title: Predictors of hemorrhage volume and disability after perimesencephalic subarachnoid hemorrhage.
abstract: OBJECTIVE
  The determinants of subarachnoid hemorrhage (SAH) volume and an atypical pattern of blood are not clear. Our objective was to determine if reduced platelet activity on admission and abnormal venous drainage are associated with greater SAH volume.
  
  
  METHODS
  We prospectively identified noncomatose patients with SAH without an identifiable aneurysm. We routinely measured platelet activity on admission and recorded aspirin use. SAH volumes were calculated with a validated technique. CT angiograms were reviewed by a certified neuroradiologist for venous drainage. Patients were followed for clinical outcomes through 3 months with the modified Rankin Scale (mRS). Data are Q1-Q3.
  
  
  RESULTS
  There were 31 patients in the cohort. Thirty (97%) underwent an angiogram on admission, and 25 (81%) an additional delayed angiogram. SAH volume was lowest with normal venous drainage bilaterally (4.4 [3.7-16.4] mL) and higher with 1 (12.9 [3.7-20.4]) or 2 (20.9 [12.5-34.6] mL, p = 0.03) discontinuous venous drainages. Patients with reduced platelet activity had more SAH on the diagnostic CT (17.5 [10.6-20.9] vs 6.1 [2.3-15.3] mL) (p = 0.046). SAH volume was greater for patients requiring drainage for hydrocephalus (16.4 [11.5-20.5] vs 5.4 [2.7-16.4] mL) (p = 0.009). Outcomes at 3 months were generally excellent (median mRS = 0, no symptoms).
  
  
  CONCLUSIONS
  Discontinuous venous drainage and reduced platelet activity were associated with increased SAH volume and hydrocephalus. These factors may explain thick SAH and reduce the need for repeated invasive imaging in such patients.
authors.affiliation: Northwestern University Feinberg School of Medicine, Chicago, IL, USA. a-naidech@northwestern.edu
authors.forename: A M
authors.initials: AM
authors.lastname: Naidech
authors.forename: N F
authors.initials: NF
authors.lastname: Rosenberg
authors.forename: M B
authors.initials: MB
authors.lastname: Maas
authors.forename: B R
authors.initials: BR
authors.lastname: Bendok
authors.forename: H H
authors.initials: HH
authors.lastname: Batjer
authors.forename: A J
authors.initials: AJ
authors.lastname: Nemeth
mesh_terms: D000328:Adult; D000368:Aged; D001241:Aspirin / Q000627:therapeutic use; D002533:Cerebral Angiography; D002550:Cerebral Veins / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology; D015331:Cohort Studies; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D006849:Hydrocephalus / Q000209:etiology / Q000601:surgery; D002532:Intracranial Aneurysm / Q000150:complications; D008297:Male; D008636:Mesencephalon / Q000098:blood supply / Q000473:pathology*; D008875:Middle Aged; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use; D010979:Platelet Function Tests; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D013345:Subarachnoid Hemorrhage / Q000097:blood* / Q000150:complications / Q000473:pathology*; D014057:Tomography, X-Ray Computed; D017287:Ventriculoperitoneal Shunt
chemical_list: D010975:Platelet Aggregation Inhibitors; D001241:Aspirin