Dorsal spinal cord herniation at the thoracolumbar junction presenting with scalloping of ossification of the ligamentum flavum: case report.

Dorsal spinal cord herniation is reportedly a rare condition. Here, the authors report an unusual case of dorsal spinal cord herniation at the thoracolumbar junction presenting with scalloping of ossification of the ligamentum flavum (OLF). A 75-year-old woman with a 2-year history of bilateral leg dysesthesia presented with progressive gait ataxia. Neurological examination showed bilateral patellar tendon hyperreflexia with loss of vibratory sensation and proprioception in her bilateral lower extremities. CT myelography revealed a posterior kink and dorsal herniation of the spinal cord at T11-12, with OLF between T10-11 and T12-L1. In addition, scalloping of the OLF was observed at T11-12 at the site of the herniated spinal cord. This scalloping was first noted 9 years previously and had been gradually progressing. The patient underwent surgical repair of the spinal cord herniation. Subsequently, her spinal cord herniation and vibratory sensation and proprioception in both legs partly improved, but gait ataxia remained unchanged. Dorsal spinal cord herniation reportedly occurs under conditions of vulnerability of the dorsal dura mater. In this case, acquired vulnerability of the dorsal dura mater owing to previous epidural catheter placement into the thoracolumbar space may have resulted in dorsal spinal cord herniation.