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Published on: July 26, 2021
Return of motor evoked potentials after knee flexion in the setting of high-grade spondylolisthesis
Justin Tilan1, Lindsay M Andras2, Mark D Krieger3
1Department of Orthopaedic Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
Purpose:
To present a case of loss of motor-evoked potentials (MEPs) to the left foot in the supine position after a partial reduction and instrumented fusion from L4 to pelvis which was managed successfully without revision or removal of implants.
Methods:
We report a patient with high-grade spondylolisthesis who demonstrated loss of motor-evoked potentials after posterior spinal fusion and transfer to supine position. The patient's knees were flexed to 90° and signals were immediately restored. Systemic steroids were administered and circumferential fusion was delayed 21 days. Anterior-interbody cage was placed without complication.
Results:
She was discharged on post-operative day 2. At 7 months, she is pain free and doing well with plans to return to gymnastics completely.
Conclusions:
Knee flexion can be instituted when encountering a neuromonitoring signal change following posterior spinal fusion for spondylolisthesis as a means to alleviate acute nerve stretch injury and may in some cases prevent the need to lessen the correction.
Level Of Evidence:
IV.
