Can increased stimulus intensity improve Anesthetic Fade and detect spinal cord injury in intraoperative cerebral spinal cord monitoring?

Abstract

Muscle evoked potential after electrical stimulation to the brain [Br(E)-MsEP] requires measures to reduce the drug-induced decrease in amplitude: Anesthetic Fade. In this observational study, we examined the effect of increasing stimulus intensity on amplitude values. In 528 spinal surgeries, 120 cases showed some waveform reductions. In the 120 cases, amplitude recoveries were observed in 65 cases (54.2%) by increasing stimulus intensity, and 9 cases (7.5%) showed the recovery by addition of double-train stimulation. In the 46 patients who failed to recover amplitude by increasing stimulus intensity, 28 patients recovered that after anesthetic and/or surgical interventions. 102 patients (85%) with amplitude recoveries had good neural prognosis. Postoperative neuropathy occurred in 11 (61%) out of 18 patients who showed reductions of less than 30% of baseline amplitude value in the final waveform. In the cases of the patients who Anesthetic fade was suspected, there was a tendency for amplitude recovery to be seen by increasing stimulus intensity.