title: Microsurgical resection of brainstem, thalamic, and basal ganglia angiographically occult vascular malformations.
abstract: OBJECTIVE
  To evaluate the clinical results for patients who underwent resection of angiographically occult vascular malformations (AOVMs) of the brainstem, thalamus, or basal ganglia, successfully resected after it exhibited rebleeding and presented to a pial surface.
  
  
  METHODS
  Between January 1990 and May 1998, 56 patients with 57 deep AOVMs underwent 63 operations, at Stanford University Medical Center, to treat AOVMs of the brainstem (42 AOVMs), thalamus (5 AOVMs), or basal ganglia (10 AOVMs). The surgical approach was suboccipital midline (27 operations), far lateral suboccipital (10 operations), transsylvian (9 operations), interhemispheric transcallosal or infracallosal (8 operations), infratentorial supracerebellar (6 operations), or subtemporal (3 operations). Four patients experienced recurrent bleeding from the same lesion after surgical resection, requiring a second operation. One patient required a planned second operation, using a different approach, to completely resect the lesion, and one patient underwent two surgical procedures to resect two separate brainstem AOVMs. One patient initially underwent exploration but not resection of her AOVM, because it did not present to a pial or ependymal surface. The AOVM was successfully resected after it exhibited rebleeding and presented to a pial surface.
  
  
  RESULTS
  The immediate outcomes after surgery were unchanged for 31 patients (55%), worsened for 16 (29%), and improved for 9 (16%). The long-term outcomes were unchanged for 24 patients (43%), compared with their presenting grade, worse for 3 (5%), and improved for 29 (52%). Patients who had undergone previous radiotherapy or radiosurgery to treat these lesions experienced more difficult postoperative courses, and radiation necrosis was observed for two patients.
  
  
  CONCLUSIONS
  AOVMs of the brainstem, thalamus, and basal ganglia can be safely removed, with a long-term neurological morbidity rate of only 5% and a complete lesion resection rate of 93% after the initial planned resection. The use of cranial base surgical approaches and intraoperative electrophysiological monitoring contributes to successful clinical outcomes.
authors.affiliation: Department of Neurosurgery and Stanford Stroke Center, Stanford University School of Medicine, California 94305, USA.
authors.forename: G K
authors.initials: GK
authors.lastname: Steinberg
authors.forename: S D
authors.initials: SD
authors.lastname: Chang
authors.forename: R J
authors.initials: RJ
authors.lastname: Gewirtz
authors.forename: J R
authors.initials: JR
authors.lastname: Lopez
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001479:Basal Ganglia / Q000098:blood supply* / Q000601:surgery; D001933:Brain Stem / Q000098:blood supply* / Q000601:surgery; D002533:Cerebral Angiography; D002543:Cerebral Hemorrhage / Q000175:diagnosis / Q000601:surgery; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000175:diagnosis / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008297:Male; D008866:Microsurgery; D008875:Middle Aged; D009460:Neurologic Examination; D011183:Postoperative Complications / Q000175:diagnosis / Q000601:surgery; D011237:Predictive Value of Tests; D012086:Reoperation; D013788:Thalamus / Q000098:blood supply* / Q000601:surgery; D016896:Treatment Outcome