LIMITED BENEFIT OF ELECTROPHYSIOLOGICAL STUDIES DURING DORSAL RHIZOTOMY

Using a formula for standard deviation and several assumptions, the po tential benefit of electrophysiological recording (ER) during dorsal r hizotomy for cerebral palsy is calculated and expressed in a ratio, th e electrophysiological recording benefit ratio (ERBR). ERBR is approxi mately 1.1 in most of the examples, but other factors may reduce this ratio. Severing an additional rootlet appears to be a viable alternati ve to ER in most of the examples. Advantages of dorsal rhizotomy witho ut ER include reduced expense and operative time. Prospective studies are recommended to evaluate further the benefit of ER during dorsal rh izotomy. If stimulation of dorsal rootlets is abandoned during dorsal rhizotomy, stimulation of whole dorsal and ventral roofs may still be necessary to prevent inadvertent severing of motor fibers. (C) 1994 Jo hn Wiley and Sons, Inc.