Intraoperative neurophysiological monitoring (IONM) or intraoperative neuromonitoring is the use of electrophysiological methods such as electroencephalography (EEG), electromyography (EMG), and evoked potentials to monitor the functional integrity of certain neural structures (e.g., nerves, spinal cord and parts of the brain) during surgery.
The purpose of IONM is to reduce the risk to the patient of iatrogenic damage to the nervous system, and/or to provide functional guidance to the surgeon and anesthesiologist.
Neuromonitoring employs various electrophysiologic modalities, such as extracellular single unit and local field recordings, SSEP, transcranial electrical motor evoked potentials (TCeMEP), EEG, EMG, and auditory brainstem response (ABR).
[citation needed] To accomplish these objectives, a member of the surgical team with special training in neurophysiology obtains and co-interprets triggered and spontaneous electrophysiologic signals from the patient periodically or continuously throughout the course of the operation.
Patients who benefit from neuromonitoring are those undergoing operations involving the nervous system or which pose risk to its anatomic or physiologic integrity.
Interactive software running on the system carries out two tasks: The neurophysiologist can thus observe and document the electrophysiologic signals in realtime in the operating area during the surgery.
Differentiating the signal changes along these lines – with particular attention paid to stresses – is the joint task of the surgical triad: surgeon, anesthesiologist, and neurophysiologist.
More recently, transcranial electric motor evoked potentials (TCeMEP) have also been used for spinal cord monitoring.
This is the reverse of SSEP; the motor cortex is stimulated transcranially, and recordings made from muscles in the limbs, or from spinal cord caudal to the surgery.
The Certification for Neurophysiological Intraoperative Monitoring (CNIM) is awarded by the American Board of Electroencephalographic and Evoked Potential Technologists.
The exam has 200 multiple choice questions covering 6 areas: Anesthesia, Neuroscience, Instrumentation, Electro-physiology, Human physiology / anatomy, Surgical Applications.