Exquisite Goods

Category: Tethered Cord Syndrome

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.
September 16, 2023
Spine Pulled Tight – A Guide to Understanding Tethered Cord Syndrome

TETHERED CORD SYNDROME (TCS) INVOLVES A STRETCHING OF THE SPINAL CORD, AND OFTEN YOUR MEDULLA OBLONGATA
AS WELL, WHICH LEADS TO A HOST OF NEUROLOGICAL PROBLEMS.

Before we talk about Tethered Cord Syndrome, let’s first talk about the anatomy associated with the spinal column (in layman’s terms).

• The role of the vertebral column is to hold the spine strong (so it can be upright) and protect the spinal cord from injury. In a normal vertebral column, there are thirty-three vertebrae on each side (seven cervical vertebrae, twelve thoracics, five lumbar, five fused vertebrae in the sacrum and another four fused vertebrae in the coccyx).

• Each vertebra in the upper twenty-four vertebrae is separated by intravertebral discs largely composed of the fibrous protein, collagen. The main role of these discs is to allow the vertebral column to move and flex.

• The role of the spinal canal is to hold cerebrospinal fluid around the spinal cord, which not only cushions the cord against injury, but it also lubricates the cord, cleanses the cord, and brings essential nutrients that the spinal cord needs. The spinal canal is made up of several layers that form the meninges. These layers are also composed of high concentrations of collagen. The outermost layer of the meninges is the dura mater. The dura mater should be dense and strong, so cerebrospinal fluid cannot leak from it.

• The spinal cord relays messages from the brain to the nerves that allow the body to function. When part of the spinal cord is compromised, it can inhibit signals from getting to the nerves from that point downward. The brainstem (midbrain, pons, and medulla oblongata) is attached to the spinal cord at the top (the medulla and spinal cord meet at what is called the cervicomedullary junction) and the spinal cord continues down to the mid/lower back. From there it becomes a delicate elastic band of fibrous collagen-based tissue called the filum terminale that extends from the conus medullaris (the lowest point of the spinal cord before it becomes the filum terminale) to the dural sac at the S2 level.¹

Chiari Malformation has many conditions that can be associated with it (comorbid conditions) and sometimes those comorbid conditions can be at the root cause (etiological cofactor) or one of the causes along the way (pathological cofactor) to the tonsils being as low as they are (making the Chiari “secondary” to one or more “other” conditions). Tethered Cord Syndrome (TCS) is one of those pathological conditions.² Like Chiari, it is a neurological disorder; however, it is one of the spinal cord.³

Tethered Cord happens when the sticky fibrous tissue of the filum adheres to fatty/scar tissue or the dura lining of the spinal canal.¹ While this tethering can happen anywhere in the spinal canal, it is most common at the lumbosacral level.⁴ When the tethered filum pulls the spinal cord tightly enough that it causes neurological problems, it becomes known as Tethered Cord Syndrome (TCS). Tethered Cord is most common in patients with Spina Bifida (myelomeningocele, meningocele), Spina Bifida Occulta (lipomeningomyelocele, lipomyelocele) and patients with Ehlers-Danlos Syndromes (EDS), a Hereditary Disorder of Connective Tissue (HDCT) where one or more of the types of collagen (the most abundant protein in the human body) is mutated at a cellular level. Tethered cord can be congenital or acquired. It can be obvious in childhood or symptoms may not present themselves until adulthood. Some children may develop minor signs that are overlooked by untrained medical professionals and can progress slowly or rapidly over time.

More Symptoms of Tethered Cord Syndrome

A Tethered Cord Syndrome diagnosis can be somewhat of a challenge. The signs and symptoms of the condition are not always present and when they are, they are often not recognized, so it is important to know all indicators. People with Tethered Cord (TC) can have sacral dimples, discoloration, and hairy patches on their lower back that can lead a doctor to investigate further, however, some have no external signs at all. Some have kyphosis (rounded back) and scoliosis (curved spine). Sometimes radiological criteria are not met or are ambiguous, yet an Occult Tethered Cord (characterized by the presence of symptoms with normal conus position and inconclusive findings of the filum) can still exist.⁵ Symptoms can be elusive as well and can happen all at once or gradually over the course of many years. Many symptoms worsen due to activity; climbing stairs has been reported as causing pain that varies from uncomfortable to excruciating.

