Degenerative Disc Disease

Understanding Your Head and Neck Pain

Published: 28 December 2022
Written by sug_97
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Categories: Atlantoaxial Instability, Cerebellar Ptosis, Comorbidities, Craniocervical Instability, Degenerative Disc Disease, Dysautonomia, Ehlers-Danlos Syndromes, Etiological Co-Factors, Heritable Disorders of Connective Tissue, Intracranial Hypertension, Intracranial Hypotension

You Might Have More Than A Migraine If…

High-Pressure Headaches

Those that suffer from high pressure tend to feel pressure behind the eyes (often mistaken for sinus headaches) and report feeling like their “head is going to explode” from the pressure. High-pressure headaches are generally characterized by being worse when laying down – often awaking in the middle of the night or first thing in the morning with a headache, and the headache tends to dissipate to some degree after being upright for a period of time (and that period of time is different for everybody). Caffeine generally exacerbates high-pressure headaches.

High pressure headaches are typically worse when you lay down and relieved by being upright.
  • For more on Intracranial HYPERtension: http://chiaribridges.org/brain-pressure-understanding-intracranial-hypertension/
  • For a list of common high-pressure symptoms:: http://chiaribridges.org//glossary/symptoms-of-intracranial-hypertension/.

Low-Pressure Headaches

Those that suffer from low-pressure headaches tend to report feeling like there is an invisible pressure pushing down from the top of the head, often making it feel like your “head is going to implode.” Low-pressure headaches are characterized by being worse when upright and relieved by laying down. Low-pressure headaches are typically a sign of a cerebrospinal fluid leak (CSF Leak). The longer that the leak has existed, the less obvious the positional element is – meaning the patient can be upright longer before they feel the pressure at the top of their head, and they tend to need to lay down longer before getting any measure of relief. Caffeine often helps relieve low-pressure headaches.

Low pressure headaches are typically worse when upright and relieved by laying down.
  • For more on Intracranial HYPOtension & CSF Leaks: http://chiaribridges.org//cerebrospinal-fluid-leaks/
  • For a list of common low-pressure symptoms:: http://chiaribridges.org//glossary/symptoms-of-intracranial-hypotension/

Occipital Headaches

Chiari headaches are felt at the occiput – at the base of the back of the skull and upper neck. They are generally tussive in nature, where they are exacerbated by valsalva maneuvers, which generally include: coughing, sneezing, heaving, laughing hard, or bearing down (like with a bowel movement or childbirth). These maneuvers reduce cardiac output (the amount of blood coming from the heart with each heartbeat), which in turn affects the attempted flow of cerebrospinal fluid, and it increases vagal stimuli.

Occipital headaches occur at the back of the lower skull (occiput) and upper neck, on one or both sides of the upper spinal cord.
  • For more on Chiari Malformation: http://chiaribridges.org//chiari-malformation/
  • For an expansive review of the name and definition of Chiari Malformation: http://chiaribridges.org//whats-in-a-name-chiari-malformation/

Connecting the Three Headaches

  • Untreated high pressure can cause cranial leaks (which leads to low pressure) – often accompanied by cerebrospinal fluid leaking through the nose or ears.
  • CSF leaks can sometimes seal on their own leading to rebound high pressure (which is temporary) or continued high pressure if they originally had high pressure.
  • Untreated high pressure can push the cerebellar tonsils down into the foramen magnum where it blocks the flow of cerebrospinal fluid, leading to occipital headaches (often diagnosed as a Chiari 1 Malformation) AND in return, the blockage of cerebrospinal fluid further increases intracranial pressure.
  • Untreated low pressure can cause the brain to sag and as it sags the cerebellar tonsils can get lodged into the foramen magnum where it blocks the flow of cerebrospinal fluid, leading to occipital headaches (often diagnosed as a Chiari 1 Malformation).
  • Untreated spinal leaks can create a suctioning or pulling down effect where the cerebellar tonsils can get lodged into the foramen magnum where it blocks the flow of cerebrospinal fluid, leading to occipital headaches (often diagnosed as a Chiari 1 Malformation).
  • All of the above is most common in patients with a connective tissue disorder such as Ehlers-Danlos Syndrome.

