Basilar Invagination is a relatively rare condition in which the upper portion of the second cervical vertebra migrates upward and posteriorly into the intracranial space. It can be associated with a number of other conditions such as rheumatoid arthritis, Chiari malformation, syringomyelia, C1-2 instability, or congenital abnormalities.

Symptoms: Patients generally become symptomatic when the displaced vertebral segment causes sufficient pressure on the upper spinal cord or lower portion of the brainstem. The most common symptoms include headache, dizziness, swallowing problems, numbness/tingling in the extremities, and paralysis. Symptoms can become worse with flexion of the head, which even further drapes the spinal cord over the upper portion of C2.

Diagnosis: This condition is diagnosed by various imaging modalities such as plain x-rays, CT scans, and MRI.

Treatment: Patients with minimal symptoms can be treated with non-operative modalities such as physical therapy, non-steriodal anti-inflammatory medication, or a cervical collar. Surgical treatment is reserved for patients with symptoms refractory to non-operative management, neurological deficit, or severe spinal cord compression. Surgery usually involves the removal of bone that is causing the compression and stabilization using spinal instrumentation.