Clinical Significance of Redundant Nerve Roots in Patients with Lumbar Stenosis Undergoing Minimally Invasive Tubular Decompression

Abstract

Symptomatic lumbar spinal stenosis (LSS) is a common indication for surgery in the elderly. Preoperative radiographic evaluation of patients with LSS often reveals redundant nerve roots (RNRs). The clinical significance of RNRs is uncertain. RNRs have not been studied in the setting of minimally invasive surgery. This study investigates the relationship between RNRs and clinical outcomes after minimally invasive tubular decompression. Chart review was performed for patients with degenerative LSS who underwent minimally invasive decompression. Preoperative magnetic resonance imaging parameters were assessed, and patient-reported outcomes were analyzed. Fifty-four patients underwent surgery performed at an average of 1.8±0.8 spinal levels. Thirty-one patients (57%) had RNRs. Patients with RNRs were older (median= 72years vs. 66years, P=0.050), had longer median symptom duration (32months vs. 15months, P<0.01), and had more levels operated on (2.1 vs. 1.4; P<0.01). The median follow-up after surgery was 2months (range= 1.3-12months). Preoperative and postoperative patient-reported outcomes were similar based on RNR presence. Patients without RNRs had larger lumbar cross-sectional areas (CSAs) (median= 121mm2 vs. 95mm2, P=0.014) and the index-level CSA (52mm2 vs. 34mm2, P=0.007). The CSA was not correlated with RNR morphology or location. Preoperative RNRs are associated with increased age, symptom duration, and lumbar stenosis severity. Patients improved after minimally invasive decompression regardless of RNR presence. RNR presence had no effect on short-term clinical outcomes. Further study is required to assess their long-term significance.