One of the reasons that Tethered Cord is often overlooked is that many neurosurgeons are not aware of the connection it can have with a Chiari Malformation and the medical tests used for determining if a tethered cord problem exists are not always accurate or accurately read.

Magnetic Resonance Imaging (MRI)

• A lumbar MRI is usually the first step. This gives a visualization of the spinal cord in relation to the surrounding vertebrae. The actual tethering is not always obvious on MRI, sometimes the only proof of the tethering is the pulling it creates on the spinal cord. Doctors will look for the position of the conus medullaris when looking for signs that the spinal cord is being pulled. The consensus amongst most surgeons is that a normal conus should be located from the T12 to the lower L2. There is much debate on the importance of establishing evidence of a low-lying conus.⁵When conus reaches the lower L2 or below, doctors should be investigating why it’s low and consider if the cord might be tethered. When looking for the location of the conus, your position can make all the difference. MRIs are generally performed supine (lying down) and the cord is not pulled as tightly as it is when upright. For this reason, upright MRIs are becoming the method of imaging preferred by most neurosurgeons looking to confirm or deny if tethering exists in a patient showing symptoms. Other signs of tethering that might be visible in a lumbar MRI include an enlarged foramen magnum, thick or fatty filum, presence of fatty tissue inside the canal, or the filum might be pulling to one side of the canal.⁵

• A prone MRI of the lumbar region can be an invaluable tool for those where other MRIs indicate that the filum might be pulling to one side (usually the back side) of the canal. With prone MRIs, imaging is done while the patient is lying face down (as opposed to facing up, like most supine MRIs). If the anteroposterior conus movement of >10% of the canal width was evident from the supine to the prone, then the likelihood of it pulling to one side do to tethering is less likely and more conservative management might be better appropriate than a surgical release.⁶

• A cervical MRI can also show signs that a tethered cord might exist. The cervical spinal cord can sometimes appear narrow from it being pulled tight. The medulla oblongata can become elongated. This happens because the brainstem is attached to the top of the spinal cord and that cord is being pulled tight, essentially pulling everything down and tight. This elongation of the medulla from the tethering can cause secondary symptoms by itself, known as Dysautonomia.

· Low/herniated cerebellar tonsils consistent with what is seen in a Chiari Malformation. When the brainstem is herniated (where part/most of the medulla is below the foramen magnum) along with the cerebellar tonsils, it is considered a Chiari 1.5 (which should be a good indicator that you might be dealing with an Acquired Chiari Malformation, where the herniated tonsils are secondary to another condition). One study quoted that out of 2,987 patients with a tonsillar herniation of 5mm or greater, 14% met the diagnostic criteria (based on “generally accepted clinical and radiographic criteria”) and 63% of the 289 patients with tonsillar herniations of < 5mm.⁵

· A syrinx is common with Tethered Cord, as it causes a blockage of fluid at the foramen magnum. A syrinx can develop anywhere in the spine, usually in the lower cord, but with Tethered Cord Syndrome it can develop in the lower medulla (Syringobulbia) as well because of the low brainstem is at the point of the blockage of fluid from the Chiari Malformation.

Even with an upright MRI and every symptom listed, patients are often told they do not have Tethered Cord. This is simply due to a lack of education on the subject and medical bias between doctors. It is important to make sure that you have the images viewed by a neurosurgeon that is familiar not only with Tethered Cord but Chiari and Comorbids as well. (Nearly half of the large study quoted above were referred following a failed Chiari Decompression.⁵) The combination of the images and the patient’s symptoms should tell the neurosurgeon if surgical intervention is required. Patients often require several consultations before they can find a knowledgeable enough physician.

