title: A Strategy of Percutaneous Endoscopic Lumbar Discectomy for Migrated Disc Herniation.
abstract: OBJECTIVE
  Percutaneous endoscopic lumbar discectomy (PELD) with remarkable advancements has led to successful results comparable with open discectomy; however, its application in herniated disc (HD) with migration is still challenging and technically demanding. The purpose of this study is to propose various strategies for PELD according to HD with migration.
  
  
  METHODS
  A retrospective review was performed on 434 consecutive patients who had undergone PELD. HD with migration was classified into 4 zones: low-grade up/down and high-grade up/down based on the extent and direction of migration. Clinical outcomes were assessed by visual analogue scale score for back and leg pain, Oswestry Disability Index, and modified Macnab criteria. Endoscopic approaches and techniques were analyzed depending on HD with migration.
  
  
  RESULTS
  A total of 149 patients underwent PELD for HD with migration. There were 93 low-grade down HD patients, 13 high-grade down, 11 low-grade up, and 32 high-grade up. High-grade up HDs were removed with the outside or outside-in techniques from L1-2 to L4-5. High-grade down HDs were removed via the outside technique with additional foraminoplasty. Low-grade up/down HDs with disc space continuity were removed with the inside-out technique. Meanwhile, at the L5-S1 level, interlaminar PELD was used to treat high-grade up/down HD with migration. The mean visual analogue scale score for back pain, leg pain, and Oswestry Disability Index were significantly improved after PELD. Favorable outcome was achieved in 90.6% of cases.
  
  
  CONCLUSIONS
  An appropriate strategy for PELD is important for successful removal of HD considering the extent of migration and direction.
authors.affiliation: Department of Neurosurgery, The Leon Wiltse Memorial Hospital, Anyang, Republic of Korea.
authors.forename: Kyung-Chul
authors.initials: KC
authors.lastname: Choi
authors.affiliation: Department of Neurosurgery, The Leon Wiltse Memorial Hospital, Anyang, Republic of Korea.
authors.forename: Dong Chan
authors.initials: DC
authors.lastname: Lee
authors.affiliation: Department of Neurosurgery, The Leon Wiltse Memorial Hospital, Anyang, Republic of Korea.
authors.forename: Hyeong-Ki
authors.initials: HK
authors.lastname: Shim
authors.affiliation: Department of Neurosurgery, The Leon Wiltse Memorial Hospital, Anyang, Republic of Korea.
authors.forename: Seung-Ho
authors.initials: SH
authors.lastname: Shin
authors.affiliation: Department of Neurosurgery, The Leon Wiltse Memorial Hospital, Suwon, Republic of Korea. Electronic address: allspine@gmail.com.
authors.forename: Choon-Keun
authors.initials: CK
authors.lastname: Park
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003131:Combined Modality Therapy / Q000706:statistics & numerical data; D019299:Decompression, Surgical / Q000706:statistics & numerical data*; D017587:Diskectomy, Percutaneous / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000453:epidemiology* / Q000473:pathology / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000473:pathology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures / Q000706:statistics & numerical data; D044583:Neuroendoscopy / Q000706:statistics & numerical data*; D010149:Postoperative Pain / Q000175:diagnosis / Q000453:epidemiology / Q000517:prevention & control*; D015995:Prevalence; D056910:Republic of Korea / Q000453:epidemiology; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome; D055815:Young Adult
keywords: Foraminoplasty; Inside-out; Migration; Outside; Percutaneous endoscopic lumbar diskectomy; Sequestration