Intraoperative neuromonitoring (IONM) tracks the functional integrity of the nervous system in real time during procedures that place neural structures at risk. By detecting changes before they become permanent, IONM gives the surgical team a chance to intervene and prevent injury.
Core modalities
- Somatosensory evoked potentials (SSEP) assess the dorsal-column sensory pathway.
- Motor evoked potentials (MEP) evaluate the corticospinal motor tract.
- Electromyography (EMG) — free-running and triggered — monitors nerve-root and peripheral-nerve function.
- Electroencephalography (EEG) tracks cortical activity, useful in carotid and cerebrovascular surgery.
Signal processing
Raw neural signals are small and buried in electrical noise. Averaging repeated responses, filtering, and artifact rejection extract a reliable waveform. Modern systems display trends over time so that gradual drift is distinguished from abrupt change, and integrate multiple modalities to build a fuller picture of neural status.
Alert thresholds
Commonly applied warning criteria include a significant amplitude reduction or latency increase in SSEP, and amplitude decline or threshold elevation in MEP. When a signal crosses the alert threshold, the team systematically reviews technical, anesthetic, physiologic, and surgical causes — from blood pressure and temperature to retraction and instrumentation — before deciding on corrective action.
Clinical value and teamwork
IONM is widely used in spinal deformity correction, intramedullary and skull-base tumor resection, and cerebrovascular surgery. Its value depends on close communication among the surgeon, neurophysiologist, and anesthesiologist, and on stable anesthetic conditions that preserve interpretable signals.
INVAMED technologies in this space
INVAMED develops neurosurgical and spine instrumentation; explore the neuro, spine and cranial category.
Device availability and approved indications vary by country. This content is prepared for healthcare professionals and does not replace clinical judgment or the instructions for use.