Arnold-Chiari Malformation

A congenital anomaly of the cerebellum and brainstem. Although four types have been identified, type I is the most common type addressed neurosurgically. Type I is characterized by excessive protrusion of the cerebellar (the cerebellum is the balance and coordination center of the brain) tonsils through the foramen magnum (the passageway between the skull and spinal canal where the spinal cord joins the brainstem) down to the first or second level of the cervical spine. With the herniation of the cerebellum, the brainstem and upper spinal cord can be compressed resulting in some potentially serious damage.

This condition may or may not be associated with Syringomyelia (dilated areas within the center of the spinal cord).

Symptoms

The most common symptoms are headache or neck pain – made worse by coughing, sneezing or extension of the head and neck. Other symptoms may include problems with balance or visual motor problems (“distorted vision”).

For those patients who may also develop syringomyelia, altered sensation of the arms and/or legs may be an additional symptom.

Diagnosis

The diagnosis of Arnold-Chiari Malformation (and Syringomyelia) is best made with a MRI scan of the brain and/or cervical spine.

Treatment

The only effective treatment for Arnold-Chiari Malformation is surgery. The operation involves a Suboccipital Craniectomy (surgical opening of the back of the head) to decompress the cerebellar tonsils with a C1 and/or C2 Laminectomy (removal of the roof of the first two cervical vertebrae) to decompress the cervical spinal cord. Another important process is to cut bands of adherent tissue inside the dura mater (the tough leather-like covering of the brain and spinal cord) that surround the spinal cord and the brainstem.

In order to maintain adequate decompression of the brain, brainstem and spinal cord, we sew in a graft as part of the closure of the dura mater.