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Intraoperative Neurophysiology Monitoring Unit (IONM)

The Intraoperative Neurophysiology Monitoring unit consists of a group of neurologists with formal training in clinical neurophysiology and IONM technologists, who work closely with other neurologists, surgeons and anesthesiologists at Massachusetts General Hospital to prevent postoperative neurologic deficit in a wide variety of surgical procedures.


Intraoperative neurophysiology is a fast growing field in neurology and clinical neurophysiology. Through an array of electrophysiological techniques, neurophysiologists are able to identify functional neural tissue, detect impending damage, localize the level of such damage within the neuroaxis and relay this information to surgeons during a variety of procedures. Neuro-monitoring and neuro-mapping prevent post-operative neurological deficit of the brain, brainstem, spinal cord, cranial and peripheral nerves.

Intraoperative neurophysiology has a significant positive impact for patient safety, enhances patient care, and is a great venue for neuroscience research.

About this Program

The Intraoperative Neurophysiology Monitoring (IONM) team at Massachusetts General Hospital is a professional team of neurologists and technologists with many years of IONM experience, who provide live functional guidance. We are present during any surgery in which there lies a high risk of neurological deficit. The IONM service is committed to improve neurological outcome after surgery.

As a whole, the team has been part of multidisciplinary care, working closely with members of the Neurology, Neurosurgery, Vascular Surgery, Orthopedic Surgery and Anesthesia Departments. Our physicians are board certified neurologists with formal training in all aspects of clinical neurophysiology (i.e. EEG, Evoked Potentials, and EMG).

The advanced technologies available at our institution enable us to continually set new standards in the field, and the IONM service conducts cutting edge research having as primary goal improvement of patient care and overall clinical outcome. We aim to better the various techniques and methods we utilize, to further protect and prevent postoperative neurologic deficit.


Contact Us

Mirela V. Simon, M.D.
Medical Director, Intraoperative Monitoring Unit
(617) 724-2655
Page: 31225

Request for Services

Page OR Neuromonitoring Beeper: #11581

We are a 24 hour on call service during the week. Please page the main pager and follow instructions. A timely response will follow.

IONM Fellowship



IOM Technologists

Office: (857) 238-5460

Aaron Tripp, R.EEG.T, CNIM

Chief Technologist


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