Intraspinal extradural arachnoid cyst with spinal cord herniation

Abstract

A 17-year-old male presented with thoracic myelopathy 12 months after a stab injury to the thoracic spine. The patient reported that symptoms and signs had gradually worsened in the 3 months prior to his examination. Magnetic resonance imaging depicted not only an extradural arachnoid cyst but severe spinal cord compression. The cerebrospinal fluid pressure and dynamics associated with herniation of the spinal cord resulted in the formation and enlargement of an extradural arachnoid cyst. The pressure effect of the cyst accounted for the thoracic myelopathy.