title: Supracerebellar-supratrochlear and infratentorial-infratrochlear approaches: gravity-dependent variations of the lateral approach over the cerebellum.
abstract: OBJECTIVE
  Lateral supracerebellar-infratentorial approaches are established for lesions in ambient cistern and posterolateral midbrain, but published surgical experiences do not describe results with this approach in the sitting position. Gravity retraction of the cerebellum opens this surgical corridor and dramatically alters exposure, creating 2 variations of the lateral supracerebellar-infratentorial approach: the supracerebellar-supratrochlear approach and the infratentorial-infratrochlear approach.
  
  
  METHODS
  We reviewed our experience treating cavernous malformations and arteriovenous malformations (AVMs) of the posteroinferior thalamus and posterolateral midbrain by use of supracerebellar-supratrochlear and infratentorial-infratrochlear approaches. Microsurgical technique, clinical data, radiographic features, and neurological outcomes were evaluated.
  
  
  RESULTS
  During an 11-year surgical experience with 341 cavernous malformation patients and 402 AVM patients, 8 patients were identified, 6 with cavernous malformations and 2 with AVMs. Infratentorial-infratrochlear approaches were used in 4 patients (50%), including 3 with inferolateral midbrain cavernous malformations. Supracerebellar-supratrochlear approaches were used in 4 patients (50%), including 2 with posterior thalamic lesions surfacing on pulvinar. Resections were radiographically complete in all cases. There were no new, permanent neurological deficits, nor were there any medical or surgical complications. There has been no evidence of rebleeding or recurrence.
  
  
  CONCLUSIONS
  Gravity retraction of the cerebellum transforms the lateral supracerebellar-infratentorial approach, enhancing exposure and approach trajectories that can be achieved with patients in prone or lateral positions. The increased upward viewing angle of the supracerebellar-supratrochlear approach accesses the posteroinferior thalamus. The increased downward-viewing angle of the infratentorial-infratrochlear approach accesses cerebellomesencephalic fissure and posterolateral midbrain. These approaches open wide corridors for safe surgical resection of symptomatic cavernous malformations and AVMs.
authors.affiliation: Department of Neurological Surgery, University of California at San Francisco, San Francisco, California 94143-0520, USA.
authors.forename: Nader
authors.initials: N
authors.lastname: Sanai
authors.forename: Zaman
authors.initials: Z
authors.lastname: Mirzadeh
authors.forename: Michael T
authors.initials: MT
authors.lastname: Lawton
mesh_terms: D000328:Adult; D002531:Cerebellum / Q000033:anatomy & histology / Q000601:surgery*; D035301:Cranial Fossa, Middle / Q000033:anatomy & histology / Q000098:blood supply / Q000601:surgery; D003399:Craniotomy / Q000379:methods*; D004388:Dura Mater / Q000033:anatomy & histology / Q000601:surgery; D005260:Female; D006112:Gravitation; D006392:Hemangioma, Cavernous / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D008297:Male; D008636:Mesencephalon / Q000033:anatomy & histology / Q000098:blood supply / Q000601:surgery; D008866:Microsurgery / Q000379:methods; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000379:methods*; D011859:Radiography; D012189:Retrospective Studies; D013346:Subarachnoid Space / Q000033:anatomy & histology / Q000601:surgery*; D013788:Thalamus / Q000033:anatomy & histology / Q000098:blood supply / Q000601:surgery; D055815:Young Adult