Chiari malformations (CMs) are structural defects in the cerebellum. The cerebellum is the part of the brain that controls balance. With CM, brain tissue extends into the spinal canal. It can happen when part of the skull is too small, which pushes the brain tissue down. There are several types of CM. One type often happens in children who have neural tube defects. Some types cause no symptoms and don't need treatment. If you have symptoms, they may include
Neck pain
Balance problems
Numbness or other abnormal feelings in the arms or legs
Dizziness
Vision problems
Difficulty swallowing
Poor hand coordination
Doctors diagnose CM using imaging tests. Medicines may ease some symptoms, such as pain. Surgery is the only treatment available to correct or stop the progression of nerve damage.
NIH: National Institute of Neurological Disorders and Stroke