title: Hidden compartments in AVMs--a new concept.
abstract: OBJECTIVE
  The concept of hidden compartments in cerebral arteriovenous malformations (AVMs), which is hereby launched, offers a new explanation for the neurosurgical and neuroradiological controversies concerning patients with AVMs.
  
  
  METHODS
  Three patients who were considered completely cured of their AVMs, subsequently developed new areas of malformed vessels as revealed by later angiograms.
  
  
  RESULTS
  These 3 cases support our hidden compartment hypothesis and are reported on here, illustrated with relevant angiograms. The clinical implications of the hidden compartment concept refer to phenomena such as AVM growth, AVM recurrence after surgical excision, irradiation or embolization as well as per- or postoperative hemorrhage and swelling.
  
  
  CONCLUSIONS
  The incidence of hidden compartments in the AVM population is unknown but further studies, particularly in the realm of superselective embolization, could reveal their presence.
authors.affiliation: Department of Neurosurgery, Sahlgren's University Hospital, Gothenburg, Sweden.
authors.forename: L
authors.initials: L
authors.lastname: Pellettieri
authors.forename: P
authors.initials: P
authors.lastname: Svendsen
authors.forename: G
authors.initials: G
authors.lastname: Wikholm
authors.forename: C A
authors.initials: CA
authors.lastname: Carlsson
mesh_terms: D000328:Adult; D002533:Cerebral Angiography; D002543:Cerebral Hemorrhage / Q000000981:diagnostic imaging / Q000209:etiology; D004621:Embolization, Therapeutic; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000150:complications / Q000000981:diagnostic imaging* / Q000628:therapy; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000209:etiology; D011878:Radiotherapy; D012008:Recurrence