title: The mid-M1 segment of the middle cerebral artery is a cutoff clot location for good outcome in intravenous thrombolysis.
abstract: OBJECTIVE
  We studied the impact of the location of the thrombus (internal carotid artery, proximal M1 segment, distal M1 segment, M2 segment, and M3 segment of the middle cerebral artery) in predicting the clinical outcome of patients treated with intravenous thrombolytic therapy (<3 h) in a retrospective cohort.
  
  
  METHODS
  Anterior circulation thrombus was detected with computed tomography angiography in 105 patients. Baseline clinical and radiological information was collected and entered into logistic regression analysis to predict favorable clinical outcome (3-month modified Rankin Scale from 0 to 2 was a primary outcome measure).
  
  
  RESULTS
  Three months after stroke, there was a significant increase in mortality (32% vs. 3%, P < 0.001) and functional dependency (82% vs. 29%, P < 0.001) in patients with internal carotid artery or proximal M1 segment of the middle cerebral artery thrombus compared to a more distal occlusion. In the regression analysis, after adjusting for National Institutes of Health Stroke Scale, age, sex, and onset-to-treatment time, the clot location was an independent predictor of good clinical outcome (P = 0.001) and exhibited dose-response type behavior when moving from a proximal vessel position to a more distal one. When the location was dichotomized, a cutoff between the proximal and the distal M1 segments best differentiated between good and poor clinical outcome (OR = 16.0, 95% CI 3.9-66.2).
  
  
  CONCLUSIONS
  The outcome of acute internal carotid artery or proximal M1 segment of the middle cerebral artery occlusion is generally poor even if treated with intravenous thrombolysis. Alternative revascularization strategies should be considered. Vascular imaging at the admission is required to guide this decision.
authors.affiliation: Department of Neurology, Tampere University Hospital, Tampere, Finland. jukka.saarinen@uta.fi
authors.forename: J T
authors.initials: JT
authors.lastname: Saarinen
authors.forename: N
authors.initials: N
authors.lastname: Sillanpää
authors.forename: H
authors.initials: H
authors.lastname: Rusanen
authors.forename: J
authors.initials: J
authors.lastname: Hakomäki
authors.forename: H
authors.initials: H
authors.lastname: Huhtala
authors.forename: A
authors.initials: A
authors.lastname: Lähteelä
authors.forename: P
authors.initials: P
authors.lastname: Dastidar
authors.forename: S
authors.initials: S
authors.lastname: Soimakallio
authors.forename: I
authors.initials: I
authors.lastname: Elovaara
mesh_terms: D000368:Aged; D002533:Cerebral Angiography; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D020244:Infarction, Middle Cerebral Artery / Q000000981:diagnostic imaging* / Q000188:drug therapy* / Q000473:pathology*; D008297:Male; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000473:pathology; D020127:Recovery of Function; D012189:Retrospective Studies; D015912:Thrombolytic Therapy / Q000379:methods*