Indications for prophylactic lumbar decompression at the L3/4 level in patients with L4/5 responsible lumbar spinal canal stenosis

ORIGINAL ARTICLE

Toru Asari1)2), Shuichi Aburakawa1), Gentaro Kumagai1)2), Sunao Tanaka1)2), Yasuyuki Ishibashi2)

1) Department of Orthopedic Surgery, Aomori Rosai Hospital, Hachinohe, Aomori, Japan
2) Department of Orthopedic Surgery, Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan

Abstract:

Introduction: Lumbar spinal canal stenosis (LSS) is a very common disease. When the responsible level is considered to be L4/5 despite the appearance of double-level (L3/4 and L4/5) stenosis on magnetic resonance imaging (MRI), it is difficult for spinal surgeons to decide whether prophylactic decompression should be performed at the L3/4 level. The purpose of this study was to investigate the relationship between the dural sac cross-sectional area (DCSA) at the L3/4 level and clinical symptoms in patients with double-level stenosis.
Methods: Thirty-five patients with double-level stenosis were registered in this study. All patients underwent decompression surgery at the L4/5 responsible level. The severity of patients' symptoms was evaluated by the Japanese Orthopaedic Association (JOA) score and its rate of recovery. A measurement program on MRI was used to determine the DCSA.
Results: The clinical course of LSS according to the JOA score recovery rate at the final follow-up revealed that the good group (≥50%) included 27 patients, and the poor group (<50%) included 8 patients. In the good group, the mean DCSA at the L3/4 level was 72.3 ± 32.1 mm2 preoperatively and 71.3 ± 29.0 mm2 at the final follow-up. In contrast, in the poor group, the mean DCSA at the L3/4 level was 49.1 ± 23.8 mm2 preoperatively and 40.6 ± 14.1 mm2 at the final follow-up. Significant differences were observed in the preoperative and final follow-up DCSAs at the L3/4 level between two groups.
Conclusions: Considering the present results, prophylactic decompression surgery at the L3/4 level should be performed for patients with double-level stenosis and DCSA <50 mm2 at the L3/4 level.

Released: October 27, 2017; doi: dx.doi.org/10.22603/ssrr.1.2016-0032