Spinal intradural arachnoid cyst associated with diastematomyelia in an adult: a case report and review of literature.

We report a case of a spinal intradural arachnoid cyst in a thirty year old female with a previously undiagnosed and untreated diastematomyelia. The cyst was located exactly between the two hemi-cords of the split cord malformation. The patient was treated successfully by laminoplasty and total removal of the cyst. Additionally, sectioning of the filium terminale was done in the same sitting by a separate incision. This case posed a diagnostic dilemma. Though the clinical findings favoured an extramedullary lesion, the possibility of cystic degeneration in the spinal cord due to the tethered cord syndrome could not be completely negated. Spinal intradural arachnoid cysts have been reported in association with various neural tube defects, mainly in the paediatric age group. However, such a lesion associated with diastematomyelia in an adult, to the best of our knowledge, has not been reported previously.