Chiari Malformation Type 1

What is a Chiari Malformation?
A Chiari malformation is a relatively rare abnormality where the cerebellum (lower part of the brain) is displaced below the level of the foramen magnum (hole in the base of the skull where the spinal cord exits.) The majority of Chiari malformations are either type 1 or type 2. Type 2 is usually associated with spina bifida and usually presents in infancy. We generally do not treat this type in our office. Type 2 usually presents in young adulthood.

Who gets a Chiari Malformation?
Average age of presentation for type 1 is 41 years of age. Slightly more common in females. Average duration of symptoms before accurate diagnosis is roughly 3 years.

What are the Symptoms of a Chiari Malformation?
The most common symptom is pain, especially headache, which is usually posterior. The headache is usually made worse by neck extension or by straining. Hand weakness is sometimes present. Numbness in arms/legs, difficulty with coordination, and difficulty with walking are also common symptoms.

What tests are usually ordered?
An MRI (magnetic resonance imaging) is usually ordered of the cervical spine. Contrast may be used to rule out a mass. A CT (computed axial tomography) may also be ordered to evaluate bony anatomy.

Treatment
Surgery is generally recommended for patients who are having symptoms. The best results are usually obtained when surgery is performed within two years of the onset of symptoms. Patients who have had symptoms which are stable for years may be followed nonoperatively, with surgery considered if symptoms worsen.

What is generally done during surgery?
The most common procedure performed is posterior fossa decompression with or without laminectomy of C1, C2, and/or C3. In laymen’s terms, this would involve removing bone off the back part of the skull and upper neck bones to relieve pressure. Most times, the dura (covering of the nervous tissue that contains spinal fluid) is opened to relieve pressure and then patched. This is usually called a “duroplasty.”

What can I expect after surgery?
Patients with predominant pain complains generally have good improvement after surgery, while weakness is sometimes less responsive to surgery. Most importantly, surgery will halt the progression of the Chiari. As with any surgery, some patients may have residual symptoms.

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