243. Should somatosensory evoked potentials and motor evoked potentials monitoring be routinely used in all posterior cervical operations for degenerative conditions of the cervical spine?

Abstract

<h3>BACKGROUND CONTEXT</h3> Posterior decompression with or without instrumented fusion (PCF) are some of the most common procedures undertaken by spine surgeon. PCF can be the preferred approach for treating patients with cervical spinal traumatic fractures, degenerative spondylosis, deformity tumors, infection and vascular malformations. Intraoperative monitoring is helpful during cases where direct or indirect manipulation of the cord is expected. However, whether neuromonitoring is necessary in routine PCF surgery for degenerative cervical spine conditions remains unknown. <h3>PURPOSE</h3> Here we evaluate the utility of somatosensory evoked potential (SSEP) and motor evoked potential (MEP) monitoring as a tool for predicting postoperative neurologic deficits during PCF for degenerative cervical spine conditions. <h3>STUDY DESIGN/SETTING</h3> Retrospective review of prospectively collected clinical data. <h3>PATIENT SAMPLE</h3> This study included 498 patients who underwent posterior cervical operations for degenerative conditions of the cervical spine, excluding indications such as tumor, trauma, deformity, vascular lesions, and infection. <h3>OUTCOME MEASURES</h3> Sensory and motor neurologic deficit postoperatively. <h3>METHODS</h3> We retrospectively reviewed cases in which PCF was performed for a variety of cervical spine conditions at our institute over a 5-year period. SSEP monitoring was performed in all patients with MEP monitoring performed in only a subset of patients. Patients who had neurologic deficits postoperatively were then identified and detailed analysis was performed to ascertain whether SSEP or MEP monitoring accurately predicted onset of postoperative deficits. The sensitivity, specificity and predictive value of each monitoring paradigm was then determined. <h3>RESULTS</h3> We retrospectively evaluated clinical outcomes and intraoperative monitoring data in 757 patient and identified 498 patients who underwent posterior cervical operations for degenerative conditions of the cervical spine, excluding indications such as tumor, trauma, deformity, vascular lesions, and infection. Forty percent were female, 60% were male with ages ranging from 22 to 93 years-old (mean 67 years-old). SSEP were monitored for all 498 patients during surgery (121 patients [24.3%] had both MEP and SSEP monitoring). Twenty-one patients (4.2%) had neurological deficits after surgery in this cohort. SSEP monitoring had a higher specificity and sensitivity than MEP monitoring for detecting neurologic compromise intraoperatively in PCF cases (91% vs 79% and 60% vs 20% respectively). The positive (PPV) and negative predictive values (NPV) of SSEP monitoring in picking up intraoperative changes that translated to postoperative neurologic deficit were 30% and 97% respectively whereas PPV and NPV of MEP monitoring were 6% and 96% respectively. <h3>CONCLUSIONS</h3> Taken together, these data suggest that intraoperative SSEP and MEP monitoring during PCF is not reliable at predicting postoperative neurologic deficits. With their relatively high NPV, however, MEP and more so SSEP are useful to provide peace of mind intraoperatively when no abnormalities are detected. Thus, use of SSEP and MEP monitoring in PCF should only be limited to cases where the risk of postoperative neurologic deficit is high. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.