Traumatic spinal extradural arachnoid cyst—A case report

Spinal extradural arachnoid cysts (SEACs) can be congenital or acquired and are assumed to result from dural defects. Communication between the cysts and the intradural subarachnoid space is reported in nearly all cases of SEACs. The mainstay of the current treatment is resection of the cyst wall followed by obliteration of the communicating hole. Despite its clinical importance, the location of the dural defect is often elusive before operation. We report a case of a patient presenting with an extradural arachnoid cyst as a sequel of a major blunt trauma of the lower back approximately 20 years ago. The 56-year-old man presented with progressive paraparesis and back pain. Radiographic images of the lumbar spine showed scalloping of the L1–2 vertebrae. Magnetic resonance imaging of the spine revealed an SEAC at the T10–L2 levels. During the operation, an ovoid dural defect was identified at the L1 level, which coincided with the area where the most severe vertebral scalloping was observed. We postulate that delayed-onset posttraumatic extradural arachnoid cysts should be considered during the differential diagnosis of intraspinal cysts, and vertebral scalloping can be used as a sign to locate dural defect before surgery. Keywords: Extradural arachnoid cyst, Myelopathy, Trauma, Vertebral scallopin