P07.02 * THE ROLE OF INTRAOPERATIVE NEUROPHYSIOLOGICAL MONITORING IN SURGERY OF INTRADURAL EXTRAMEDULLARY SPINAL CORD TUMORS

Abstract

INTRODUCTION: Surgery of intradural extramedullary spinal cord tumors (IESCT) carries the risk of new neurological deficits in the post-operative period. Intraoperative neurophysiological monitoring (IONM) represents the most effective technique able to improve clinical and functional outcomes, which are obtained through identification and real-time intraoperative monitoring of spinal cord, giving informations about neurological conduction of both, spinal cord long pathways and cauda equina radices. The most widely used and reliable techniques are somatosensory evoked potentials (SEPs), motor evoked potentials (MEPs) and D-wave registration. Although in the literature there are recent evidences of the IONM usefulness, there are not uniform opinions about the different techniques employed, and, their use in IESCT. In the present study we describe the results in our 2-year experience at the Neurosurgery of the University of Messina Hospital. MATERIALS AND METHODS: Our protocol includes evaluation of SEPs from posterior tibial nerve stimulation, MEPs obtained with elevate voltage electrical transcranial stimulation (through multiple myomeric registration of motor evoked responses from inferior limbs), D-Wave registration (through epi- and intradural registration after single pulse electrical transcranial stimulation) in spinal tumor surgery. RESULTS: We did not recorded any intraoperative complication by the use of our IONM protocol. In all patients IONM was useful for correct neurological and functional identification of spinal cord. We observed an optimal correlation between neurological examination on admission and responses from IONM of inferior limbs SEPs and MEPs. In fifty percent of patients, the D-wave registration was the most useful intraoperative tool, due to the lack of motor and somatosensory evoked responses. We matched all pre and post-operative neurological and neurophysiological data, along with tumors' features (localization, dimensions and histology) in order to quantify the impact of IONM on outcome. In our series, none of the patients presented with neurological worsening in the post-operative period. Conversely, surgical treatment of IESCT lead to a significant improvement of neurological status of our patients. CONCLUSIONS: Our preliminary data, although based on a limited series of patients evaluated at a single institution, confirm the role of IONM as an essential tool in operative work-up of all spine surgeries, including IESCT, to achieve an optimal post-operative functional outcome. This study gives further evidences about relevance, impact and usefulness of IONM in IESCT surgery.