Basilar invagination


Basilar invagination is invagination of the base of the skull that occurs when the top of the C2 vertebra migrates upward. It can cause narrowing of the foramen magnum. It also may press on the lower brainstem.
This is similar to Chiari malformation. That, however, is usually present at birth.

Symptoms

Symptoms vary depending on whether the spinal cord, brain stem, nerves or their blood supply is affected by the pressure.
Symptoms become apparent when the neck is bent. They include:
Complications from this can include hydrocephalus, pseudotumor cerebri or syringomyelia because it blocks the flow of fluid around the brain and spinal cord.

Causes

Basilar invagination can be present at birth. If the condition develops after birth, it is usually the result of injury or diseases. If due to injury, about half the time it is caused by vehicle or bicycle accidents; 25% of the time by falls and 10% of the time by recreational activities such as diving accidents.
It also occurs in patients with bone diseases, such as osteomalacia, rheumatoid arthritis, Paget's disease, Ehlers-Danlos syndrome, Marfan syndrome, and osteogenesis imperfecta.

Diagnosis

A doctor will base his or her diagnosis on the symptoms the patient has and the results of tests, including:
If there aren't neurological symptoms and there is no evidence of pressure on the spinal cord, a conservative approach may be taken such as:
If there is pressure on the spinal cord or life-threatening symptoms are present, surgery is recommended.