What We Recommend BEFORE DECOMPRESSION is considered:
If you have symptoms of TCS, especially if accompanied by any of the MRI indicators mentioned above, it is both reasonable and prudent to ask your neurosurgeon to investigate further before decompression is considered. A Tethered Cord Release Surgery prior to decompression may relieve the tension that is pulling the brainstem and cerebral tonsils downwards reducing the risk of a failed decompression. There is a chance with small tonsillar herniations that the Tethered Cord Release might allow the cerebellar tonsils to rise enough to the point that cerebrospinal fluid flow is reestablished to where decompression is no longer needed. However, failure to release a tethered cord prior to decompression surgery increases the likelihood of a failed decompression. (In fact, in the study quoted above, out of the 3,276 patients with herniated tonsils, 46% of them were referred for evaluation after a failed decompression surgery.⁵) An MRI of all three levels of the spine should be done to rule out other possible causes for leg/back symptoms along with urodynamic testing, an Electromyogram (EMG) Test and Nerve Conduction Study (NCS) of the lower limbs is also suggested.

TREATMENT OPTIONS:
For some, physical therapy can help with symptoms for a while. However, ultimately it will likely need to be surgically treated with a Tethered Cord Release.

Tethered Cord Release (TCR) Surgery involves the untethering of the spinal cord. An incision is made in the lumbar area, the filum terminale is separated and the factors that are tethering the spinal cord to the vertebrae are severed. Surgical treatment is not without risk and does not guarantee relief of symptoms. However, in a large study, up to 83% of adult patients report relief, 16% unchanged, and 1% report feeling worse.⁵ In children, the numbers are even better with 93% obtaining improved symptoms and 7% unchanged.⁵ Most patients describe the surgery as extremely painful for the first two weeks and “better than they ever remember feeling” (often because they have been tethered for much of their lives) after two weeks. The most common complication involves retethering (often from the scar tissue from the release) and multiple surgeries may be required over a lifetime. Finding a neurosurgeon experienced with TCRs and the surgical treatment of Ehlers-Danlos patients can sometimes help reduce the risks associated with scar tissue formation, but scar tissue can happen with even the best of neurosurgeons.

For the TCS patient, herniated tonsils really should be assumed an Acquired Chiari Malformation (even if a small posterior fossa is evident), and by correcting the tethered cord before decompression the decompression will be less likely to fail.

Special Note: There are other conditions that can present with similar symptoms. Diastasis Recti is a type of abdominal hernia common to pregnant women, those with obesity, and EDS patients. This separation in the abdominal muscles is known to sometimes cause lower back pain and many of the same pelvic floor problems seen with Tethered Cord Syndrome (TCS). Unlike TCS however, it does not usually require surgical treatment. If you suspect Diastasis Recti, we recommend that you talk to your Primary Care Physician about referring you to physical therapy to bring your abdominal muscles back together before considering Tethered Cord Release (TCR).⁷

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References:

¹ 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>.

² “Section of the Filum Terminale Surgery for Tethered Spinal Cord Syndrome in Patients with Chiari Malformation and Syringomyelia.” North Shore-Long Island Jewish Health System The Chiari Institute, Chiari Connection International, 02 Oct. 2006, <http://www.chiariconnectioninternational.com/docs/TCS_SFT_Explained.pdf>.

³ Quake. “Overview: Chiari Comorbidities & Etiological/Pathological Cofactors [Revised].” Chiari Bridges, 16 Nov. 2019, <http://chiaribridges.org/overview-chiari-comorbidities-etiological-pathological-cofactors/>.

⁴ Arslanoglu, A., et al. “Multidisciplinary Combined Approach for Tethered Spinal Cord Syndrome: Radiology, Surgery and Physical Therapy.” Balkan Military Medical Review, 2006, <https://pdfs.semanticscholar.org/8c30/18bf5bfbd6f3e7e5e9c3559bbbfdcac82e04.pdf>.

⁵ Milhorat, Thomas H., et al. “Association of Chiari malformation type I and tethered cord syndrome: preliminary results of sectioning filum terminale.” Surgical Neurology, Elsevier, July 2009. <https://www.sciencedirect.com/science/article/abs/pii/S0090301909002572>.

