Chiari Malformation: Definition, Causes, Symptoms, and Treatment

Cerebellum

Model of the human brain: the cerebellum is in purple

A Chiari malformation (CM) is a structural defect in the cerebellum, the round portion of the brain at the base of the back of the skull. The cerebellum controls balance, among other things, and normally rests in an indented space above an opening to the spinal canal.

In a Chiari malformation, part of the cerebellum is located below this opening. A CM may occur when the bony space is smaller than normal, which causes the cerebellum and brainstem to be pushed down through the opening and into the upper spinal canal.

This puts pressure on the cerebellum and brainstem, which may affect a person's functions that are controlled by these areas of the brain.

A Chiari malformation may be caused by a structural defect in the brain and spinal cord arising during the development of the fetus. This can result from a genetic mutation or a lack of nutrition in the mother's diet.

Symptoms of a Chiari malformation depend on the type of CM a person has. Some people with a Chiari malformation may have neck pain, balance problems, muscle weakness, numbness or other unusual feelings in the arms or legs, or dizziness. Other symptoms can include vision problems, difficulty swallowing, ringing or buzzing in the ears, hearing loss, vomiting, insomnia, depression, or headache.

People who have a Chiari malformation often have another related condition, such as hydrocephalus (an excessive buildup of cerebrospinal fluid in the brain); spina bifida (the incomplete development of the spinal cord and/or its protective covering); and spinal curvature.

Treatment for Chiari malformations is limited: if a person has functional disturbances or progressive damage to the central nervous system, surgery must be performed to correct the disturbances or prevent the damage from worsening.

For more information, see this fact sheet from the U.S. National Institutes of Health, and...
this article for links to medical sources for more information.