Intra-operative monitoring in scoliosis surgery with multi-pulse cortical stimuli and desflurane anesthesia.

Abstract

Prospective, observational study. Country General Hospital, Singapore. Intraoperative monitoring (IOM) with motor-evoked potentials (MEPs) assesses the integrity of cortical spinal tracts during scoliosis surgery. MEPs are sensitive to the effects of inhalational anesthetic agents. We evaluate the use of desflurane in combination with multipulse cortical stimulation in this study. In all, 10 consecutive neurologically normal subjects underwent scoliosis surgery with desflurane anesthesia (0.5 maximum alveolar concentration) and five pulse cortical stimulation (250 Hz) from two stimulators in parallel configuration, delivering a maximum intensity of 160 mA. Consistent MEPs were obtained from the abductor hallucis and tibialis anterior in nine of ten and five of five of subjects, respectively. Baseline coefficients of variations were below 16% for both muscles. This combination of anesthetic and stimulation protocols is efficacious for IOM during spinal cord surgery. Our findings support the use of desflurane for successful acquisition of MEPs during scoliois surgery as an alternative anesthetic regime.