The reactivity of the cerebral vasculature, as assessed by the response in the middle cerebral artery blood velocity, measured by transcranial Doppler, to increases in arterial carbon dioxide, has been used to evaluate the haemodynamic effects of known extracranial carotid stenoses. We describe an additional use as a diagnostic clue to the presence of intracranial carotid stenoses in patients with normal extracranial carotid vessels. Two patients with carotid territory cerebrovascular events but angiographically normal extracranial carotid vessels were found to have markedly impaired carbon dioxide reactivity on the side of the symptomatic carotid artery but normal reactivity on the asymptomatic side. In view of this, selective carotid angiography was performed which showed a tight intracranial internal carotid stenosis in both cases.

Keywords:
Transcranial Doppler ultrasonography, Internal carotid artery, Transient ischaemic attack, Carotid artery disease
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© 1992 S. Karger AG, Basel
1992
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