Should Somatosensory and Motor Evoked Potential Monitoring Be Used Routinely in All Posterior Cervical Operations for Degenerative Conditions of the Cervical Spine?

Abstract

Intraoperative neuromonitoring (IONM) is useful during spinal cord operations, but whether IONM is necessary for posterior cervical surgeries for degenerative conditions is unknown. We evaluated the utility of somatosensory evoked potential (SSEP) and motor evoked potential (MEP) monitoring as a tool for predicting new postoperative neurologic deficits during posterior decompression and fusion for degenerative cervical spine conditions. We retrospectively reviewed posterior cervical operations performed at our institute over a 4-year period. Patients with postoperative neurologic deficits were identified, and a detailed analysis performed to ascertain whether SSEP or MEP monitoring accurately predicted the onset of new postoperative deficits. Overall, 498 patients were included in the analysis (median age 66 years; range: 22-93 years). SSEP monitoring was performed in all patients, and both SSEP and MEP monitoring were performed in 121 patients (24%). Twenty-one patients (4.2%) had new postoperative neurologic deficits. SSEP had significantly higher specificity (90%) but lower sensitivity (33%) than MEP (74% specificity [P= 0.008], 50% sensitivity [P= 0.01]) for detecting neurologic compromise intraoperatively. For SSEP, the positive predictive value (PPV) and negative predictive value (NPV) in detecting intraoperative changes that translated to new postoperative neurological deficits were 12% and 97%, respectively, whereas for MEP, the PPV and NPV were 6% (P= 0.009) and 98% (P= 0.20), respectively. IONM during posterior cervical operations for degenerative conditions of the spine is not reliable at predicting new postoperative neurologic deficits in patients treated for degenerative conditions, but may provide peace of mind to the surgeon intraoperatively when no abnormalities are detected.