title: Intracranial Cerebral Artery Dissection of Anterior Circulation as a Cause of Convexity Subarachnoid Hemorrhage.
abstract: BACKGROUND
  Convexity subarachnoid hemorrhage (cSAH), defined as intrasulcal bleeding restricted to hemispheric convexities, has several etiologies: reversible cerebral vasoconstriction syndrome, cerebral amyloid angiopathy, and internal carotid artery (ICA) stenosis or occlusion. However, it remains unknown whether cerebral artery dissection causes cSAH.
  
  
  METHODS
  We retrospectively investigated patients admitted to our hospital between 2005 and 2013 with ischemic stroke or transient ischemic attack caused by cerebral artery dissection. Cerebral artery dissection was diagnosed by cervical or cerebral magnetic resonance imaging (MRI) or computed tomography (CT) showing a wall hematoma. CT angiography, ultrasonography, or intra-arterial digital-subtraction angiography detected cerebral artery dissection if a double lumen, string sign, intimal flap, or dissecting aneurysm was observed at a nonbifurcation site. We used CT or MRI to detect cSAH, which was defined as blood collection restricted to one or few cerebral sulci without extending to the basal cisterns, ventricles, or Sylvian and interhemispheric fissures. Demographic, neuroimaging, treatment, and prognostic data were collected.
  
  
  RESULTS
  In total, 82 patients were diagnosed with ischemic stroke caused by cerebral artery dissection. The following arteries were affected: the ICA (9 patients), anterior cerebral artery (ACA; 12 patients), middle cerebral artery (MCA; 12 patients), vertebral artery (37 patients), basilar artery (5 patients), posterior cerebral artery (2 patients), and posterior inferior cerebellar artery (4 patients). In addition, 1 patient presented with simultaneous dissection in both the vertebral and internal carotid arteries, and 6 patients (7%) presented with cSAH (3 men and 3 women, age 39-67 years). The MCA was dissected in four cases and the ACA in two cases, with cSAH frequencies of 33 (4 of 12) and 17% (2 of 12), respectively, in those vessels. Artery dissection in the vertebrobasilar artery system was not responsible for cSAH (0 of 48). In all the MCA dissection cases, cSAH occurred in the arterial border zone between the ACA and MCA territories. Although 2 patients showed early reperfusion with temporary cSAH enlargement, cSAH was self-limiting. Antithrombotic treatment did not complicate the clinical course when used in 4 patients during acute or subacute phases. All patients achieved a 3-month poststroke modified Rankin Scale of 0-2.
  
  
  CONCLUSIONS
  Our data suggest that cSAH caused by intracranial cerebral artery dissection is not rare. Further investigations are needed to elucidate the precise mechanism underlying cSAH in cerebral artery dissection.
authors.affiliation: Divisions of Neurology, Department of Stroke and Cerebrovascular Diseases, Suita, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Fukuma
authors.forename: Masafumi
authors.initials: M
authors.lastname: Ihara
authors.forename: Tomotaka
authors.initials: T
authors.lastname: Tanaka
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Morita
authors.forename: Kazunori
authors.initials: K
authors.lastname: Toyoda
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Nagatsuka
mesh_terms: D000328:Adult; D000368:Aged; D000784:Aortic Dissection / Q000150:complications* / Q000175:diagnosis / Q000628:therapy; D015901:Angiography, Digital Subtraction; D002533:Cerebral Angiography / Q000379:methods; D002536:Cerebral Arteries / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D005343:Fibrinolytic Agents / Q000627:therapeutic use; D006801:Humans; D002532:Intracranial Aneurysm / Q000150:complications* / Q000175:diagnosis / Q000628:therapy; D007564:Japan; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D020521:Stroke / Q000175:diagnosis / Q000209:etiology* / Q000628:therapy; D013345:Subarachnoid Hemorrhage / Q000175:diagnosis / Q000209:etiology* / Q000628:therapy; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D017585:Ultrasonography, Doppler, Transcranial
chemical_list: D005343:Fibrinolytic Agents