ABSTRACT
Multi-modal neurophysiologic monitoring consisting of triggered and spontaneous electromyography and transcranial motor-evoked potentials may detect and prevent both acute and slow developing mechanical and vascular nerve injuries in lateral lumbar interbody fusion (LLIF) surgery. In case report 1, a marked reduction in the transcranial motor-evoked potentials on the operative side alerted to a 28% decrease in mean arterial blood pressure in a 54-year-old woman during an L3-4, L4-5 LLIF. After hemodynamic stability was regained, transcranial motor-evoked potentials returned to baseline and the patient suffered no postoperative complications. In case report 2, a peroneal nerve train-of-four stimulation threshold of 95 mA portended the potential for a triggered electromyography false negative in a 70-year-old woman with type 2 diabetes, peripheral neuropathy, and body mass index of 30.7 kg/m undergoing an L3-4, L4-5 LLIF. Higher triggered electromyography threshold values were applied to this patient's relatively quiescent triggered electromyography and the patient suffered no postoperative complications. In case report 3, the loss of right quadriceps motor-evoked potentials detected a retractor related nerve injury in a 59-year-old man undergoing an L4-5 LLIF. The surgery was aborted, but the patient suffered persistent postoperative right leg paresthesia and weakness. These reports highlight the sensitivity of peripheral nerve elements to ischemia (particularly in the presence of vascular risk factors) during the LLIF procedure and the need for dynamic multi-modal intraoperative monitoring.
