Arnold Chiari Decompression

What Is It?

A Chiari decompression, also called a posterior fossa decompression, suboccipital craniectomy or foramen magnum decompression, is a surgical procedure performed by a neurosurgeon to treat the symptoms of Arnold Chiari malformation, particularly for Type I malformations. Symptomatic patients with Type I Chiari Malformation are often offered this treatment option.

What Does the Procedure Entail?

The primary problem in symptomatic Chiari malformation is crowding of the foramen magnum, the large opening at the base of the skull through which the spinal cord passes, by the descended cerebellar tonsils. To reduce this crowding and allow more room for the structures in this area as well as to improve flow of cerebrospinal fluid through the area, a Chiari decompression aims to create space at the level of the foramen magnum.

The procedure generally involves a linear incision at the back of the head and upper neck. A small part of the skull posterior to the foramen magnum is removed to effectively enlarge the opening, giving more room to the structures within. In many cases the posterior arch of the first cervical vertebrae is also opened to widen this space.

In most cases the dura, the leathery covering of the brain and spinal cord, is also opened in this area and expanded to improve the space within. This expansion, called a duraplasty, can be accomplished either with synthetic dura substitutes or sometimes with a piece of periosteum (the covering of the bone from the skull) from the patient.

Finally, in some cases in which the cerebellar tonsils are large, the tonsils may be removed or reduced in size to make further room for the other nervous system structures in the area.

The specifics of each case and the specific techniques used vary. Each patient should discuss their treatment options with their own treating physicians.

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Important Note: This site is not intended to offer medical advice. Every patient is different, and only your personal physician can help to counsel you about what is best for your situation. What we offer is general reference information about various disorders and treatments for your education.

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