What is Chiari Malformation I?

Chiari Malformation is characterized by the downward displacement of the cerebellar tonsils through the opening of the foramen magnum and is caused by an underdeveloped posterior cranial fossa (PCF). There is no neurological abnormality of the brain or brainstem.

What is the difference between Chiari Malformations I and II?

Quite a bit! CMI is characterized by a malformation of the bone(s) and does not include neurological defects (although, CMI can cause neurological damage because of compression). Type II is correctly referred to as "Arnold Chiari Malformation", "ACMII", "CMII", or "Myelomeningocele". It is categorized as a "neural tube defect" and is often associated with spina bifida. It involves neurological defects and bone malformations.

What are the symptoms of Chiari Malformation I?

Symptoms can vary greatly, especially since there is often nervous system involvement. The most common symptom appears to be headache associated with tense neck/shoulders - although, there have been cases of CMI in which the patient did not have headache as a symptom. CMI presents as a very complex condition and requires a comprehensive medical exam to rule it out. Symptoms of CMI can be very unpredicatable and misleading, to say the least.

Isn't Chiari Malformation I rare?

Most sources do report that the condition is very rare.Studies estimate CMI to be prevalent in about .1 percent of the general population. However, these studies limit the criteria for CMI to cases with tonsillar herniation >5mm below the level of the foramen magnum. More recent medical evidence has proven this criteria much too restrictive. Additionally, it must be kept in mind that CMI has only been diagnosable since the advent of MRI technology in the early 80's. It is, therefore, highly likely that the occurrence of this condition is grossly underestimated.

What should I do if I suspect I have Chiari Malformation?

If you have not yet been diagnosed, consider insurance! Once a diagnosis is made, many insurance companies will refuse to provide coverage for you. Consider getting Short Term Disability insurance from a company such as AFLAC. On the questionaire, be sure to honestly state any symptoms you are having that have been medically documented (headaches, fatigue, etc). IF you are approved for the insurance and have disclosed your symptoms, they cannot refuse coverage based on a pre-existing condition causing those symptoms (be sure to read the policy of any insurance you are applying for, as these things may change). Also, be sure you have a good health plan that will allow out of network medical care should it become necessary. This is especially important for people with minimal cases of CMI - if no other doctor is willing to diagnose your condition, your only option will be to schedule an evaluation at the Chiari Institute in NY (this will be out of network for any medical insurance). Once you've covered yourself, seek out a diagnosis by asking your doctor to have a brain MRI performed and see a neurologist for an evaluation.

I have already had an MRI and my doctor does not believe I have CMI. But, I still believe I may have it - what should I do?

Seek out the advice of a doctor experienced with minimal CMI (see the doctors list). Join a support group such as WACMA (click here) for advice. This board hosts over 2000 members and there are several people who have personal experience with minimal CMI. Again, consider getting health insurance with out of network benefits.

I've tried everything - no one will listen to me!

It's time to educate yourself. It's not uncommon for radiologists and neurologists to overlook cases of CMI with less than 5mm herniation. In cases with less than 3mm, even CMI experts will sometimes refuse to diagnose. The Chiari Institute in New York can provide expert guidance and answers for these more complicated cases.

I cannot afford to go to the Chiari Institute because of insurance limitations. Now what should I do?

If you've exhausted every other effort, a spinal tap may help to reveal elevated ICP. Elevated ICP helps to prove there is a real problem but, it cannot be stressed enough - SPINAL TAPS CAN WORSEN CMI! Do your research before considering such a measure. Even if a spinal tap reveals elevated ICP, treatment for PTC (instead of CMI) may be recommended by your doctor. Be sure to talk with your doctor and choose an appropriate treatment that will not worsen a potential case of CMI!

Is CMI genetic?

There are studies ongoing now at Duke University. Although no definitive proof has yet to be found, there is strong circumstantial evidence that CMI is hereditary. CMI can be a very subtle condition - unnoticed until one is more aware of it's symptoms. People diagnosed with CMI often report noticing "CMI-like" symptoms in family members that they never noticed before their own diagnosis.

What is Syringomyelia?

Often called Syrinx, this refers to pockets of fluid that build up inside the spinal cord (as an analogy, imagine injecting water into a hotdog with a needle). Syrinx can develop as a result of trauma or obstruction (such as CMI). In the case of obstruction, it is elevated pressure of cerebral spinal fluid that forces the formation of these "pockets" of fluid. Syrinx is very painful and can lead to irreversible spinal cord damage if left untreated. MRI's are used to detect Syrinx but, are not 100% accurate. Most doctors strongly recommend surgery if syrinx is found - even if the patient has no complaints of pain.

Should I be tested for Syringomyelia?

If you are diagnosed with CMI, PTC, or any condition related to elevated intracranial pressure, it is a good idea to request MRI's of the entire spine: cervical, thoracic, and lumbar regions. Keep in mind that syringomyelia (syrinx) can be missed on an mri.

What is the best treatment for CMI?

It depends on the severity of each individual case. If neurological damage is a concern, surgery may be the best choice. If symptoms are mild, a diuretic medication may be prescribed to relieve intracranial pressure.

Why are my symptoms worse on some days, and better on others?

Much of it has to do with blocked flow and intracranial pressure(ICP) - which can vary from day to day with CMI. CMI creates an obstruction of CSF flow around the brain which can contribute to elevated ICP. Also take into consideration the blood volume in the head which greatly affects your intracranial pressure (increases naturally when you have been lying down for hours).  According to respectable sources, the cranial cavity contains 80% tissue, 12% blood, and 8% CSF.  Each day, symptoms will vary - based on how much blood and CSF has accumulated in the cranial cavity.  Naturally, there may be more accumulation of blood in the cranial cavity while in a lying position (this explains why some people feel worse upon waking).  After waking, blood volume in the head is reduced again (due to your upright position).  Many CMI sufferers have reported that elevating the head of their bed by 6" brings great relief.  On the contrary, many CMI sufferers report feeling better when lying down.  The particular reason for this is unknown but, perhaps it is due to less pressure exerted on the brainstem by the cerebellar tonsils in the lying position.

My blood pressure is low. Does this mean it is unlikely I have CMI?

Not at all! The blood pressure you are referring to is arterial blood pressure. This is the blood pressure that is measured during a typical doctor's office visit - it is the blood travelling AWAY from the heart (to the brain and other organs). Actually, it is quite common for a CMI patient to report low blood pressure. CMI patients often have problems with venous drainage from the cranial cavity. As a result, the pressure inside the brain's venous sinuses, (Central Venous Pressure or CVP), becomes high. When venous drainage is compromised, it can contribute to low cardiac input (preload). Naturally, when the heart has low input, it's output (afterload) becomes low as well - hence, low blood pressure.

How do I know if my Central Venous Pressure is high?

Unfortunately, determining CVP is not as easy as monitoring arterial blood pressure. To get an accurate measurement of CVP, a catheter is inserted into a vein leading directly to the heart. This is a very invasive procedure and should only be performed when absolutely necessary.