⁶ Aoun, Salah G., et al. “The Use of Prone Magnetic Resonance Imaging to Rule Out Tethered Cord in Patients With Structural Spine Anomalies: A Diagnostic Technical Note for Surgical Decision-making.” Cureus vol. 11,3 e4221. 11 Mar. 2019, doi:10.7759/cureus.4221. <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6510567/>.

⁷ “A Complete Guide to Diastasis Recti: Truths on Abdominal Muscle Separation.” Braceability, 05 June, 2018. <https://www.braceability.com/blogs/info/diastasis-recti>.

December 6, 2019
Overview: Chiari Comorbidities & Etiological/Pathological Cofactors [Revised]
When you start to educate yourself on a condition like Chiari, your vocabulary will be challenged. Most of us study with a medical journal article opened in one tab and medical dictionary in the next. Amongst all the medical terminology you will tackle, there are probably a few terms as important to your understanding of Chiari than comorbidities and pathological/etiological cofactors. When two or more conditions tend to co-occur, they are said to be comorbid with one another. It makes no inferences of a causal relationship between the conditions, only that they co-occur. This co-occurrence deduces that a correlation exists, but when the nature of that correlation is not known, they are just said to be comorbidities. When a “causal relationship” is known or suspected, the conditions start being discussed in terms of pathology or etiology, which are similar, but not exactly the same thing.

An etiological cofactor exists when the “root cause” of a condition is known or believed to be known. That “root cause” is the etiological cofactor. When an etiological cofactor can cause a series of events or conditions that can become “direct causes” for other conditions, that series of events creates a pathology. Conditions along the path are called pathological cofactors. Understanding these cofactors is imperative in understanding Chiari and all of the comorbid conditions that accompany it.

ETIOLOGICAL COFACTOR:

Chiari Malformation often seems like a beast that wreaks havoc on our bodies on every level. Indeed it is, but as you can see from the diagram above, it really is not the “root” of everything that is going wrong. There is a bigger beast at work in so many of us, and its name is Ehlers-Danlos. It is not by chance that so many of us with Chiari have so many other conditions in common (especially conditions like Degenerative Disc Disease, arthritis and other connective tissue problems). It is not by chance that so many of us have a history of miscarriage and similar familial histories. It is not by chance that Chiari is more prevalent in females than males. And it is definitely not by chance that Chiari is running in families and they cannot find a definitive genetic link. They cannot find it because they are not looking at the beast hiding in the background.

Ehlers-Danlos Syndromes are a group of inherited disorders involving a genetic mutation in one or more of our bodies’ collagen. Collagen is the most abundant protein, making up 1/3 of the proteins in the human body, affecting our bones, skin, muscles, and connective tissue^[1]. Collagen is often described as a “cellular glue” that helps hold the body together. When that glue fails to hold, everything seems to go awry; before and after birth: skulls can under-develop in utero, organs tend to prolapse, and bones begin to shift as joint laxity increases (including the bones/vertebrae at the craniocervical junction). Ehlers-Danlos is a primary “root cause” of Chiari Malformations and a majority of the other problems we have. The list in blue is far from being a complete list of conditions caused by EDS. They are commonly accompanied with Chiari because they can cause or attribute to a Chiari malformation (pathological cofactors).^[2]

PATHOLOGICAL COFACTORS:

Cranial Settling occurs when the skull has dropped and the odontoid (C2/axis) enters into the foramen magnum (Basilar Invagination). This drop can further compromise the craniocervical junction and as it pushes everything down, it increases the likelihood of an Acquired Chiari Malformation.

