title: The accessory middle cerebral artery: anatomic report.
abstract: OBJECTIVE
  An accessory middle cerebral artery (MCA) usually originates between the A1 and proximal A2 segment of the anterior cerebral artery, reaches the sylvian fissure, and supplies the territory of the MCA. This anomaly has been associated with cerebral aneurysms and Moyamoya disease. We report an accessory MCA arising from the A2 segment.
  
  
  METHODS
  A cadaveric head, fixed in formalin solution and injected with red and blue silicone on its vascular tree to trace intracranial and extracranial vessels, was dissected.
  
  
  RESULTS
  An accessory MCA was found arising from the A2 segment of the anterior cerebral artery and feeding the basal and inferior surface of the inferior frontal gyrus. In our specimen, the vessel was associated with intracranial aneurysms at other locations.
  
  
  CONCLUSIONS
  Although anomalies of the MCA are rare, neurosurgeons must be familiar with such anatomic variations. An accessory MCA can be associated with Moyamoya disease and aneurysms at its junction with the anterior cerebral artery. Patients with this anomaly may, therefore, have an increased risk for developing aneurysms and other neurovascular complications. By obstructing the surgical view, an accessory MCA may increase the difficulty of exposing lesions in the vicinity of the optic chiasm.
authors: Division of Neurological Surgery and Neurosurgical Research, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona 85013, USA.
authors: Cassius V C
authors: CV
authors: Reis
authors: Joseph M
authors: JM
authors: Zabramski
authors: Sam
authors: S
authors: Safavi-Abbasi
authors: Ricardo A
authors: RA
authors: Hanel
authors: Pushpa
authors: P
authors: Deshmukh
authors: Mark C
authors: MC
authors: Preul
mesh_terms: D001921:Brain / Q000098:blood supply* / Q000601:surgery; D002533:Cerebral Angiography / Q000379:methods; D006801:Humans; D020768:Middle Cerebral Artery / Q000002:abnormalities* / Q000033:anatomy & histology* / Q000601:surgery; D019635:Neurosurgical Procedures / Q000379:methods