Chiari Malformation

Chiari malformation is a rare abnormality. It directly affects the cerebellum, a part of the brain that lies at the base of the skull, behind the brainstem, which leads to the spinal cord. The cerebellum coordinates the body's movement.  In this condition, the lower part of the cerebellum sticks down into the spinal canal. This causes pressure on the tissues and keeps the spinal fluid from flowing normally.


Chiari malformation may or may not be seen at birth. The condition is associated with hydrocephalus, in which case it will be apparent at birth.

The symptoms may begin to appear as the person grows older. They may include headache at the back of the head that grows worse with coughing or straining, dizziness, double vision, unusual eye movements, pain or numbness in the face, arms or legs or ringing in the ears.

Causes and Risk Factors

The exact cause is not known. It may happen in the early stages of the development of the brainstem and spinal cord. The brainstem is a stalk-like part of the brain that connects the main portion of the brain to the spinal cord.

If the back portion of the skull is abnormally small, the brainstem or tonsils may be pushed down through the opening at the bottom of the skull.

Although a form of this occurs in children, the Chiari I malformation usually causes problems in adults. The Chiari I malformation occurs slightly more often in women than in men.


The treatment of a Chiari I malformation is a surgery to relieve the pressure on the area. This procedure enlarges the back of the head.