Intraoperative Neurophysiological Monitoring (IONM) for Sciatica
October 05, 2020
Copious amounts of attention are granted to the sedentary lifestyle epidemic that has befallen humanity. To a certain degree, this is for a good reason, and people are meant to move. We imagine a healthy lifestyle as being epitomized by an active lifestyle - all things in moderation, though, as they say. While keeping you active and on your feet, manual labor has its pool of potential detriments to your physical well-being.
Radiculopathy, commonly known as a pinched nerve, results from the compression or irritation of nerves as they exit the spine. The most common type of radiculopathy is specific to the spine's lumbar region or the lower back. Nerves of the lumbar spine control and supply sensation to leg muscles and the buttocks. Naturally, lumbar radiculopathy is characterized by lower back pain and pain that extends down into the lower extremities. This might sound familiar. This combination of symptoms is commonly known as sciatica. The people most at risk for developing lumbar radiculopathy aren't typically those who sit behind a desk, they're the people involved in heavy lifting and contact sports.
Enter a 59-year-old man with a history of lower back pain, specifically pain extending down to his calves and thighs, and radiating pain from the hips down as well as a combination of numbness and tingling in his toes and shins. Further complicating his condition, the man also suffered from spondylolisthesis in the lumbar region and spondylolysis in the lumbar region. Meaning one of his lower vertebrae had slipped out of position and onto the bones below it.
The patient had already undergone a previous spinal fusion surgery too, which resulted in a pseudoarthrosis. Pseudoarthrosis is nonunion of the vertebrae being fused or a failure to complete spinal fusion. Because the fusion was not able to completely heal on its own, a second surgery was required.
To alleviate the patient's lumbar radiculopathy, spondylolisthesis, and spondylolysis pain in addition to his pseudoarthrosis, an L3-S1 Decompression and L4-5 Posterior Spinal Lumbar Fusion were performed. Like any surgery, spinal fusion carries with it risks to the patient. However, due to the nature of spinal surgery and the potential implications for damage to the spinal cord, the risks are much greater.
"Specifically in the case of lumbar fusion surgery, damage to the spinal cord in this area could carry with it serious complications. Anything from persistent pain to paralysis, incontinence, or sexual impairment," said Dr. Faisal R. Jahangiri of AXIS Neuromonitoring in Richardson, Texas. It is for this very reason intraoperative neurophysiological monitoring was crucial for a positive outcome for the patient.
During the plate and screw placements to complete the patient's lumbar fusion, the AXIS technologist alerted the surgeon of significant decreases in amplitude from numerous sensors. These decreases were measured from the lower extremity Motor Evoked Potentials (MEP) and SSEPs, or Somatosensory Evoked Potentials, except the left posterior tibial nerve. These drops in amplitude can be predictive of a decrease in sensation to the patient's legs and feet.
"Intraoperative neuromonitoring reduces the risk of neurological injuries to a patient during surgery, which may not be evident until after the operation is complete," said Jahangiri.
Without neuromonitoring, sensory changes would not have been identified. A lack of intraoperative neuromonitoring, in conjunction with improper positioning, would likely have resulted in ischemia and stretching or compression of the nerves resulting in a brachial plexus injury. In other words, the patient would have suffered postoperative muscle weakness, numbness, severe pain, and/or burning sensations.