressure headaches.
    • Request a lumbar puncture (spinal tap) to test your opening pressures. We recommend that it’s guided with fluoroscopy with a small gauge needle (and not the standard 22 gauge) that they allow to drip (as opposed to syringe pull) and ensure that someone is available to perform an epidural blood patch if necessary. Time should be allotted afterward to lay flat for several hours immediately following the procedure and for several days once returning home. The potential for CSF leaks is high for the EDS/Chiari patient. A doctor that marginalizes the risks ahead of time, will generally marginalize your symptoms when you are actively leaking.
    • ICP Bolt Monitoring can record the differences experienced in pressure over time, and how different positions affect ICP.

    Note: When the intracranial pressure gets high enough, it can cause a cranial leak. This is especially true for the Ehlers-Danlos patient where the dura mater is thin and fragile. When a cranial leak decreases the intracranial pressure, the papilledema, empty sella, stenosis, and high-pressure headaches can sometimes start to revert to normal or near-normal, and the leak will affect any attempts to check intracranial pressure (reducing the pressure from what it was before the leak occurred), however, the tonsillar herniation will usually remain if the pressure gets too low. [10]

    TREATMENT OPTIONS:
    If Venous Stenosis exists, stenting should be considered as leaving the sinus/jugular stenosed can post other health risks, and stenting is proving to have much better success with fewer complications requiring revisions. When medication fails to decrease ICP, and a stent is not an option, a Ventriculoperitoneal Shunt (VP Shunt) or Ventriculoatrial Shunt (VA Shunt) can be surgically placed to drain cerebrospinal fluid straight from the ventricle. Shunts are known for failing and often need a multitude of revisions, but even with all the revisions, it is less invasive than a decompression. Shunts under the foramen magnum should never be used as a means of controlling ICP.

    For the IH/IIH patient, herniated tonsils should be assumed an Acquired Chiari Malformation (even if a small posterior fossa is evident), and by correcting the high pressure before decompression, the decompression will be less likely to fail.

    Helpful Tips:
    If you have IH/IIH, it is best to avoid caffeine, avoid progestin based birth control, and all EDS patients should try to avoid the use of fluoroquinolones such as ciprofloxacin (Cipro), levofloxacin (Levaquin/Quixin), gatifloxacin (Tequin), moxifloxacin (Avelox), ofloxacin (Ocuflox/Floxin/Floxacin), norfloxacin (Noroxin), due to the increased risk of aneurysm.

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    References: 

    1 Rangel-Castillo, Leonardo, et al. “Management of Intracranial Hypertension.” Rangel-Castilla, Leonardo et al. “Management of intracranial hypertension.” Neurologic clinics vol. 26,2 (2008): 521-41, x. doi:10.1016/j.ncl. Feb. 2008, <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2452989/>.

    2 Aiken, A.H., et al. “Incidence of Cerebellar Tonsillar Ectopia in Idiopathic Intracranial Hypertension: A Mimic of the Chiari I Malformation.” American Journal of Neuroradiology; Nov. 2012, <http://www.ajnr.org/content/33/10/1901>.

    3 Mokri, B. “The Monro-Kellie Hypothesis: Applications in CSF Volume Depletion.” Neurology., U.S. National Library of Medicine, 26 June 2001, <https://www.ncbi.nlm.nih.gov/pubmed/11425944>.

    4 Zhou, D., et al. “Intracranial hypertension induced by internal jugular vein stenosis can be resolved by stenting.” European Journal of Neurology, November 2017 <https://onlinelibrary.wiley.com/doi/abs/10.1111/ene.13512>.

    5 Henderson, Fraser C., et al. “Neurological and Spinal Manifestations of the Ehlers–Danlos Syndromes.” American Journal of Medical Genetics Part C: Seminars in Medical Genetics, 21 Feb. 2017, <www.onlinelibrary.wiley.com/doi/10.1002/ajmg.c.31549/full>.

    6 Pietrangelo, Ann. “Empty Sella Syndrome.” Healthline, Oct. 2017, <https://www.healthline.com/health/empty-sella-syndrome>.

    7 Hingwala, Divyata R., et al. “Imaging signs in idiopathic intracranial hypertension: Are these signs seen in secondary intracranial hypertension too?.” Annals of Indian Academy of Neurology vol. 16,2: 229-33. doi:10.4103/0972-2327.112476, June 2013, <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3724081/>.

    8 Mollan, Susan P., et al. “A practical approach to, diagnosis, assessment and management of idiopathic intracranial hypertension.” Practical neurology vol. 14,6: 380-90. doi:10.1136/practneurol-2014-000821. May 2014, <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4251443/>.

    9 Thurtell, Matthew J., and Michael Wall. “Idiopathic Intracranial Hypertension (Pseudotumor Cerebri): Recognition, Treatment, and Ongoing Management.” Current Treatment Options in Neurology, U.S. National Library of Medicine, Feb. 2013, <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3554852/>.

    10 Pérez, Mario A., et al. “Primary spontaneous cerebrospinal fluid leaks and idiopathic intracranial hypertension.” Journal of neuro-ophthalmology : the official journal of the North American Neuro-Ophthalmology Society vol. 33,4: 330-7. doi:10.1097/WNO.0b013e318299c292, Dec. 2014, <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4040082/>.