Complex Chiari Malformation Presenting with Bulbar Symptoms in an Adult: Single-stage Posterior Fusion and Foramen Magnum Decompression: A Rare Case Report

Complex Chiari malformation (CCM) is a spectrum of congenital bony and soft tissue abnormalities, which includes Chiari 1.5 malformation, medullary kinking, retroflexed odontoid, abnormal clival-cervical angle (CXA), occipitalization of the atlas, basilar invagination, syringomyelia, and scoliosis. CCM usually manifests in the pediatric age group and is a challenging entity to treat. It requires detailed evaluation of craniometric indices to decide the appropriate surgical management. Patients with maximum perpendicular distance of dens to the line from the basion to the inferoposterior part of the C2 body (pBC2 line) of more than 9 mm and CXA <125° require a posterior fixation and will benefit from a single-stage posterior fusion and foramen magnum decompression (FMD). We report a rare case of CCM manifesting in a 32-year-old male with brainstem compression and bulbar symptoms. We could realign the craniovertebral junction with only a C1-C2 fixation by a modified distraction, compression, extension, and reduction technique and also relieve the neural compression by FMD and tonsillar resection in a single surgery with a good outcome. The authors find it to be an effective alternative to avoid the occipital fixation.