Craniocervical Instability (CCI) & Atlantoaxial Instability (AAI) usually occurs with cranial settling and Basilar Invagination (BI). The settling and/or softening of tissue can cause a shifting of the C2 (resulting in CCI or AAI) and the cerebellar tonsils (which are already inclined to prolapse) simply drop down with each shift affecting ones ability to tilt/rotate their head.^[3]

Intracranial Hypertension (IH – High Intracranial Pressure) occurs when your intracranial pressure (ICP) becomes elevated. This elevation can happen for a variety of reasons.
1. Space Occupying Masses (cysts, tumors or hydrocephalus) take up space inside the skull causing a “mass effect.”
2. When no mass effect exists, many doctors look no further and give the diagnosis of Idiopathic Intracranial Hypertension.
Because the area of the skull is fixed in an adult cranium and partially fixed in that of a child, the elements inside the fixed space (CSF, blood volume and brain matter) tend to get pushed out wherever they can (the only place that they can escape without breaking through the dura is through the foramen magnum and the brain matter that’s closest to the foramen magnum is the cerebellar tonsils).^[4]

Tethered Cord Syndrome occurs when the tissue inside the epidermis adheres to the spinal cord or filum terminale. While this tethering can happen anywhere along the spinal canal, it is most common in the lower lumbar and/or sacral spine. When this adhesion happens it creates a pulling down of the spinal cord and consequently, the brainstem located at the top of the spinal cord and the cerebellar tonsils just get pulled down with it.^[5]

Intracranial Hypotension (Low Intracranial Pressure, often involving a CSF Leak) usually involves a cerebrospinal fluid leak or an over-draining shunt, we will highlight the former. Ehlers-Danlos patients tend to have weak dura matter. Tears/holes in the dura can happen anywhere in the dura surrounding the brain or spinal canal and they can happen completely spontaneously (without a known cause). When the leak occurs in the spinal canal, they can create a suctioning effect where cerebrospinal fluid (CSF) is being pulled down and out, causing the intracranial pressure (ICP) to drop. The cerebellar tonsils that are already prone to prolapse (due to EDS) end up getting suctioned downward with the CSF.^[6] Cranial leaks often happen when high pressure is left untreated until the high pressure causes a leak in the dura mater. In cranial leaks, fluid usually leaks through the nose or ears (less common), and you can often taste the metallic taste of the cerebrospinal fluid in the back of your throat. While both spinal leaks and cranial leaks can cause low pressure and low-pressure symptoms, and while both can start, stop, and start again spontaneously, there is an increased risk whenever there is an opening where cerebrospinal fluid leaks outside of the human body (if cerebrospinal fluid can make it out of the body, microscopic bacteria can make it inside the same opening where it can enter in the meninges).^[7]

Posterior Cranial Fossa Hypoplasia (PCFH) is the only etiological cofactor listed above that is definitely congenital. The role of collagen in bone development has been long-standing, especially its known contribution to certain conditions like Osteogenesis Imperfecta. However, more recent studies are discovering the role collagen plays in congenital posterior fossa anomalies. Posterior Cranial Fossa Hypoplasia is the most commonly “acclaimed” cause of Chiari malformations, but studies show, that even when all of the other causes above are factored out, only approximately 52% of those left (that fail to meet “the diagnosis criteria” for any of the above), have a small posterior fossa.^[8]

COMORBIDITIES:

While all of the conditions listed in the diagram are comorbidities, some are etiological/pathological of an Acquired Chiari (even though nearly 100% of us are told that our Chiari Malformation is congenital) and others have Chiari Malformation as their etiological/pathological cofactor:

Syringomyelia occurs when cerebrospinal fluid (CSF) is obstructed and a CSF filled cyst/cavity forms inside the spinal cord. This cyst is directly related to the obstruction of cerebrospinal fluid that can be caused by Chiari Malformation, Spinal Stenosis (a narrowing of the spinal canal, spinal cyst/tumor, a herniated disc), or irregular curvature of the spine (scoliosis). When that cyst/cavity extends into the medulla oblongata (the lowest part of the brainstem), it is called Syringobulbia, and it comes with a new set of symptoms consistent with the damage being done to the brainstem. So when Chiari Malformation exists with a syrinx, and there is no stenosis or disc problem in close proximity below it, the Chiari Malformation should be listed as the etiological condition of the syrinx. If more than just the Chiari Malformation is believed to be causing the syrinx, each would be more accurately described as pathological.

Dysautonomia occurs when damage has been done to the brainstem or Vagus nerve. Whenever either of these is damaged, often from compression at/near the craniocervical junction, the autonomic nervous system can begin to dysfunction.