Major Problem Regarding Our Diagnoses & Treatment Options:

  1. Doctors and radiologists alike, tend to see the herniated tonsils and assume a small posterior fossa.
  2. Most do not check for high pressure or low pressure, even when directly asked and symptoms are present.
  3. When a posterior fossa decompression is finally offered, the high or low pressure is often left untreated which leads to a failed decompression.
  4. By the time sufferers get a name to go with their symptoms, we jump at the opportunity for relief.

The “Bobble-head Sensation” – When It Feels Like Your Neck Can No Longer Hold Up Your Head

While most of us experience this feeling either intermittently or continuously, it is generally related to structural instability issues:

  • Craniocervical Instability (CCI, also known as Syndrome of Occipitoatlantialaxial Hypermobility) involves vertical hypermobility (back and forth sliding) of the craniocervical junction (interface between the occipital bone and the 1st and 2nd vertebrae), where the neck is no longer properly supporting the cranium. This condition can be dangerous as it often involves brain stem compression that can lead to a vast array of symptoms of Dysautonomia (dysfunction of the Autonomic Nervous System – ANS).
  • For more on Craniocervical Instability and Other Related Disorders: http://chiaribridges.org/craniocervical-instability-related-disorders/
  • For a list of common CCI symptoms: http://chiaribridges.org//glossary/symptoms-of-craniocervical-instability/
  • For a list of common AAI (a condition commonly seen with CCI) symptoms: http://chiaribridges.org//glossary/symptoms-of-atlantoaxial-instability/
  • Subaxial Instability (SAI; also known as Cervical Instability) involves hypermobility of the C2/C3 to the C7 intervertebral discs. This condition (like most conditions involving the cervical spine) is a major cause of muscle spasms (in the neck and throughout the body at any point below the disc issues. When these neck spasms occur, they can cause the “Bobble-head sensation” where it feels like your neck can no longer hold up your head. This disc degeneration can lead to paralysis as discs compress the spinal cord.

Important Questions to Ask Your Neurosurgeons: http://chiaribridges.org/important-questions-for-your-neurosurgery-appointment/

Originally written 10/2019
Updated 12/2022

From The Inside Out – Understanding Syringomyelia & Syringobulbia

Published: 26 February 2021
Written by sug_97
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Categories: Acquired Chiari Malformation, Comorbidities, Degenerative Disc Disease, Dysautonomia, Syringomyelia

WHEN A DOCTOR TALKS ABOUT THE “MOST SERIOUS” COMPLICATIONS SURROUNDING CHIARI MALFORMATION, THEY USUALLY SPEAK OF PARALYSIS OR DEATH. WHILE BOTH OF THESE ARE FAR LESS COMMON THAN THE ARRAY OF OTHER SYMPTOMS AND COMPLICATIONS, THEY BOTH CAN INVOLVE THAT OF A SYRINX.

The word syrinx (seer-inks), plural syringes  (seer-en-geez), means cavity or cyst. Syringomyelia (seer-ingo-my-el-lee-uh) is when the cyst forms in the spinal cord (myelo usually refers to the spinal cord), and when the cyst is in (or ascends up into) the bulbar region of the brainstem (the medulla oblongata) it is called Syringobulbia (seer-ingo-bulb-e-uh). While these cysts are technically the same cerebrospinal fluid-filled cysts, because they are damaging a different part of the body (each with a completely different function), the location of the syrinx has everything to do with the symptoms that it can cause.

