What is IONM

Intraoperative neuromonitoring (IONM) was developed due to the need to preserve nerves, nerve tracts and neurological functions.

One of the main techniques in IONM is identifying and localizing nerves (mapping) and to preserve them during surgical procedures. Being thus able to distinguish the tissue in the operation field, the surgeon can proceed more selectively and has a higher probability of not harming functional tissue. The second main technique uses evoked potentials during surgery to observe nerve integrity continuously and detect changes in nerve function as fast as possible. Hence, the surgeon can react immediately and is able to counteract, preventing permanent damage.

A lot of different approaches and methods were developed during the last years, tailored to various nerves and functional tracts. For instance, somatosensory evoked potentials (SSEPs) are triggered by the electrical stimulation of peripheral nerves (e.g. median or tibial nerve) and are recorded simultaneously at the brain’s primary sensory cortex. This technique helps to monitor the afferent nerve tracts. To monitor the efferent ones, motor evoked potentials (MEPs) can be used. By the electrical stimulation of the primary motor cortex, muscles in the patient’s body are activated. This electrical activity can be recorded to gain information about the motor pathway.

The patient’s benefit lies in the increased safety during surgery. Nerve function is preserved and side effects of the surgical procedure can be minimized. Thus, IONM contributes to a higher quality of life for patients after the surgery.

Surgeons profit from increased surgical safety, too They gain the possibility to do surgery without harming neural structures. Procedures can be performed more smoothly and resections more radical since nerve irritation is immediately detected and can be avoided.