Pre-operative electrodiagnostic studies and intraoperative neurophysiologic monitoring: power and pitfalls

Outpatient electrodiagnostic studies and intraoperative monitoring are essential tools for the surgical management of nerve injury. Decisions are based on the diagnostic certainty afforded by outpatient electrodiagnostic studies, which are more sensitive and specific than clinical examinations regarding the nature and localization of a nerve lesion. Intraoperative neurophysiologic monitoring detects changes in neurologic function during surgery. It provides significantly better information than visual inspection of the operative field, minimizing postoperative neurologic deficits due to surgical manipulation (e.g., stretching, compression, heating from electrocauterization, constriction, or clamping of local blood vessels). These techniques exploit similar neurophysiologic principles to afford enhanced diagnostic and real-time functional data during surgery. However, an understanding of their limitations is critical for the interpretation of these data. This review discusses these techniques, including their use, advantages, and disadvantages in diagnosing and managing three essential nerve lesions amenable to surgical management-radiculopathy, mononeuropathy, and brachial plexopathy.