Intraoperative neurophysiological monitoring

Abstract Intraoperative neurophysiological monitoring (IOM) is a rapidly evolving field that enhances surgical safety and neurological outcomes. This chapter provides a comprehensive overview of IOM modalities used across a broad range of neurosurgical and spinal procedures. Techniques covered include electrocorticography (ECoG), direct cortical stimulation (DCD) and single-pulse electrical stimulation for functional mapping; electromyography (EMG), including free-run and triggered EMG for nerve root and cranial nerve monitoring; and peripheral and spinal stimulation methods such as train-of-four and dorsal column mapping. Motor evoked potentials (MEPs), including corticospinal D-waves and corticobulbar MEPs, are discussed alongside sensory evoked potentials—somatosensory (SSEPs), brainstem auditory (BAEPs) and visual (VEPs)—with the latter’s basic setup reviewed in Chapter 9. Brainstem reflexes, including the blink reflex, laryngeal adductor reflex, trigeminal-hypoglossal reflex and master H-reflex, are also explored. Practical guidance is provided on setup protocols, anaesthetic and physiological considerations, contraindications and troubleshooting. Typical interpretation patterns and clinical applications are discussed across common IOM scenarios, including vascular lesions, spinal and cauda equina pathology, brainstem monitoring, vestibular schwannoma and supratentorial tumour resections.