Neurophysiology, Intraoperative Monitoring, Neurodiagnostic Studies, CNIM Prep

What is IONM?

Intraoperative Neurophysiological Monitoring (IONM) is a system of equipment and tests used to evaluate and maintain the integrity of an individual’s brain, spinal cord, spinal pathways, and spinal nerves while undergoing a diagnostic, trauma, or elective procedure. These procedures are generally confined to spine and brain surgeries, but not always. During testing, the objective is to determine what findings are real/normal, abnormal, and outliers so that the necessary information can be provided to the surgeon, anesthesiologist, and or neurologist immediately to avoid causing unnecessary harm to the patient.

How it works

Having been around since the early 1970’s, industry founders such as Du Bois-Raymond, Caton and Han Berger pioneered several of the modalities (tests) used today. Most modalities can be simplified into stimulation and recording. Various points on the body can be chosen for a stimulation site as well as others for a recording site. At these points, a lead is placed allowing an electrical current to travel through the stimulated point, activating a nerve that sends an impulse through the spinal cord to the recording lead. These leads are connected to equipment that resembles a laptop and an external hard drive. The information is then presented on a screen in the form of a wave or action potential, to be interpreted by the neurophysiologist.

Why is it important?

The central nervous system (brain, spinal cord and spinal nerves) is responsible for a lot of what the body senses, how it moves and how we think and feel. When these areas are put at risk, whether it be from an elective or trauma surgery it is prudent to take all necessary precautions to try and protect and preserve those organs and avoid neurological insults. IONM information is instantaneous, allowing surgeons to know prudent changes that may take place during the surgery so that they can address it immediately. This has given rise to a growth in the field, because the numbers of positive post-operative outcomes have increased due to the avoidance of or the immediate correction of complications reported during procedures that use IONM. The risks to IONM patients are minimal, ranging from bruising and tenderness that may appear at the stimulation or recording site to possible skin infection.

What types of procedures use IONM?

There are many cases that use IONM, but we’ll name a few orthopedic, vascular, ENT and neurology cases:

  • Anterior cervical fusion
  • Posterior lumbar fusion
  • Scoliosis
  • Carotid endarterectomy
  • Thyroid
  • Parotid
  • Brain Tumor