Intramedullary arachnoid cyst: 3-year follow up after bilateral dorsal root entry zone myelotomy.

Spinal arachnoid cysts are relatively uncommon an intramedullary location is believed to be extremely rare. A 35 year old woman, admitted with progressive weakness in the lower limbs, was diagnosed as having a thoracic intramedullary arachnoid cyst. After bilateral dorsal root entry zone myelotomy procedures and wide fenestration was performed, there was a dramatic and immediate recovery. This is the first intramedullary arachnoid cyst reported to be treated by this approach and the long term outcome discussed.