Early Postoperative Magnetic Resonance Imaging Findings After Percutaneous Endoscopic Lumbar Discectomy and Their Correlations with Clinical Outcomes.

Abstract

To investigate the imaging features on early postoperative magnetic resonance imaging (MRI) after percutaneous endoscopic lumbar discectomy (PELD) and their correlations with surgical outcomes. Forty-seven patients with lumbar disc herniation who underwent PELD were enrolled in this study. MRI scans were performed 1 week and 3 months after surgery. Imaging features on these MRI scans were evaluated. Clinical factors that might affect surgical outcomes were recorded. Multivariate logistic regression analysis was performed to assess all potential factors affecting short-term and midterm outcomes after PELD. On MRI scans 1 week postoperatively, a residual mass at the operated site was observed in 93.6% of cases. Of those, ipsilateral nerve root compression was observed in 70.2% of cases. These residual masses had intermediate signal intensity on Tl-weighted images but either hyperintensity (56.8%) or intermediate intensity (43.2%) on T2-weighted images. On MRI scans 3 months postoperatively, the residual masses had vanished in 82.8% of cases. Based on the results of logistic regression analysis, symptom duration <1 year (P= 0.033) and high T2 signal intensity of the residual mass (P= 0.004) correlated with better short-term outcomes. However, no factor was correlated with midterm outcomes. A residual mass with ipsilateral nerve root compression on early postoperative MRI after PELD is common. Most of these residual masses will vanish within 3 months. "Nerve root compressed by a residual mass" on early postoperative MRI does not affect surgical outcomes. "High T2 signal intensity of the residual mass" is associated with better short-term outcomes after PELD but not midterm outcomes.