Confused? If you understand the causal relationships but find yourself wondering if a comorbid condition is an etiological or a pathological, think of it in terms of a domino effect. Only the first domino is etiological. All of the dominoes in between (on the path) are pathological. The important thing to remember in this array of medical terminology is that while everything is definitely not Chiari, it almost always shares a connection to it, and that is why so many of us have so many conditions and symptoms that doctors call unrelated! It is imperative in our fight that we know “what” we have and “why” it is happening. With such a broad spectrum of symptoms (like we all have), we must educate ourselves and not just believe the limited knowledge of our doctors.

*Revised November 2019

References:

¹McIntosh, James. “Collagen: What Is It and What Are Its Uses?” Medical News Today, MediLexicon International, 16 June 2017, <www.medicalnewstoday.com/articles/262881.php>.

²Quake. “The Chiari Malformation Ehlers-Danlos Connection (Short Version).” Chiari Bridges, 7 Dec. 2017, <www.chiaribridges.org/chiari-malformation-ehlers-danlos-connection-short-version>.

³ Hawkeye. “Overview: Craniocervical Instability and Related Disorders.” Chiari Bridges, 6 Dec. 2017, <www.chiaribridges.org/craniocervical-instability-related-disorders>.

⁴ Quake. “Brain Under Pressure – Understanding Intracranial Hypertension.” Chiari Bridges, 10 Dec. 2017, <www.chiaribridges.org/brain-pressure-understanding-intracranial-hypertension>.

⁵ Storm. “The Tethered Cord – Chiari Malformation Connection!” Chiari Bridges, 15 Dec. 2017, <www.chiaribridges.org/tethered-cord-chiari-malformation-connection>.

⁶ Argent. “Overview: Cerebrospinal Fluid Leaks.” Chiari Bridges, 10 Dec. 2017, <www.chiaribridges.org/cerebrospinal-fluid-leaks>.

⁷ 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 (2013): 330-7. doi:10.1097/WNO.0b013e318299c292, <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4040082/>

⁸ Quake. “Overview: Chiari Malformation.” Chiari Bridges, 6 Dec. 2017, <www.chiaribridges.org/chiari-malformation>.
November 16, 2019
What’s In A Name? An Expansive Review of the Name and Definition of Chiari Malformation
THE DEFINITION OF A CHIARI MALFORMATION HAS BEEN LONG DEBATED. IT REALLY IS NO WONDER THAT PATIENTS AND MEDICAL PROFESSIONALS ALIKE ARE CONFUSED. THEN, WITH US FULLY UNDERSTANDING ALL SIDES OF THE DEBATE, WE DEFINED A CHIARI MALFORMATION AS STRUCTURAL DEFECTS IN WHICH THE CEREBELLUM, THE HIND PART OF THE BRAIN, DESCENDS BELOW THE FORAMEN MAGNUM INTO THE SPINAL CANAL. THIS DEBATE IS BEING ANALYZED THIS YEAR, AS CERTAIN ORGANIZATIONS ARE BRAVING TO ATTEMPT TO BRING DOCTORS ALL UNDER ONE UNIFORM DEFINITION AND DIAGNOSTIC CRITERIA. THEREFORE, AMIDST ALL THE CONFUSION AND DEBATE, WE WANTED TO EXPLAIN THE FACTORS INVOLVED, AND WHY WE WENT WITH THE DEFINITION THAT WE DID, AND WHY ONE STANDARD IS SO IMPORTANT!

