title: Hemifacial spasm: neurovascular compressive patterns and surgical significance.
abstract: BACKGROUND
  The aim of this study was to report further investigation of neurovascular compression as a cause of hemifacial spasm (HFS) and to provide useful surgical guidelines by describing the compression patterns.
  
  
  METHODS
  From January 2004 to February 2006, 236 consecutive patients with HFS underwent microvascular decompression (MVD) in a single centre. Based on the operation and medical records, the intraoperative findings and post-operative outcomes were obtained and analysed.
  
  
  RESULTS
  We found that 95.3% of lesions had accompanying causative factors that made the neurovascular compression inevitable. Based on the contributing factors, compression patterns were categorised into six different types including: loop (n = 11: 4.6%), arachnoid (n = 66: 27.9%), perforator (n = 58: 24.6%), branch (n = 18: 7.6%), sandwich (n = 28: 11.9%), and tandem (n = 52: 22.0%). The compression patterns were significantly correlated with the compressing vessels involved. Thirty-two (86.5%) of 37 lesions where the vertebral artery was the compressing vessel involved the tandem type. Anterior inferior cerebellar artery was the compressing vessel involved in 49 (84.5%) of 58 perforator type compressions, while posterior inferior cerebellar artery was the compressing vessel involved in 8 (72.7%) of 11 loop type compressions.
  
  
  CONCLUSIONS
  Once the compressing vessel responsible for the neurovascular compression are identified, the probable pattern of compression can be anticipated; this knowledge could facilitate the application of the appropriate operative procedures and minimise post-operative complications.
authors.affiliation: Samsung Medical Center, Department of Neurosurgery, School of Medicine, Sungkyunkwan University, Seoul, South Korea.
authors.forename: J S
authors.initials: JS
authors.lastname: Park
authors.forename: D-S
authors.initials: DS
authors.lastname: Kong
authors.forename: J-A
authors.initials: JA
authors.lastname: Lee
authors.forename: K
authors.initials: K
authors.lastname: Park
mesh_terms: D000328:Adult; D001488:Basilar Artery / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D002530:Cerebellopontine Angle / Q000033:anatomy & histology / Q000098:blood supply / Q000601:surgery; D002531:Cerebellum / Q000098:blood supply; D002561:Cerebrovascular Disorders / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D019299:Decompression, Surgical / Q000379:methods / Q000592:standards; D005154:Facial Nerve / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D005155:Facial Nerve Diseases / Q000209:etiology* / Q000503:physiopathology* / Q000601:surgery; D005260:Female; D019569:Hemifacial Spasm / Q000209:etiology* / Q000503:physiopathology* / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D009408:Nerve Compression Syndromes / Q000209:etiology* / Q000503:physiopathology / Q000601:surgery; D019635:Neurosurgical Procedures / Q000379:methods / Q000592:standards; D011183:Postoperative Complications / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control; D016896:Treatment Outcome; D014656:Vascular Surgical Procedures / Q000379:methods / Q000592:standards