Neuromyelitis Optica Spectrum Disorders (NMOSDs) Diagnosed After Surgery for the Ossification of the Posterior Longitudinal Ligament of the Cervical and Thoracic Spine: A Case Report.

Complications of compressive spinal cord myelopathy and demyelinating disease can be difficult to diagnose. A 65-year-old woman gradually lost the ability to walk. Her imaging findings showed multiple spinal canal stenosis and ossification of the posterior longitudinal ligament in the cervical and thoracic spine. Some intramedullary signal changes were seen at sites distant from the spinal cord compression site. Although she underwent cervical and thoracic decompression and fusion surgery relatively early, her lower-extremity strength decreased after surgery. Her aquaporin 4 (AQP4)-antibody was found to be positive postoperatively, and she was diagnosed with NMOSD. Medical treatment for NMOSD improved her walking ability, and she finally became able to walk with a cane. In cases where there is a discrepancy between the site of strong stenosis and intramedullary signal changes, it is necessary to consider an anti-AQP4 antibody test and consultation with a neurologist.