Thoracic radiculopathy caused by ossification of the ligamentum flavum

Thoracic ossification of the ligamentum flavum (OLF) has been widely recognized as a main cause of thoracic myelopathy in Asia, particularly in Japan. However, thoracic OLF rarely causes radiculopathy. We report a rare case of thoracic radiculopathy caused by OLF. A 67-year-old male presented with a chief complaint of back pain radiating to the right of the abdomen. Neurological examination revealed mild sensory deficit at the right side of the abdomen at the T9–10 level. Magnetic resonance imaging and computed tomography demonstrated OLF at the right T9–10 level. Thoracic radiculopathy caused by OLF was suspected. Because conservative treatment was not effective to this lesion, surgical intervention was performed, and the pain disappeared immediately after the operation. Thoracic OLF rarely causes radiculopathy, but it should be considered as a differential diagnosis of thoracic radicular pain. When conservative treatment is not effective in this lesion, surgical treatment should be considered.