Abstract Details

Title EMG, MEP, and SSEP in the Intraoperative Neurophysiologic Monitoring of Lumbar Surgeries

Topic Neuromuscular and Clinical Neurophysiology (EMG)

Presentation(s) P3 - Poster Session 3 (5:30 PM-6:30 PM)

Poster/Presentation
Number 1-009

Objective

To assess EMG, SSEP, and MEP changes in monitoring for neural damage during lumbar surgeries.

Background

Intraoperative Neurophysiologic Monitoring (IONM) is used to assess for and reverse damage during surgeries that place the nervous system at risk. Lumbar surgeries are done to address progressive spinal lesions or instability of the spinal column. Deficits occur when neural structures are damaged, for example, when local perfusion changes cause cord ischemia, or pedicle screws breach the spinal canal, or spinal correction mechanically strains the cord or roots. Postoperative weakness or numbness can result.

Design/Methods

A retrospective review of 100 lumbar surgical cases from August 2017 to July 2018 was performed via electronic medical records review of IONM reports, and pre- and post-operative exams. All included free running electromyography (EMG), 98 included transcranial motor evoked potentials (MEPs), and 32 included somatosensory evoked potentials (SSEPs).

Results IONM changes occurred in 7 cases: 6 involving EMG changes, 4 involving MEP changes, and 1 involving an SSEP change. Four had changes in multiple modalities. Two patients experienced new postoperative deficits, one of which experienced both EMG and MEP changes. The other involved no IONM changes, but rather, worsening of preoperative deficits in the setting of an expanding spinal epidural abscess causing cord compression. Some "false positives" may have resulted in postoperative deficits if not for interventions taken as a result of the IONM changes. For example, the only SSEP change occurred with an MEP change, both in the right arm, due to an unintended change in arm positioning, and resolved by repositioning the arm.

Conclusions EMG and MEP can be useful in monitoring for neural damage in lumbar surgeries. The only SSEP change occurred alongside an MEP change. Some "false positives" may be due to interventions done as a result of IONM changes to prevent postoperative deficits.

Authors/Disclosures
Viet Nguyen, MD PRESENTER	Dr. Nguyen has received personal compensation for serving as an employee of Biogen. Dr. Nguyen has stock in Biogen.
	No disclosure on file
	No disclosure on file
Leslie H. Lee, MD, FAAN	Dr. Lee has nothing to disclose.
Scheherazade Le, MD (Stanford University)	Dr. Le has nothing to disclose.
Jaime R. Lopez, MD (Stanford University School of Medicine)	An immediate family member of Dr. Lopez has received personal compensation for serving as an employee of AbbVie. Dr. Lopez has received personal compensation in the range of $500-$4,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Journal of Clinical Neurophysiology. Dr. Lopez has received personal compensation in the range of $10,000-$49,999 for serving as an Expert Witness for medical-legal consulting.

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