Multiple extradural spinal arachnoid cysts: a case report and review of the literature.

Extradural spinal arachnoid cysts are rare lesions, which may become symptomatic due to mass effect. Multiple cysts are even rarer of which few are reported to date. A 17-year-old male with acute onset urinary retention and progressive paraparesis is presented. Magnetic resonance imaging of spine revealed multiple spinal extradural arachnoid cysts located dorsal to the spinal cord, causing mass effect. The patient underwent surgery for excision of the cyst and closure of dural defects. He gained urinary continence and near normal muscle strength of lower extremities over a period of two weeks following operation. Up to date, there have been only sixteen reported cases of multiple spinal extradural arachnoid cysts in the literature and the present case appears to be the second most extensive one reported so far. Appreciation of the rarity of such lesions as well as the importance of surgical planning (especially pre-operative localization of the dural defects) is highlighted.