Evaluation of posterior cerebral artery blood flow with transcranial Doppler sonography: Value and risk of common carotid artery compression

Purpose. Investigations of the posterior cerebral arteries (PCA) by transcr anial 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 TC D studies and assessed retrospectively its risks and prospectively its bene fits for PCA evaluations. Methods. Using the transtemporal approach, we prospectively assessed flow v elocities in posteriorly located blood vessels in 180 consecutive patients before and during CCA compression. The complications of CCA compression wer e retrospectively reviewed in all 3,383 clinical TCD investigations perform ed over an 8-year period. Results. Decreased flow velocities during ipsilateral CCA compression occur red in 17% of patients. A PCA-like vessel with perfusion from the carotid a rtery or PCA supply from the carotid circulation was unmasked. Mixed distal PCA support by the posterior communicating artery and proximal PCA could n ot 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 o f the PCA. Since transient cerebral symptoms during CCA compression are rar e, CCA compression can be used when a clinical TCD investigation of intracr anial collateral blood flow compensation is indicated or when the identific ation of a cerebral artery is uncertain. (C) 2000 John Wiley & Sons, Inc.