Hydromyelia:
At the center of the spinal cord, there is a hole known as the central canal which runs from the fourth ventricle down the length of the cord. Its role is to carry a microscopic amount of cerebrospinal fluid down the center of the cord from the fourth ventricle. The small amount of fluid in the central canal is usually considered normal. When the central canal has too much cerebrospinal fluid coming in from the fourth ventricle it widens the canal and that abnormal widening that follows the central canal is known as hydromyelia (hydro-my-el-lee-uh) or syringohydromyelia (seer-ingo-hydro-my-el-lee-uh).

The Central Nervous System (CNS) is an amazingly complex network. The brain, brainstem, and spinal cord each play a role in communicating to coordinate everything that happens in our bodies (even when no cognitive thought is required). The messages to and from the brain are sent through the brainstem, down through the spinal cord, and out to our nerves. When that signal is blocked, it can cause interruption from that point down. When it’s thin, it interrupts the signal in the middle (gray matter), as it widens it interrupts the signal more and more, so it’s harder to get signal through the cord at the widest point of the syrinx.

The spinal cord runs through a canal known as the spinal canal. The spinal canal holds cerebrospinal fluid that among other things, nourishes the spinal cord and helps protect it from injury. A syrinx is generally known to be caused by a blockage of cerebrospinal fluid, which is why it is most commonly seen amongst those with Chiari Malformation. When the cerebellar tonsils descend into the spinal canal, like a cork the tonsils block the flow of cerebrospinal fluid. Even when the tonsils fail to descend, they can rest on top of the foramen magnum and still block the flow of cerebrospinal fluid (see Chiari Zero below). There are other conditions that can cause similar blockages as well, so it is not exclusive to Chiari malformations. Anything that causes stenosis (narrowing) of the spinal canal (the cord: canal ratio) can also block cerebrospinal fluid and lead to the formation of a syrinx – conditions such as bulging/herniated discs (from degenerative causes or trauma), spinal cysts/tumors, edema/inflammation of the spinal cord or surrounding membranes (from trauma or conditions like meningitis/arachnoiditis), and/or irregular curvatures of the spine (scoliosis).

Syringomyelia:
Syringomyelia does not usually run the entire length of the spinal cord like the central canal (but it can). Instead, it often seems to spontaneously appear. As the CSF increases in a syrinx, it can either lengthen or widen. The length doesn’t matter much (radiologists note the location because they report what they see and try to be precise). But a neurosurgeon that knows about syringes, knows that what really matters is the diameter of a syrinx (which is where the risk of paralysis can come into play). Symptoms tend to vary based on where the syrinx is located in the spinal cord. The highest point of the syrinx (where the initial disruption starts) and the widest point of the syrinx (location of the greatest disruption) should always be considered because there are different nerves branching from the spinal cord at different intervals. A syrinx interrupts the communication from the top of the syrinx down, so a syrinx that is higher in the spinal cord can have an impact on a larger range of the body. Someone with a syrinx in the lumbar region of the spinal cord will usually have communication problems from the waist down, but someone with a cervical syrinx is likely to have problems from the neck down. A syrinx in the upper thoracic spinal cord (or above) will often include the arms since the peripheral nerves that lead to the arms branch off around the T1 vertebra. The wider the syrinx, the greater the interruption of communication. Therefore, a syrinx should always be gauged by its diameter and not its length. Symptoms generally include (from the syrinx down): muscle weakness, pain, and spasms in legs; pain, tingling, burning of arms; muscle wasting (atrophy); loss of reflexes; loss of pain senses, loss of temperature sensation, numbness, pain, and stiffness in back/shoulders/upper chest (cape-like area); stiffness of muscles; muscle contractions (fasciculations); bowel & bladder dysfunction; scoliosis; paralysis (rare).

