Microsurgery of Arnold-Chiari malformation in adults with and without hydromyelia

Abstract

Microsurgical exploration of 15 adults with Arnold-Chiari malformation with and without hydromyelia was performed using 3-20 times magnification. Hydromyelia, associated with Arnold-Chiari malformation, is a progressive mechanical disorder that causes spinal cord deficits by pressure distention of the cord. Arnold-Chiari malformation causes slowly or suddenly progressive bulbar dysfunction by impaction of the malformation in the foramen magnum. Decompression of both can be achieved by a suboccipital craniectomy, upper cervical laminectomy, establishing an outlet from the 4th ventricle and opening the distended cord in the thinnest exposed area, which is usually along the dorsal root entry zone. If Pantopaque myelography in patients in the supine position showed the Arnold-Chiari malformation, hydromyelia could be established as a cause of central cord deficit even if myelography showed the cord size to be normal. Syringomyelia, traditionally considered a degenerative disease, was a less common cause of a slowly progressive central cord deficit than either hydromyelia or intramedullary tumor.