Circumferential Thoracic Cord Compression Due to Combined Ossified Yellow Ligament and Ossified Posterior Longitudinal Ligament Managed by a Posterior-Only Approach.

Thoracic myelopathy caused by combined ossified yellow ligament (OYL) and ossified posterior longitudinal ligament (OPLL) is exceptionally rare and presents unique diagnostic and surgical challenges. We report a 45-year-old female with rapidly progressive gait disturbance and severe myelopathy found to have circumferential spinal cord compression at T3-T4 due to simultaneous dorsal OYL and ventral OPLL. MRI and CT imaging were essential in defining the extent of compression and ossification. Considering the morbidity of anterior thoracic exposure, a tailored posterior-only approach incorporating laminectomy, OYL excision, costotransversectomy-assisted partial OPLL decompression, and instrumented stabilization was performed, achieving adequate circumferential release. The patient demonstrated meaningful neurological recovery, improving from Nurick Grade 5 to Grade 3 within three months. This case highlights the importance of early recognition, comprehensive imaging, and individualized posterior-based strategies in managing complex upper thoracic stenosis caused by dual ossified pathologies.