Multimodality neurophysiological monitoring during tibial/fibular osteotomies for preventing peripheral nerve injuries.

Previously, intraoperative neurophysiological monitoring was not used routinely during tibial osteotomies. In an attempt to improve the post-operative outcomes and reduce known neurologic complications, we used discrete multimodality recording and stimulation models to identify areas of motor and sensory function in eighteen (18) pediatric patients presenting with Tibia Vara (Blount's Disease). By using both posterior tibial and peroneal nerves somatosensory evoked potentials (SSEPs) with transcranial electrical motor evoked potentials (TCeMEPs) precise status of sensory and motor pathways was possible during surgical correction. Similarly, spontaneous electromyography (s-EMG) and triggered electromyography (t-EMG) were used to more accurately localize nerve irritation. Concerns during tibial and fibular osteotomies included ipsilateral lower limb motor and sensory function, especially peroneal nerve injuries due to the location of the osteotomy at the fibular neck. Surgical interventions consisting of additional fibular resection were made during the index procedures for four patients because of real-time monitoring changes noted as the peroneal nerve was entrapped in three patients at the osteotomy site. In fourth patient, the tourniquet pressure was the cause for loss of ipsilateral SSEPs and TCeMEPs. After appropriate surgical intervention, monitoring parameters began to normalize and postoperatively the patients presented with no neurologic deficit. In this study, the application of multimodality recording and stimulation models were utilized including posterior tibial nerve and peroneal nerve SSEP with lumbar potential (LP) identification to compare with contralateral limb recordings. In addition, by using spontaneous and triggered EMG and TCeMEP, we were able to perform monitoring with a high level of confidence throughout surgery.