To better facilitate our explanation, we will call all associated terms by their specific medical names:

Tonsillar Ectopia (TE) = tonsillar herniation of any size
Posterior Fossa Hypoplasia (PFH) = an underdeveloped posterior fossa

Chiari Malformation Vs. Arnold Chiari Malformation

The most common type of Chiari is Type 1 (which includes a Chiari 1.5, where the brainstem is also below the foramen magnum). Many people use the term “Chiari Malformation” when diagnosed with Type 1, while others cling to the name “Arnold Chiari Malformation” with the same diagnosis. Is there a difference? The name “Chiari Malformation” came from Hans Chiari, an Austrian pathologist, who first discovered the malformation in the late 19th century.^{[1, 2]} Julius Arnold, a German pathologist, later expanded on Chiari Type 2, and Type 2 took on his name “Arnold Chiari Malformation.” Therefore, technically speaking, a Chiari Malformation and an Arnold Chiari Malformation are not the same; Arnold Chiari Malformation is specific to Chiari Type 2 (which usually includes a myelomeningocele, the most serious form of Spina Bifida). However, they are used interchangeably by many, even by medical professionals and the misnomer is of little consequence one way or the other.^[3]

Chiari Malformation = Posterior Fossa Hypoplasia Theory

Many ascribe to the theory that a Chiari Malformation ONLY consists of a posterior fossa hypoplasia (which means that the back of the skull is malformed, and therefore the cranial area (space) at the rear is too small). They believe that a tonsillar ectopia is only a symptom, and a Chiari Malformation can exist with or without an accompanying ectopia. This argument is not without merit, because much of what was initially being looked at by Hans Chiari were deformities in the posterior skull upon postmortem examination (so there wasn’t soft tissue to analyze). He originally attributed much to hydrocephalus, but expanded his research into the pons, medulla oblongata, and cerebellum (which can all be attributed to intracranial pressure as a pathology of a “tonsillar ectopia”). To ascribe to this belief would also mean that “Acquired Chiari Malformations” cannot exist, as one doesn’t “acquire” a small posterior fossa. And that would also mean that Chiari Type 2, Type 3 and Type 4 technically would not be a Chiari Malformation at all either, since their definitions do not require a posterior fossa hypoplasia. Perhaps type 3, which has an opening at the back of the skull, but no “small posterior fossa” is even implied in the definitions.

But to look at the full history of what became known as a Chiari Malformation, we can begin by looking at the research of a German pathologist, named Theodor Langhans. In his research in 1881 (a decade before Hans Chiari conducted his research on what became known as a Chiari Malformation), while looking at syringomyelia (“a cavity created in the spinal cord”), he noted a “change in the cerebellar cavity.” Upon dissection of the cerebellum, he described the cerebellar tonsils as “two symmetrical pyramidal tumors,” pushing the brainstem forward.^[4] In fact, the other noted researchers: Nicholas Tulp (1593–1674), John Cleland (1835–1925), and Julius Arnold (1835–1915), all centered on the hindbrain hernia [herniation] without speculation as to its etiology/pathology. It is said that “many of the English translations of Chiari’s work contain inaccuracies.” But note that Chiari’s first paper was on “ectopia of cerebellar tissue,” and that he went on to define Type 1 as showing, “elongation of the tonsils and medial parts of the inferior lobes of the cerebellum into cone shaped projections, which accompany the medulla oblongata into the spinal canal.”^[5] Which sounds like what is now known to be a Chiari 1.5. Much later, in 1938, at a time when the posterior fossa decompression became the popular surgical treatment for a Chiari Malformation, a Chiari 2 patient “underwent posterior fossa exploration with the authors not considering hindbrain herniation in their differential. Penfield and Coburn later stated that: ‘In retrospect it seems that we should have suspected the Arnold-Chiari malformation. Instead, a suboccipital craniotomy was carried out…” So even the early neurosurgeons seeking to perfect their surgical treatment felt that it was a mistake to concentrate on the posterior fossa and not take into account etiologies of the hindbrain herniation. That mistake is still going on 80 years later.^[6]

The biggest problem that they are going to have with strictly defining a Chiari Malformation as a small posterior fossa resides in the fact that the diagnosis criteria for a Chiari Malformation only consists of ONE MEASUREMENT, the length of the tonsillar ectopia (how far the tonsils herniate below the foramen magnum). Generally, there are no measurements of the posterior fossa taken when radiologists make the initial diagnoses. Furthermore, most neurosurgeons see the radiology reports, and depending on symptomology, they make the decision to decompress or not to decompress without ever measuring the size of the posterior fossa. Most never look for (and often do not know about) etiological/pathological cofactors that could have been causing the tonsillar prolapse in the first place.

