Monitoring lumbar plexus integrity in extreme lateral transpsoas approaches to the lumbar spine: a new protocol with anatomical bases

XLIF is an increasingly popular procedure that requires traversing the psoas, with the potential risk of injuring the lumbar plexus nerves. Intraoperative neurophysiological monitoring (IOM) is, therefore, critical in this kind of procedures; nevertheless, there were some reports of neural damage. To determine the effectiveness of a new protocol for IOM during XLIF. This prospective, nonrandomized, institutional review board-approved study enrolled adult patients of both sexes undergoing XLIF at the Italian Hospital of Buenos Aires between 2012 and 2014. Preoperative and immediate postoperative neurological examinations were carried out, paying special attention to lumbar plexus motor and sensory territories. IOM included EMG and transpsoas stimulation, considering the territories of every motor and sensory branch of the lumbar plexus. 107 patients (133 lumbar levels) were evaluated. Reproducible responses were obtained in the collateral and terminal branches of the lumbar plexus, which were well preserved. No patient (0 %) had new motor postoperative deficits. Nineteen (17.75 %) patients had minor and transient sensory symptoms, lasting less than a month. One patient (0.93 %) had longer duration of sensory complaints (3 months). A detailed IOM of lumbar plexus branches can determine in real time the proximity of intrapsoas nerves during XLIF.