also called: Arnold-Chiari malformation
Chiari malformations (CMs) are structural defects in the base of the skull and the cerebellum, the part of the brain that controls balance. When part of the cerebellum extends through the opening at the base of the skull, the cerebellum and brain stem can be pushed downward. The resulting pressure on the cerebellum can block the flow of cerebrospinal fluid (CSF, the liquid that surrounds and protects the brain and spinal cord) and can cause a range of symptoms including dizziness, muscle weakness, numbness, headache, and problems with hearing, balance, and coordination.
Symptoms may change for some individuals depending on buildup of CSF and any resulting pressure on tissue and nerves. CMs are classified by the severity of the disorder and the parts of the brain that protrude into the spinal canal.
Not all CMs required surgical treatment. When appropriate, a surgical procedure called a Posterior Fossa Decompression provides a solution to this condition. This surgery is performed to create space for the cerebellum, relieve pressure on the spinal cord, and help restore normal flow of CSF.