Where does this assumption leave us?

Unfortunately it leaves most of us with failed decompressions, fighting with our neurosurgeons that “something is still wrong.” These neurosurgeons look at their post-operative checklist and see that they successfully did everything surgically required in their out-of-date textbooks:
1. Suboccipital bone was appropriately decompressed. ✔️
2. Dura was opened and dura patch was successfully inserted. ✔️
3. Lamina was successfully removed from the C1 (and sometimes the C2 as well). ✔️
They did all that was required of them based on the diagnoses presented! They don’t have time (or don’t care) to look beyond that, so once again, the idea of our continued symptoms are thought of as being psychosomatic.

While we applaud the efforts of those seeking to get a measure of consistency in how Chiari is defined, the truth remains that until the diagnosis criteria is changed as well, we are being diagnosed with Chiari Malformation based on our tonsillar herniation; it is presumed to be congenital; we are being surgically treated as though it is congenital, and we are ending up with failed decompressions. This confusion is beyond unacceptable, it’s reprehensible!

When it is all redefined, hopefully we will have a well defined diagnosis criteria, or it is all irrelevant. And the many that really did acquire what was assumed to be “congenital” who are now being told that they do not have Chiari Malformation at all, will be able to get lawyers for “an improper diagnosis” that lead to the incorrect brain surgery being done. There are surgeons coming around and finally seeing that there is merit to these studies that have been done since the late 1990s, that have shown a pushing/pulling effect that can cause the tonsillar ectopia that gets us diagnosed with a Chiari Malformation, and we applaud them for having the integrity to stand up and get it right. That’s exactly what we need and deserve!

If you were diagnosed with a Chiari Malformation and want to know how all of this might be affecting you, we encourage you first to find your initial radiology reports, and see if there were measurements taken of the posterior fossa. And then wait with that information… wait and see what changes are actually made to the definition. While you are waiting learn. Learn everything you can about every etiological/pathological cofactor, and every comorbidity. If it is “officially” redefined as a small posterior fossa, we will have to work together as a community (like we always do) to help lawyers see how we have been getting lost in the shuffle, year after year. If it’s not officially changed and Chiari continues to be defined as a structural defect involving the cerebellar tonsils, we will have to continue in our fight to make these cofactors of Acquired Chiari Malformation known!

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References:

¹ Tubbs, et al. “Hans Chiari (1851–1916).” Journal of Neurology, Pioneers in Neurology, Springer Berlin Heidelberg, 26 Mar. 2010, <https://link.springer.com/article/10.1007/s00415-010-5529-0>.

² “Hans Chiari.” Whonamedit – Dictionary of Medical Eponyms, <www.whonamedit.com/doctor.cfm/1123.html>.

³ Tubbs, R. Shane, and W. Jerry Oakes. The Chiari Malformations: A Historical Context . 2013, <https://pdfs.semanticscholar.org/79dd/127d31820d612600c0b032225437295d86c3.pdf>.

⁴ Mortazavi, M M, et al. “The First Description of Chiari I Malformation with Intuitive Correlation between Tonsillar Ectopia and Syringomyelia.” Advances in Pediatrics., U.S. National Library of Medicine, Mar. 2011, <https://www.ncbi.nlm.nih.gov/pubmed/21361763>.

⁵Pearce, J M S. “Arnold Chiari, or ‘Cruveilhier Cleland Chiari’ Malformation.” Journal of Neurology, Neurosurgery & Psychiatry, BMJ Publishing Group Ltd, 1 Jan. 2000, <https://jnnp.bmj.com/content/68/1/13>.

⁶Mortazavi, Martin M., et al. “The First Posterior Fossa Decompression for Chiari Malformation: the Contributions of Cornelis Joachimus Van Houweninge Graftdijk and a Review of the Infancy of ‘Chiari Decompression.’” SpringerLink, Springer, Dordrecht, 6 Apr. 2011, <https://link.springer.com/article/10.1007%2Fs00381-011-1421-1>.
September 4, 2018