By BRANT RICHARDSON, PA-C

Thank you for taking the time to investigate this web page. Our goal is to raise your awareness about Chiari malformation in hopes that it will be included in the differential diagnosis of your patients with headaches and neurologic symptoms.

Dr. Hans Chiari, an Austrian pathologist, is credited with describing the malformation in 1891. The condition occurs when a malformation of the posterior fossa of the skull leaves inadequate space for the cerebellum. This causes herniation of the cerebellar tonsils through the foramen magnum. This displacement compresses the cerebellum, medulla and spinal cord. The crowding through the foramen magnum can disrupt the normal flow of CSF as well. The condition has been broken into four subtypes. Type I is the most common and least severe. Although it is usually congenital, it is sometimes not symptomatic until adulthood and is rarely fatal. In Type II, there is a larger herniation of the cerebellum which can lead to restricted flow of CSF and hydrocephalus. It is usually diagnosed at birth or prenatally and is associated with a myelomeningocele. There is early onset of symptoms in Type II and a 33% mortality rate. Types III and IV are of less clinical significance because they are very rare and are usually fatal by age two to three. Although severity increases with each type, it does not appear that it is simply a continuum of the same deformity.

The symptoms of Type I Chiari malformation can be similar to other disorders and can vary greatly from one patient to the next, making diagnosis difficult. The hallmark of this problem are headaches and neck pain, made worse by valsalva, coughing, sneezing and straining. The intensity of headaches and cervical pain can be completely debilitating. Fatigue is common and, as the condition progresses, patients may develop vertigo, tinnitus, nausea, dysphagia, impaired gag reflex, muscle weakness, poor coordination, restless legs, upper extremity paresthesia, dysautonomia and, in severe cases, paralysis. Often patients are diagnosed with fibromyalgia or chronic fatigue syndrome, which delays diagnosis of Chiari malformation. This is unfortunate because surgery can be very effective.

Recognizing the varying symptoms of Chiari is difficult so it is important to keep your suspicion high. During the physical exam, look for any deficits in fine motor skills and the lower cranial nerves. For the most part though, early diagnosis is made by history and MRI. If the MRI shows a Chiari malformation, refer the patient to a neurologist or neurosurgeon for treatment. Posterior fossa decompression surgery involves removal of the inferior portion of the occipital bone as well as the lamina of C1 and possibly C2-3. The dura mater must be opened to allow the cerebellum to expand into the space so a dural graft must be placed. In 80% of the patients, the procedure successfully eases or prevents further progression of symptoms. We continually update our Doctor Directory, which is a compilation of neurosurgeons who perform posterior fossa decompressions, arranged by the state and country where they are located. There is no cure for Chiari. The sooner treatment begins, the less permanent nerve damage occurs and the earlier patients can get back to a productive life. For many patients, just having a diagnosis  with an anatomical description is a great relief.

As we have come in to the MRI era, it has been found that Chiari malformation is not nearly as rare as it was previously thought. Incidence is estimated at one per 1,000, though not all are symptomatic. There are roughly 300,000 people diagnosed with Chiari in the United States. As awareness of the problem grows and access to MRIs improves, that number is likely to go up. The cause of Chiari is unknown. It is more common in females, by a three-to-one ratio. There is some evidence that Chiari malformation is hereditary as well.

Part of the motivation of Pete Dal Bello to found the International Chiari Association (ICA) came from the great benefit he had from finally being diagnosed and having posterior fossa decompression surgery. The ICA strives to raise awareness
for early diagnosis, as well as to provide the answers and support that were not in place at the time of Dal Bello's diagnosis. Please ask your patients to visit this web site, as well as our Facebook page and view our Chiari-related videos at the International Chiari Association Network (ICAN). One of the main things that people with Chiari have in common is a tough road ahead, but we truly believe these resources will be a great asset to them.

 Brant Richardson, PA-C, is a medical advisor for the International Chiari Association (ICA).  

(c) 2012 International Chiari Association (ICA).  www.ChiariAssociation.org
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