title: Risk factors for acute subdural hematoma from intracranial aneurysm rupture.
abstract: BACKGROUND
  An acute subdural hematoma (aSDH) is a rare complication of aneurysmal subarachnoid hemorrhage (SAH) and is associated with poor clinical condition on admission and poor outcome. Risk factors for the development of an aSDH from aneurysmal rupture are unknown and may help our understanding of how an aSDH develops.
  
  
  OBJECTIVE
  To identify risk factors for the development of an aSDH from intracranial aneurysm rupture.
  
  
  METHODS
  Patients were selected from our prospectively collected single-center SAH database. From all 1757 patients fulfilling prespecified inclusion criteria, 63 had an aSDH. We assessed sex, age, smoking, hypertension, history of SAH, sentinel headache, location of the ruptured aneurysm, and intracerebral hemorrhage (ICH) as risk factors for an aSDH. Univariable and multivariable risk ratios with corresponding 95% confidence intervals (CIs) were calculated for characteristics with Poisson regression.
  
  
  RESULTS
  Multivariable risk ratios were 1.021 (95% CI: 1.001-1.042) for each year increase in age, 2.3 (95% CI: 1.3-3.8) for posterior communicating artery aneurysms, 3.0 (95% CI: 1.5-6.0) for sentinel headache, and 5.2 (95% CI: 3.1-8.9) for ICH. None of the 95 patients (0%; 95% CI: 0%-3.8%) with a ruptured vertebrobasilar aneurysm had an aSDH, which was statistically significantly lower than at other sites (P = .02 for basilar aneurysm; P = .04 for vertebral aneurysm). None of the other studied characteristics had a statistically significant association with an aSDH.
  
  
  CONCLUSIONS
  Increasing age, sentinel headache, ICH, and aneurysms at the posterior communicating artery are independent risk factors for an aSDH. Patients with a basilar or vertebral aneurysm have a low risk of an aSDH.
authors.affiliation: Department of Neurology and Neurosurgery, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, The Netherlands. J.M.Biesbroek@umcutrecht.nl
authors.forename: J Matthijs
authors.initials: JM
authors.lastname: Biesbroek
authors.forename: Gabriel J E
authors.initials: GJ
authors.lastname: Rinkel
authors.forename: Ale
authors.initials: A
authors.lastname: Algra
authors.forename: Jan Willem Berkelbach
authors.initials: JW
authors.lastname: van der Sprenkel
mesh_terms: D017542:Aneurysm, Ruptured / Q000401:mortality* / Q000601:surgery*; D015897:Comorbidity; D005260:Female; D020199:Hematoma, Subdural, Acute / Q000401:mortality*; D006801:Humans; D002532:Intracranial Aneurysm / Q000401:mortality* / Q000601:surgery*; D008297:Male; D009426:Netherlands / Q000453:epidemiology; D015995:Prevalence; D016016:Proportional Hazards Models; D012307:Risk Factors; D016019:Survival Analysis; D015996:Survival Rate; D016896:Treatment Outcome