T139. The utility of Intraoperative Neurophysiologic Monitoring (IONM) in latarjet procedures

Introduction The Latarjet procedure is a surgical treatment option in treatment of shoulder instability and can be associated with up to 10% risk of a new postoperative neurologic injury. The utility of IONM during the Latarjet procedure is previously demonstrated in one study that assessed the relative risks of distinct surgical steps ( Delaney, 2014 ). However, the spectrum of neurophysiologic changes remains undefined. In this study, we reviewed the pattern of changes, sensitivity and specificity of IONM in detection of a new postoperative neurologic deficit. Methods A retrospective chart review was performed in our prospectively collected database to identify patients undergoing Latarjet procedure with utilization of IONM. A total of 14 Latarjet procedures was performed in 12 patients with a median age of 37, between August 2013 and April 2017. We reviewed demographic information, intraoperative details including neurophysiologic monitoring and clinical follow up data postoperatively at 2 weeks and 6 weeks. Results Out of the 14 latarjet procedures, neurophysiologic changes were encountered in 6 procedures and included changes only in the transcranial motor evoked potentials (tcMEPs). There were no changes in somatosensory evoked potentials (SSEP) after ipsilateral median or ulnar nerve stimulation. The tcMEP changes were persistent in 4 procedures and transient in the remaining two procedures. No patient without an intraoperative alert or a transient tcMEP change experienced a new postoperative deficit. Out of the four patients with persistent tcMEP changes, three patients experienced new sensory and motor postoperative deficits in the axillary nerve distribution at 2-week follow-up. One patient continued to experience persistent motor and sensory deficits at 6 week follow up and the remaining two patients demonstrated significant clinical improvement with only residual sensory symptoms. The IONM overall demonstrated 100% sensitivity and 90.9% specificity for a persistent tcMEP change in detecting a new postoperative neurologic deficit. Conclusion This review demonstrates the utility of tcMEPs in predicting intraoperative axillary nerve injury and related postoperative neurologic deficits. Sampling of the deltoid muscle in anterior, middle and posterior compartments increased the sensitivity for detection of an axillary nerve injury. This review also highlights a need for revision of the SSEP monitoring protocol as the postoperative neurologic deficits in the axillary nerve were not detected with median or ulnar nerve stimulation.