Your anesthesiologist (the person that puts you to sleep) uses an array of techniques to monitor your heart and lungs during surgery.  These include tools to measure your heart-rate, blood pressure, blood oxygen and carbon dioxide content, and temperature.

While this monitoring gives your surgeon and anesthesiologist a good picture of the status of your heart and lungs during surgery, it is more difficult for them to tell if there is anything wrong with your nervous system. For surgeries that place your nervous system at risk, such as those to stabilize the spine, decompress the spinal cord or remove abnormal brain tissue, IOM is used to avoid or minimize injury during surgery.

IOM is an assortment of monitoring tools or techniques used by your surgeon to obtain a picture of the function of your nervous system at various points during surgery.

During IOM testing, brain waves are recorded in response to several types of stimuli including small electrical pulses applied to peripheral nerves, flashes of light to the eyes, and clicks of sound to the ears. Muscles are also monitored for abnormal electrical activity that might suggest injury to the nerve supplying them.

These tests allow your surgeon to assess the integrity of the part of the nervous system that he is working on or near, ensuring a quick response to any sign of potential injury and/or dysfunction.  There are no lasting side effects from IOM stimulation.