What is a Chiari Malformation?

A Chiari Malformation is a congenital malformation which causes defects in the cerebellum, the part of the brain which is responsible for balance, muscle control, and sensory perception. There are four grades of Chiari Malformation, with Type I being the most mild, and Type IV the most severe. Several treatment tools can be used to treat and manage a Chiari Malformation, which may allow the patient to live a relatively normal life, depending on the severity of the malformation.

This malformation was first described in the 1800s by Hans Chiari. Another physician, Julius Arnold, also contributed to the body of knowledge about this birth defect, leading some people to refer to this condition as an Arnold-Chiari Malformation, in a desire to recognize both of the major early researchers. It is caused by a change in the shape of the skull which pushes down on the cerebellum, forcing the cerebellum and brain stem into the spinal canal and restricting the flow of cerebrospinal fluid.

Patients with a Type I Chiari Malformation may manifest such mild symptoms that they don't even realize they are afflicted. Type II and III patients have much more severe forms, which typically require treatment, while Type IV patients can have incompletely formed or developed brains, leading to very serious consequences. In all cases, a scan of the head can usually reveal the classic signs of a Chiari Malformation, with the distorted shape of the brain being clearly visible on an imaging study.

Chiari Malformations can cause a variety of symptoms, including balance, muscle control, and vision problems. Some patients also suffer from headaches, random stabbing pains, muscle weakness, dizziness, neck pain, difficulty swallowing, hearing problems, slurred speech, abnormal breathing, and spinal problems. Patients may also be prone to falls. If untreated, a patient may develop paralysis or a buildup of fluid on the brain which could be extremely dangerous.

Specific medications can be used to help manage the pain associated with a Chiari Malformation. In addition, surgical treatment can be used to relieve the pressure on the cerebellum; typically several vertebrae or part of the skull can be removed to make room for the brain. Surgical treatment can also be used to address concerns about impaired brain and nervous system function caused by restricted circulation of cerebrospinal fluid. In patients who develop hydrocephalus, a shunt may be installed to drain the excess fluid.