Abstract
BACKGROUND CONTEXT A far lateral herniated nucleus pulposus (HNP) consists of 7%-12% of all disc herniations. 'Far lateral' is often used to describe a lumbar disc herniation that compresses the exiting nerve root at the same level, lateral to the neural foramen. The far lateral disc herniations have been described to elicit radicular leg pain that is more severe than a central or paracentral lumbar disc herniation due to direct compression of dorsal root ganglion, and are said to have a more acute onset in their clinical symptoms. However, literature does not provide much description of the comparative postoperative outcomes between those presenting with a far lateral HNP and those with a central or paracentral herniation. PURPOSE The goal of this study is to examine the pre- and postoperative outcomes between patients presenting with a central or paracentral versus a far lateral HNP. STUDY DESIGN/SETTING Retrospective cohort series. PATIENT SAMPLE We performed a retrospective cohort analysis of patients who underwent a primary lumbar microdiscectomy between 2009 and 2015 by one of two senior orthopaedic spine surgeons for lumbar spinal stenosis. Patients were excluded from analysis if they had any previous lumbar surgery, an unstable spondylolisthesis, were under 18 years of age at the time of surgery, or had postoperative follow up less than 3 months. Patients were divided into two groups based on the location of the HNP (central or paracentral versus far-lateral). OUTCOME MEASURES Patient reported outcomes were obtained in the form of Oswestry Disability Index (ODI) scores, Visual Analog Scales (VAS) scores for the back and leg, 12-Item Short Form Mental and Physical Survey (SF-12) scores, and the Veterans Rand 12-Item Health Mental and Physical Survey (VR-12) scores. METHODS Baseline patient characteristics were compared using chi-squared analysis and independent sample t-tests for categorical and continuous data, respectively. Bivariate and multivariate regressions were subsequently used to compare clinical outcomes between procedure groups. Multivariate analyses controlled for differences in baseline patient characteristics. RESULTS Overall, 212 consecutive patients who fulfilled our inclusion criteria were assessed. Average follow-up was 24.14 months (range 3–78 months). There were 191 patients who presented with a central or paracentral HNP, while 21 patients presented with a far-lateral HNP. There were no significant differences in the demographic variables between these two groups. Patients with a far lateral disc herniation presented with a trend towards a shorter duration of symptoms prior to surgery (24.5 vs. 31.5 months; p=.052). On multivariate analysis, patients with a far lateral disc herniation presented with significantly lower SF-12 mental (52.14±13.49 vs. 55.1±6.55; p=.034) and physical scores (24.76±7.5 vs. 36.9±11.1; p=.008). Similarly, the far-lateral disc herniation patients also presented with significantly lower VR-12 mental (47.2±12.8 vs. 56.9±7.0; p=.024) and physical scores (25.8±8.7 vs.39.38±11.8; p=.005). However, postoperatively, all patients have similar SF-12 and CR-12 survey scores. The improvement in ODI score was significantly lower in the patients presenting with a far lateral disc herniation (7.8±15.1 vs. 28.3±21.5; p=.002). No significant difference in re-operation rates was found (p=.236). CONCLUSIONS Patients presenting with far lateral disc herniations present with significantly lower SF-12 mental and physical scores as well as lower VR-12 mental and physical scores. However, at approximately 2 years following a lumbar microdecompression surgery, both groups of patients express similar successful outcomes, including SF-12 and VR-12 survey scores. Re-operation rates are similar between the two groups. Despite compression at the site of the dorsal root ganglion and the reported greater difficulty in addressing far lateral disc herniations, patients presenting with these far lateral disc herniations can expect similar outcomes to those patients present with herniations in the central or paracentral region.
Published Version
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