Thoracic Disc Herniation of the Adjacent Segment With Acutely Progressing Myelopathy

We report a case of a 66-year-old woman with progressing myelopathy. Her history revealed instrumented fusion from T10 to S1 for degenerative lumbar kyphosis and spinal stenosis. The plain radiographs showed narrowing of the intervertebral disc space with a gas shadow and sclerotic end-plate changes at T9-T10. Magnetic resonance imaging revealed a posterolateral mass compressing the spinal cord at the T9-T10 level. The patient was treated with a discectomy through the posterior approach combined with posterior instrumentation. The patient's symptoms and myelopathy resolved completely after the discectomy and instrumented fusion. The thoracic disc herniation might have been caused by the increased motion and stress concentration at the adjacent segment.