H-REFLEX STUDIES IN CEREBRAL-PALSY PATIENTS UNDERGOING PARTIAL DORSALRHIZOTOMY

H reflex studies were performed in ten spastic children with cerebral palsy who underwent partial dorsal rhizotomy (PDR). Under anesthesia p rior to PDR, H reflex amplitude evoked by percutaneous peripheral nerv e stimulation gradually declined in all patients and became unobtainab le in five. Motor responses could still be evoked by apparent dorsal r oot stimulation in these five, but since it was shown that they were M responses and not reflexes, PDR was performed randomly. In the other five patients, in whom H reflexes were still evokable, dorsal root sti mulation evoked motor responses which were true reflex responses, and PDR was performed ''selectively.'' Compared to preoperative values, po stoperative H-max/M(max) ratios declined, but no more so in selective than in random PDR. We conclude that current intraoperative methods fo r selection of ''abnormal'' dorsal rootlets for section may be invalid and may have no bearing on successful outcome, since spasticity impro ves even with random PDR. (C) 1994 John Wiley and Sons, Inc.