What is Chiari Malformation?

Chiari Malformation is a disorder of the brain affecting at least 1 out of every 1000 people in the world. In the simplest terms, it is a condition where the cerebellum (the bottom part of the brain) squeezes out into the spinal canal. Chiari is almost exclusively diagnosed via MRI of the brain, but other types of scans may detect the disorder as well.

Many people are born with the disorder but have no symptoms until adolescence or adulthood because of growth or progression of the herniation. Others can develop it from trauma or from a lack of spinal fluid. The most severe forms of Chiari Malformation are detected at birth and may result in significant brain damage and disability.

Symptoms of Chiari Malformation:

Chiari Malformation symptoms include headaches that are made worse by coughing, sneezing and straining, neck pain, poor balance, nausea and vomiting, hoarse voice and ringing in the ears. Symptoms vary widely between patients and may change over time.

Diagnosis of Chiari Malformation:

The diagnosis of Chiari Malformation is becoming more common because of the increased use of MRI, but many Chiaris are incidental findings in people without any symptoms and who will never require treatment (so if you have one and no symptoms, don't panic!).

Treatment for Chiari Malformation:

Treatment for Chiari Malformation is varied. Most patients are first treated by a neurologist, with medications being used to reduce headaches or other symptoms. Many patients are able to be managed without surgery; however, if medication does not work or the cerebellar herniation gets worse, surgery is usually recommended to provide more room for the herniated brain structures.

During the surgery, called a Posterior Fossa Decompression, a piece of the skull near the opening to the spinal canal is removed, a piece of the first and sometimes second vertebrae are removed, and a patch is added to the lining of the brain. Occasionally, neurosurgeons may surgically shrink the cerebellum to further decrease pressure within the brain or try to reposition the brain within the skull.

Outcomes from surgery vary widely depending upon the patient, the severity of the herniation and the damage done before surgery. 

Chiari Malformation and Associated Conditions:

Syringomyelia is a condition where a backup of spinal fluid causes a cyst to grow in the middle of the spinal cord, which can cause a variety of symptoms including weakness, paralysis, and pain the arms and legs.

Spina Bifida is a condition where the spinal cord doesn't fully close during fetal development.

Many patients with Chiari have a less severe version of Spina Bifida called Occult Tethered Cord, where the bottom part of the spinal cord is tethered to the bones in the lower back, causing a stretch on the spinal cord. Research is being done to determine if Occult Tethered Cord may be an additional cause of the brain hernation in Chiari Malformation.

Pseudotumor Cerebri is a condition where the pressure in the brain is too high, often because the fluid cannot escape from the brain. It is seen often in patients with Chiari Malformation and Syringomyelia.

Ehlers Danlos Syndrome is a connective tissue disorder which can cause joint and tissue looseness, which can be a big problem in the spine, especially after decompression surgery.


National Institute of Neurological Disorders and Stroke - Promotes and supports research for nuerological disorders and strokes

Conquer Chiari - Education, awareness and research into Chiari Malformations

American Syringomyelia and Chiari Alliance Project - Non-profit organization dedicated to research and support

Chiari and Syringomyelia Foundation - Non-profic group committed to finding a cure for Chiari malformations, syringomyelia and other cerebrospinal fluid disorders