title: Midterm outcome after a microsurgical unilateral approach for bilateral decompression of lumbar degenerative spondylolisthesis.
abstract: OBJECTIVE
  The aim of this study was to evaluate the results and effectiveness of bilateral decompression via a unilateral approach in the treatment of lumbar degenerative spondylolisthesis (DS).
  
  
  METHODS
  Operations were performed in 84 selected patients (mean age 62.1 ± 10 years) with lumbar DS between the years 2001 and 2008. The selection criteria included lower back pain with or without sciatica, neurogenic claudication that had not improved after at least 6 months of conservative treatment, and a radiological diagnosis of Grade I DS and lumbar stenosis. Decompression was performed at 3 levels in 15.5%, 2 levels in 54.8%, and 1 level in 29.7% of the patients with 1 level of spondylolisthesis. All patients were followed up for at least 24 months. For clinical evaluations, a visual analog scale, Oswestry Disability Index (ODI), and Neurogenic Claudication Outcome Score (NCOS) were used. Spinal canal size and (neutral and dynamic) slip percentages were measured both pre- and postoperatively.
  
  
  RESULTS
  Neutral and dynamic slip percentages did not significantly change after surgery (p = 0.67 and p = 0.63, respectively). Spinal canal size increased from 50.6 ± 5.9 to 102.8 ± 9.5 mm(2) (p < 0.001). The ODI decreased significantly in both the early and late follow-up evaluations, and good or excellent results were obtained in 64 cases (80%). The NCOS demonstrated significant improvement in the late follow-up results (p < 0.001). One patient (1.2%) required secondary fusion during the follow-up period.
  
  
  CONCLUSIONS
  Postoperative clinical improvement and radiological findings clearly demonstrated that the unilateral approach for treating 1-level and multilevel lumbar spinal stenosis with DS is a safe, effective, and minimally invasive method in terms of reducing the need for stabilization.
authors.affiliation: Clinic of Neurosurgery, Şişli Etfal Education and Research Hospital, Istanbul, Turkey. mmusluman@yahoo.com
authors.forename: Ahmet Murat
authors.initials: AM
authors.lastname: Müslüman
authors.forename: Tufan
authors.initials: T
authors.lastname: Cansever
authors.forename: Adem
authors.initials: A
authors.lastname: Yılmaz
authors.forename: Halit
authors.initials: H
authors.lastname: Çavuşoğlu
authors.forename: İsmail
authors.initials: İ
authors.lastname: Yüce
authors.forename: Yunus
authors.initials: Y
authors.lastname: Aydın
mesh_terms: D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007796:Laminectomy / Q000379:methods*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008866:Microsurgery / Q000379:methods*; D008875:Middle Aged; D011859:Radiography; D013123:Spinal Fusion / Q000379:methods; D013168:Spondylolisthesis / Q000000981:diagnostic imaging / Q000601:surgery*; D016896:Treatment Outcome