title: Basilar artery vasospasm and delayed posterior circulation ischemia after aneurysmal subarachnoid hemorrhage.
abstract: OBJECTIVE
  The clinical and hemodynamic impacts of basilar artery (BA) vasospasm (VS) after aneurysmal subarachnoid hemorrhage (SAH) are ill-defined. The purpose of the present study was to evaluate the relationship between BA-VS and regional cerebral blood flow (rCBF) with posterior circulation after aneurysmal SAH.
  
  
  METHODS
  Daily transcranial Doppler (TCD) measurements of posterior and anterior circulation arteries were conducted in 162 patients with aneurysmal SAH. rCBF to the brain stem (BS) and other brain territories was assessed by multiple single-photon emission computed tomography with (99m)Tc ethyl cysteinate dimer single-photon emission computed tomography (ECD-SPECT) imaging during the course of VS.
  
  
  RESULTS
  SPECT imaging showed delayed BS hypoperfusion in 29 patients (17.9%). Of them, 23 patients (79.3%) were found to have BA-VS. Patients with very high BA flow velocities (FVs; >115 cm/s) had a 50% chance of developing delayed BS ischemia. BA-VS was found at a higher rate in patients who experienced reduced rCBF in the cerebellum (56.3%), thalamic nuclei (68.4%), and occipital lobe (81.8%). Although patients with delayed BS hypoperfusion did not present with a higher clinical grade, their clinical outcome was significantly worse (Glasgow Outcome Score after 30 days 2.48+/-1.16 versus 3.3+/-1.27; P=0.001).
  
  
  CONCLUSIONS
  These findings suggest for the first time that BA-VS after aneurysmal SAH is associated with hypoperfusion to BS and other posterior circulation territories. The risk for delayed BS ischemia increased significantly when TCD BA-FVs were >115 cm/s.
authors.affiliation: Department of Neurological Surgery, Harborview Medical Center, University of Washington, Seattle, Washington, USA. sviri@u.washington.edu
authors.forename: Gill E
authors.initials: GE
authors.lastname: Sviri
authors.forename: David H
authors.initials: DH
authors.lastname: Lewis
authors.forename: Reinaldo
authors.initials: R
authors.lastname: Correa
authors.forename: Gavin W
authors.initials: GW
authors.lastname: Britz
authors.forename: Colleen M
authors.initials: CM
authors.lastname: Douville
authors.forename: David W
authors.initials: DW
authors.lastname: Newell
mesh_terms: D000328:Adult; D000368:Aged; D001488:Basilar Artery; D020520:Brain Infarction / Q000209:etiology*; D020526:Brain Stem Infarctions / Q000209:etiology*; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012039:Regional Blood Flow; D012306:Risk; D013345:Subarachnoid Hemorrhage / Q000150:complications* / Q000175:diagnosis; D015899:Tomography, Emission-Computed, Single-Photon; D017585:Ultrasonography, Doppler, Transcranial; D020301:Vasospasm, Intracranial / Q000209:etiology*