title: Transforaminal percutaneous endoscopic lumbar discectomy for very high-grade migrated disc herniation.
abstract: OBJECTIVE
  Transforaminal percutaneous endoscopic lumbar discectomy (PELD) for high-grade migrated disc herniation has been regarded as a challenging task, but because of the remarkable improvement in navigable instruments and advanced epiduroscopic technique, it can be used for the treatment of high- or very high-grade migrated disc herniation. The purpose of this study was to describe in detail the standardized technique of transforaminal PELD for very high-grade migrated disc herniation and demonstrate the clinical results.
  
  
  METHODS
  Very high-grade lumbar migrated disc herniation was defined as a disc migration beyond the inferior margin of the pedicle. Thirteen consecutive patients with very high-grade lumbar migrated disc herniation were treated with transforaminal PELD, which has three stages: (1) direction-oriented transforaminal approach, (2) release of periannular anchorage, and (3) epiduroscopic fragmentectomy with navigable instruments. The surgical outcomes were assessed using the visual analogue pain score (VAS), Oswestry disability index (ODI), and modified Macnab criteria.
  
  
  RESULTS
  The operated levels were L3-4 in 2 (15.4%) patients, L4-5 in 10 (76.9%), and L5-S1 in 1 (7.7%). The directions of migration were cranial in 8 patients and caudal in 5. The mean VAS for leg pain improved from 7.86±1.28 preoperatively to 2.54±1.51 at 6 weeks postoperatively and 1.85±1.07 at 1year postoperatively (P<0.01). The mean preoperative ODI improved from 84.92±6.36 preoperatively to 27.83±7.34 at 6 weeks postoperatively and 17.54±13.40 at 1year postoperatively (P<0.01). Excellent or good global outcomes were obtained in 84.6%, and the rate of symptomatic improvement was 92.3%.
  
  
  CONCLUSIONS
  Transforaminal PELD can be effective for very high-grade migrated lumbar disc herniation, and a standardized technique may provide a reliable and reproducible result.
authors.affiliation: Department of Neurosurgery, Gachon University Gil Medical Center, Incheon, South Korea. Electronic address: ns-ay@hanmail.net.
authors.forename: Yong
authors.initials: Y
authors.lastname: Ahn
authors.affiliation: Department of Neurosurgery, Nanoori Hospital, Seoul, South Korea.
authors.forename: Il-Tae
authors.initials: IT
authors.lastname: Jang
authors.affiliation: Department of Neurosurgery, Gachon University Gil Medical Center, Incheon, South Korea.
authors.forename: Woo-Kyung
authors.initials: WK
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D017587:Diskectomy, Percutaneous / Q000379:methods*; D005260:Female; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care
keywords: Discectomy; Full-endoscopic; Lumbar; Migrated disc herniation; Percutaneous endoscopic; Transforaminal