Chiari Malformation
Chiari malformation is a structural abnormality in which brain tissue extends into the spinal canal and compresses structures in this region. The lower part of the cerebellum, known as the cerebellar tonsils, which are normally completely within the skull, protrude into the upper spinal canal.
Chiari malformation is classified into several types, including:
- Type I: This is the most common type, present at birth but usually not diagnosed until adolescence or adulthood. It often has no symptoms and is discovered incidentally. In Type I Chiari malformation, the cerebellar tonsils protrude into the upper spinal canal, but the rest of the brain structures remain in their normal positions.
- Type II: This type is uncommon, is present at birth and is usually associated with spina bifida. In Type II Chiari malformation, both the cerebellar tonsils and other parts of the brain protrude into the spinal canal.
- Type III and IV: Type III and IV Chiari malformations are severe developmental abnormalities of the brain which are diagnosed in childhood.
The cause of Chiari malformation is not known. It is a congenital condition, meaning it is present at birth, and there may be a genetic cause. In some cases, Chiari malformation is associated with other conditions, such as hydrocephalus or spinal cord syringomyelia (the presence of a fluid-filled cyst in the spinal cord).
Chiari malformation may cause headache, neck pain, dizziness, ringing in the ears, poor balance, numbness or tingling, difficulty swallowing, and muscle weakness. Most people with Chiari malformation have no symptoms and may only be diagnosed incidentally on scans done for other reasons.
Treatment is only required for Chiari malformation definitely causing symptoms. In mild cases, only monitoring is required. When symptoms are more severe, surgery may be recommended. Surgery for Chiari malformation is a “posterior fossa decompression”, where bone is removed from the back of the skull and upper spine to make more space for the affected brain structures and improve fluid flow in the spinal cord and brain.
It is important to work closely with your healthcare team to develop a comprehensive treatment plan that is tailored to your individual needs and goals. The team will be able to provide you with more detailed information about your specific situation and help you understand what to expect.