Transcranial Doppler waveform blunting in severe extracranial carotid artery stenosis

Objective: To investigate the frequency of transcranial Doppler (TCD) wavef orm blunting in patients with severe (80-99%) symptomatic or asymptomatic e xtracranial carotid artery stenosis. Background: Severe carotid artery sten osis has been identified as a risk factor for ischemic stroke. Blunted Dopp ler flow waveforms (reduced systolic flow velocity and pulsatility) of the middle cerebral artery (MCA) are inferred to reflect hemodynamic impairment , possibly indicating an increased risk of stroke. Methods: The 114 consecu tive patients (mean age 72.4 years, SD 9.0 years; 37% women; 46 clinically symptomatic, 68 asymptomatic) with 80-99% stenosis of the extracranial inte rnal carotid artery (ICA), as determined by duplex sonography, were examine d with TCD. Flow velocities, pulsatility index, and spectral waveforms of t he MCA distal to the ICA stenosis were assessed blinded to the clinical sta tus of the ICA: Doppler waveform blunting was defined as loss of the charac teristic systolic peak. Odds ratios with 95% confidence intervals and chi(2 ) statistics were used to describe the association between waveform bluntin g and the symptomatic status of the ICA stenosis. Results: Among symptomati c patients, 23 (50%) had completed strokes, and a further 23 (50%) had tran sient neurologic deficits in the territory of the stenotic ICA. Blunted spe ctral waveform was found in 37 (80%, 95% CI 68-92%) of the symptomatic and 25 (37%; 95% CI 25-49%) of the asymptomatic patients. Symptomatic patients had significantly increased odds of having blunted TCD waveforms (OR 7.5, 9 5% CI 3.1-18.1, p < 0.001). Conclusions: Our findings suggest that TCD wave form blunting in the MCA as here described may be an additional risk factor in the setting of severe extracranial carotid artery stenosis. A prospecti vely designed study to confirm our results seems warranted. Copyright (C) 2 000 S. Karger AG. Basel.