In children with spasticity, deep tendon reflexes are hyperactive and even stimulation of normal dorsal rootlets can produce exaggerated full-strength, single-twitch responses in the muscles they innervate. This phenomenon is called the brisk hyperactive response (BHR). The aim of this study was to compare the efficacy of 2 volatile anesthetics, isoflurane and sevoflurane, for suppressing the confounding effect of BHR during selective dorsal rhizotomy (SDR) in children with spasticity. The subjects were 54 consecutive children of American Society of Anesthesiology physical status III who were scheduled for SDR. After tracheal intubation, each child was randomly assigned to Group I (isoflurane; n = 27) or Group S (sevoflurane; n = 27). There was no significant difference between the mean operation times in Groups I and S (200 +/- 40 vs. 220 +/- 35 minutes, respectively; p = 0.0559). Thirteen patients in Group I (48.1%) and 5 in Group S (18.5%) exhibited BHR during stimulation of the dorsal rootlets (odds ratio 4.086; p = 0.0418). Three of these 18 patients (2 in Group I and 1 in Group S) experienced hypertension and tachycardia simultaneously with BHR (odds ratio 4.086; p = 1.0). The results suggest that sevoflurane is more effective at preventing BHR and might be a better choice for anesthetic management of children with spasticity undergoing SDR. (C) 2008 Elsevier Ltd. All rights reserved.