title: Evaluation of posterior cerebral artery blood flow with transcranial Doppler sonography: value and risk of common carotid artery compression.
abstract: OBJECTIVE
  Investigations of the posterior cerebral arteries (PCA) by transcranial Doppler sonography (TCD) may be less reliable than investigations of the anterior part of the circle of Willis. Nevertheless, a true PCA may be identified by manual compression of the proximal common carotid artery (CCA) during TCD. Therefore, we used CCA compression in clinically indicated TCD studies and assessed retrospectively its risks and prospectively its benefits for PCA evaluations.
  
  
  METHODS
  Using the transtemporal approach, we prospectively assessed flow velocities in posteriorly located blood vessels in 180 consecutive patients before and during CCA compression. The complications of CCA compression were retrospectively reviewed in all 3,383 clinical TCD investigations performed over an 8-year period.
  
  
  RESULTS
  Decreased flow velocities during ipsilateral CCA compression occurred in 17% of patients. A PCA-like vessel with perfusion from the carotid artery or PCA supply from the carotid circulation was unmasked. Mixed distal PCA support by the posterior communicating artery and proximal PCA could not be shown by TCD. Transient cerebral symptoms occurred in less than 0.4% of the 3,383 retrospectively reviewed TCD investigations; no other adverse effects were seen.
  
  
  CONCLUSIONS
  TCD without CCA compression may lead to false identification of the PCA. Since transient cerebral symptoms during CCA compression are rare, CCA compression can be used when a clinical TCD investigation of intracranial collateral blood flow compensation is indicated or when the identification of a cerebral artery is uncertain.
authors.affiliation: Department of Neurology, Sahlgrenska University Hospital, S-4113 45 Göteborg, Sweden.
authors.forename: D
authors.initials: D
authors.lastname: Jatuzis
authors.forename: H
authors.initials: H
authors.lastname: Zachrisson
authors.forename: C
authors.initials: C
authors.lastname: Blomstrand
authors.forename: S
authors.initials: S
authors.lastname: Ekholm
authors.forename: J
authors.initials: J
authors.lastname: Holm
authors.forename: R
authors.initials: R
authors.lastname: Volkmann
mesh_terms: D001783:Blood Flow Velocity / Q000502:physiology; D002339:Carotid Arteries / Q000000981:diagnostic imaging; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging* / Q000502:physiology; D002536:Cerebral Arteries / Q000000981:diagnostic imaging / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D002941:Circle of Willis / Q000000981:diagnostic imaging / Q000502:physiology; D003097:Collateral Circulation / Q000502:physiology; D006801:Humans; D020769:Posterior Cerebral Artery / Q000000981:diagnostic imaging* / Q000502:physiology; D011312:Pressure; D011446:Prospective Studies; D012039:Regional Blood Flow / Q000502:physiology; D012189:Retrospective Studies; D018570:Risk Assessment; D013223:Statistics as Topic; D013701:Temporal Bone; D017585:Ultrasonography, Doppler, Transcranial / Q000009:adverse effects