P-IM003. The utility of intraoperative Neurophysiological monitoring in surgical correction for spinal arteriovenous shunts: A historical control study

Abstract

Introduction . This study aimed to investigate the utility of intraoperative neurophysiological monitoring (IONM) in surgical correction for spinal arteriovenous shunts (SAVSs). Methods . We retrospectively reviewed 42 patients underwent surgical correction for SAVSs. 29 patients who underwent multimodal IONM (transcranial electrical motor-evoked potentials [tcMEP], somatosensory-evoked potentials [SSEP], continuous electromyography, and bulbocavernosus reflex [BCR]) from 2011 to 2020 were compared to 13 historical controls (non-IONM groups) from 2003 to 2009. The rates of postoperative neurological deficits, neurophysiological warnings, and their characteristics were analyzed. Postoperative neurological deficits were evaluated at one month, six months, and one year after surgery, respectively. Results . Among 42 patients, postoperative neurological deficit rates were 13.8% and 46.2% in the IONM and non-IONM groups, respectively (p = 0.046). In total, 5 warnings were observed during IONM (3 tcMEP; 1 tcMEP and SSEP; 1 BCR). Three cases were true-positive. The amplitude of right abductor halluces MEP decreased during surgery in patient 1 who had no weakness of the right leg previously. After surgery, weakness of right leg was newly observed in patient 1. Patient 2 who had both leg weakness previously got worse both leg weakness than before surgery. Her left abductor halluces MEP disappeared and never recovered during surgery. Patient 3 had normal bladder function before surgery. His baseline BCR was successfully recorded but the end of the surgery, the bilateral BCR was completely disappeared. He had severe urinary retention after surgery. Sensitivity, specificity, positive predictive value, and negative predictive value of IONM warnings for detecting postoperative neurological complications were 75.0%, 92.0%, 60.0%, and 95.8% respectively. Conclusion . The utility of IONM in surgical correction for SAVSs has not been evaluated due to its rarity. This is the first study to provide results revealing that IONM helps to improve postoperative neurological outcome through comparison with non-IONM group in surgical correction for SAVSs.