Intraoperative neurophysiological monitoring (IONM) or intraoperative neuromonitoring employs recording, measuring and analyzing electrophysiological signals during surgeries – in order monitor the functional integrity of certain neural structures, such as nerves, spinal cord and parts of the brain during surgery.

Intraoperative neurophysiological monitor is an electronic device for Intraoperative neurophysiological monitoring (IONM).

IONM methods include various electrophysiologic modalities such as electroencephalography (EEG), electromyography (EMG), and evoked potentials (EPs). 

Recorded EPs may include somatosensory (SSEP), transcranial electrical motor evoked potentials (TCeMEP), visual (VEPs), auditory brainstem response (ABR or BAEP).

The purpose of IONM is to reduce the risk of damage to the nervous system and/or to provide functional guidance to the surgeon and anesthesiologist.

For a given surgery, the set of modalities used depends in part on which neural structures are at risk. 

IONM techniques have significantly reduced the rates of morbidity and mortality without introducing additional risks, as well as costs.

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