Occipitocervical Osteotomies and Interfacet Grafts for Reduction of Occipitocervical Kyphosis and Basilar Invagination

Background: Occipitocervical congenital pathologies involving instability of the atlantoaxial joint and basilar invagination are challenging to treat owing to the complex anatomy involving neurovascular structures at the skull base and the high-risk nature of surgery close to the brainstem. Case Description: A patient presented with Alagille syndrome with multiple segmentation/fusion anomalies of the cervical spine and craniocervical junction, including fusion of the skull base and occipital condyles and partial assimilation of the C1 anterior ring and C2 dens. The head was anteriorly displaced, with C2 located immediately below the foramen magnum. There was significant kyphotic angulation due to nonunion of the base of the dens and the body of C2. The patient underwent occipitocervical osteotomies and occiput-C2 interfacet grafts for reduction of occipitocervical kyphosis along with foramen magnum decompression and occiput-C6 fusion. The patient had significant neurologic improvement and sustained improved craniocervical alignment on last follow-up. Conclusions: In patients with atlantoaxial instability with basilar invagination, posterior facet release, local distraction, and placement of cortical bone interbody grafts with occipitocervical fusion may be instrumental in reducing craniocervical kyphosis and compression by allowing anterior translation of the upper cervical spine relative to the skull. This method may be a safe and effective posterior-only approach for brainstem/spinal cord decompression for patients with complex craniocervical congenital malformations.