Syringobulbia:
Syringobulbia exists when a syrinx forms in the medulla oblongata (the bulbar region of the brainstem) OR when a syrinx in the cervical cord extends upward into the medulla. A syrinx in the medulla can cause medullary issues or in extreme cases, death (since the medulla is responsible for things that happen autonomically (automatically) for survival – such as breathing, heart rate, swallowing, gag reflex, etc.). Dysautonomia is an umbrella term used to describe any dysfunction of the Autonomic Nervous System (ANS), both Sympathetic and Parasympathetic divisions, often accompany any damage to the medulla. When talking about Dysautonomia, many tend to think of Postural Orthostatic Tachycardia Syndrome (POTS), but POTS is but one symptom of Dysautonomia in a long list. The damage from Syringobulbia is not generally isolated to the medulla, but to the cervicomedullary junction (where the cervical spine meets the medulla), it can also affect the cranial nerves causing symptoms such as facial sensory loss (unilateral or bilateral); extraocular muscle palsy; nystagmus; palatal palsy; atrophy of the tongue; dysphonia (vocal cord paralysis); slurred speech; indistinct speech; drooling; tongue fibrillation; oropharyngeal dysphagia; impaired gag reflex; hearing loss; tinnitus (ringing in the ears); alveolar hypoventilation; Sleep-Disordered Breathing (SDB); Central and obstructive sleep apnea; Anhidrosis (inability to sweat normally); Inability to burp (Retrograde Cricopharyngeal Dysfunction – RCP-D).

Common Treatment Options:

Monitoring The Syrinx:
Both Syringomyelia and Syringobulbia tend to be progressive, but in some cases, patients report having no symptoms and imaging proves it to be relatively stable in size. In this case, monitoring is generally recommended. A neurologist or neurosurgeon should carefully monitor these patients to track changes in the diameter of the syrinx (which should include regular imaging) and/or any evolution in related symptoms.

Surgical Treatment Of The Underlying Cause:
For symptomatic patients, or when the syrinx is progressing in diameter, or when the syrinx is so wide in diameter that it is stretching the diameter of the spinal cord from the inside out, treatment is essential. This generally involves treating the cause of the blockage of cerebrospinal fluid. When syrinx exists in a symptomatic patient with Chiari Malformation, a posterior fossa decompression surgery is usually recommended, with the desired result being to re-establish the flow of the cerebrospinal fluid to the spinal canal (so it no longer reroutes to the spinal cord and/or low-lying medulla).

Surgically Draining The Syrinx:
A surgical shunt is commonly used to surgically treat a syrinx when: the underlying cause is unknown or when treating the underlying cause has proven ineffective at reducing the size of the syrinx in a patient that is symptomatic.

Overview: Chiari Comorbidities & Etiological/Pathological Cofactors

Published: 10 December 2020
Written by sug_97
No comments
Categories: Acquired Chiari Malformation, Atlantoaxial Instability, Comorbidities, Craniocervical Instability, Degenerative Disc Disease, Dysautonomia, Ehlers-Danlos Syndromes, Etiological Co-Factors, General Information, Heritable Disorders of Connective Tissue, Intracranial Hypertension, Intracranial Hypotension, Syringomyelia, Tethered Cord Syndrome

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 cofactors 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 brain stem), it is called Syringobulbia, and it comes with a new set of symptoms consistent with the damage being done to the brain stem. 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 cofactor for the syrinx. If more than just the Chiari Malformation is believed to be causing the syrinx, each would be more accurately described as a pathological cofactor.

Dysautonomia occurs when damage has been done to the brain stem 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 cofactor, think of it in terms of a domino effect. Only the first domino is the real etiological cofactor. All of the dominoes in between (on the path) are pathological cofactors. 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

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References: 

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

2 Quake. “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>.

Overview: Chiari Comorbidities & Etiological/Pathological Cofactors [Revised]

Published: 16 November 2019
Written by sug_97
5 Comments
Categories: Acquired Chiari Malformation, Atlantoaxial Instability, Comorbidities, Craniocervical Instability, Degenerative Disc Disease, Dysautonomia, Ehlers-Danlos Syndromes, Etiological Co-Factors, General Information, Heritable Disorders of Connective Tissue, Intracranial Hypertension, Intracranial Hypotension, Syringomyelia, Tethered Cord Syndrome

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: 

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

2 Quake. “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>.