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.
Atlantoaxial instability with and without basilar invagination poses a considerable challenge in management regarding reduction, surgical approach, decompression, instrumentation choice, and extent of fusion. A variety of strategies have been described to reduce and stabilize cranial settling with basilar invagination. Modern instrumentation options included:
Extension to the occiput, C1-C2 transarticular fixation, and C1 lateral mass-C2 pars among others. Since not all cases of cranial settling are the same, their treatment strategies also differ. Factors such as local vascular anatomy, amount of subluxation, need for distraction, and shape of occipital condyles will dictate level and type of instrumentation.
Joint-distraction and intra-operative manipulation surgeries to correct basilar invagination (BI) and atlantoaxial dislocation (AAD) are becoming standard procedures.
Sagittal joint inclination and craniocervical tilt significantly correlated with both BI and AAD (P < .01). Coronal joint inclination correlated with BI (P = .2). The mean sagittal joint inclination value in control subjects was 87.15 ± 5.65° and in patients with BI and AAD was 127.1 ± 22.05°. The mean craniocervical tilt value in controls was 60.2 ± 9.2° and in patients with BI and AAD was 84.0 ± 15.1°. The mean coronal joint inclination value in control subjects was 110.3 ± 4.23° and in patients with BI and AAD was 121.15 ± 14.6°.
It is a important role of joint orientation and its correlation with the severity of BI and AAD and has described new joint indexes 1).
The Transoral atlantoaxial reduction plate (TARP) operation is effective and safe for treating patients with basilar invagination (BI) with Klippel Feil syndrome (KFS). The midterm clinical results were satisfactory 2).