Can triggered electromyography monitoring throughout retraction predict postoperative symptomatic neuropraxia after XLIF? Results from a prospective multicenter trial
This multicenter study aims to evaluate the utility of triggered electromyography (t-EMG) recorded throughout psoas retraction during lateral transpsoas interbody fusion to predict postoperative changes in motor function.
Three hundred and twenty-three patients undergoing L4-5 minimally invasive lateral interbody fusion from 21 sites were enrolled. Intraoperative data collection included initial t-EMG thresholds in response to posterior retractor blade stimulation and subsequent t-EMG threshold values collected every 5 min throughout retraction. Additional data collection included dimensions/duration of retraction as well as pre-and postoperative lower extremity neurologic exams.
Prior to expanding the retractor, the lowestt-EMG threshold was identified posterior to the retractor in 94 % of cases. Postoperatively, 13 (4.5 %) patients had a new motor weakness that was consistent with symptomatic neuropraxia (SN) of lumbar plexus nerves on the approach side. There were no significant differences between patients with or without a corresponding postoperative SN with respect to initial posterior blade reading (p = 0.600), or retraction dimensions (p > 0.05). Retraction time was significantly longer in those patients with SN vs. those without (p = 0.031). Stepwise logistic regression showed a significant positive relationship between the presence of new postoperative SN and total retraction time (p < 0.001), as well as change in t-EMG thresholds over time (p < 0.001), although false positive rates (increased threshold in patients with no new SN) remained high regardless of the absolute increase in threshold used to define an alarm criteria.
CONCLUSIONS:Prolonged retraction time and coincident increases in t-EMG thresholds are predictors of declining nerve integrity. Increasing t-EMG thresholds, while predictive of injury, were also observed in a large number of patients without iatrogenic injury, with a greater predictive value in cases with extended duration. In addition to a careful approach with minimal muscle retraction and consistent lumbar plexus directional retraction, the incidence of postoperative motor neuropraxia may be reduced by limiting retraction time and utilizing t-EMG throughout retraction, while understanding that the specificity of this monitoring technique is low during initial retraction and increases with longer retraction duration.
|keywords||XLIF, DLIF, EMG, Lumbar Plexus, Neuropraxia, Transpsoas approach|
|citation||Külling F A. Can triggered electromyography monitoring throughout retraction predict postoperative symptomatic neuropraxia after XLIF? Results from a prospective multicenter trial. European Spine Journal 2015; 24:S378-385.|
|type||journal paper/review (English)|
|date of publishing||30-11-2015|
|journal title||European Spine Journal (24/Suppl 3)|
|contact||Fabrice Alexander Külling|