title: Posterior interhemispheric approach: surgical technique, application to vascular lesions, and benefits of gravity retraction.
abstract: OBJECTIVE
  To review an experience with the posterior interhemispheric approach applied to vascular lesions in the posterior midline, to examine the effects of patient position and gravity retraction of the occipital lobe, and to identify circumstances requiring increased exposure by sectioning the falx and tentorium.
  
  
  METHODS
  During a 6.5-year period, 46 posterior interhemispheric approaches were performed to treat 28 arteriovenous malformations, 10 dural arteriovenous fistulae, seven cavernous malformations, and one posterior cerebral artery aneurysm. Twenty-three patients were positioned prone and 23 patient were positioned laterally.
  
  
  RESULTS
  A standard posterior interhemispheric approach was used in 38 patients, and the occipital bitranstentorial/falcine approach was used in seven patients. A contralateral occipital transfalcine approach was used with one thalamic cavernous malformation. All lesions were resected completely and/or obliterated angiographically, with good neurological outcomes in 83% of patients and no operative mortality. Blood loss was lower, operative durations were shorter, postoperative cerebral edema was decreased, and visual outcomes were improved in patients positioned laterally.
  
  
  CONCLUSIONS
  The posterior interhemispheric approach, without additional dural cuts, is appropriate for most vascular lesions in the posterior midline. Gravity retracts the occipital lobes when patients are positioned laterally, enhancing operative exposure and reducing morbidity. Extension of the posterior interhemispheric approach to a transtentorial or transfalcine approach is required for falcotentorial dural arteriovenous fistulae and vein of Galen arteriovenous malformations, but is not usually necessary with cavernous malformations or other arteriovenous malformations.
authors.affiliation: Department of Neurological Surgery, University of California, San Francisco, San Francisco, California 94143-0112, USA.
authors.forename: John H
authors.initials: JH
authors.lastname: Chi
authors.forename: Michael T
authors.initials: MT
authors.lastname: Lawton
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001164:Arteriovenous Fistula / Q000473:pathology / Q000601:surgery; D001165:Arteriovenous Malformations / Q000473:pathology / Q000601:surgery; D002648:Child; D004388:Dura Mater / Q000033:anatomy & histology / Q000601:surgery*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006112:Gravitation; D020786:Hemangioma, Cavernous, Central Nervous System / Q000473:pathology / Q000601:surgery; D006801:Humans; D002532:Intracranial Aneurysm / Q000473:pathology / Q000601:surgery; D007431:Intraoperative Complications / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000379:methods*; D009778:Occipital Lobe / Q000098:blood supply* / Q000601:surgery*; D020769:Posterior Cerebral Artery / Q000473:pathology / Q000601:surgery*; D012189:Retrospective Studies; D016896:Treatment Outcome; D014656:Vascular Surgical Procedures / Q000379:methods*