Extended extradural spinal arachnoid cyst: an unusual cause of progressivespastic paraparesis

A 15-year old girl presented with a slowly progressive spastic paraparesis since the age of 12. Creatine kinase was slighty increased. Muscle biopsy c arried out during tendon surgery for severe toe-walking showed 'myopathic' changes. Subsequent neurological evaluation and radiological studies reveal ed a large extradural arachnoid cyst extending from the 11th thoracic verte bra to the first lumbar vertebra. Her condition improved after operation. T he 'myopathic' features turned out to be the result of chronic spinal compr ession. MRI is the method of choice to examine patients with non-hereditary progressive spastic paraparesis. Muscle biopsy and tendon surgery should n ot be performed, without careful neurological examination. (C) 1999 Elsevie r Science B.V. All rights reserved.