Objective: To investigate the frequency of transcranial Doppler (TCD) waveform blunting in patients with severe (80–99%) symptomatic or asymptomatic extracranial carotid artery stenosis. Background: Severe carotid artery stenosis has been identified as a risk factor for ischemic stroke. Blunted Doppler 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 consecutive patients (mean age 72.4 years, SD 9.0 years; 37% women; 46 clinically symptomatic, 68 asymptomatic) with 80–99% stenosis of the extracranial internal carotid artery (ICA), as determined by duplex sonography, were examined with TCD. Flow velocities, pulsatility index, and spectral waveforms of the MCA distal to the ICA stenosis were assessed blinded to the clinical status of the ICA: Doppler waveform blunting was defined as loss of the characteristic systolic peak. Odds ratios with 95% confidence intervals and χ2 statistics were used to describe the association between waveform blunting and the symptomatic status of the ICA stenosis. Results: Among symptomatic patients, 23 (50%) had completed strokes, and a further 23 (50%) had transient neurologic deficits in the territory of the stenotic ICA. Blunted spectral 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, 95% CI 3.1–18.1, p < 0.001). Conclusions: Our findings suggest that TCD waveform blunting in the MCA as here described may be an additional risk factor in the setting of severe extracranial carotid artery stenosis. A prospectively designed study to confirm our results seems warranted.

Keywords:
Transcranial Doppler, Pulsatility, Carotid stenosis
1.
North American Symptomatic Carotid Endarterectomy Trial Collaborators: Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis. N Engl J Med 1991;325:445–453.
2.
European Carotid Surgery Trialists’ Collaborative Group: MRC European Carotid Surgery Trial: Interim results for symptomatic patients with severe (70–99%) or with mild (0–29%) carotid stenosis. Lancet 1991;337:1235–1243.
3.
Executive Committee for the Asymptomatic Carotid Atherosclerosis Study: Endarterectomy for asymptomatic carotid artery stenosis. JAMA 1995;273:1421–1428.
4.
Masuhr F, Busch M, Einhäupl KM: Differences in medical and surgical therapy for stroke prevention between leading experts in North America and Western Europe. Stroke 1998;29:339-345.
5.
Warlow C: Endarterectomy for asymptomatic carotid stenosis? Lancet 1995;345:1254–1255.
6.
Kelley RE, Namon RA, Mantelle LL, Chang JY: Sensitivity and specificity of transcranial Doppler ultrasonography in the detection of high-grade carotid stenosis. Neurology 1993;43:1187–1191.
7.
Wilterdink JL, Feldmann E, Furie KL, Bragoni M, Benavides JG: Transcranial Doppler ultrasound battery reliably identifies severe internal carotid artery stenosis. Stroke 1997;28:133–136.
8.
Latino JM, Chleboun JO: The validity of Doppler-derived spectral analysis in the presence of multiple stenoses. Aust N Z J Surg 1994;64:338–344.
9.
Fürst H, Hartl WH, Jansen I, Fink B, Piepgras A, Lauterjung L, Schildberg FW: Pathophysiology of unilateral high-grade carotid artery stenosis: Evaluation of intracranial haemodynamics by analysis of velocity waveforms from the middle cerebral artery. Clin Sci 1992;83:357–366.
10.
Schneider PA, Rossman ME, Bernstein EF, Torem S, Ringelstein B, Otis SM: Effect of internal carotid artery occlusion on intracranial hemodynamics: Transcranial Doppler evaluation and clinical correlation. Stroke 1988;19:589–593.
11.
von Reutern GM, von Büdingen HJ: Intracranial Doppler sonography in the investigation of cerebrovascular stenoses and occlusions; in von Reutern GM, von Büdingen HJ (eds): Ultrasound Diagnosis of Cerebrovascular Disease. New York, Thieme, 1993, pp 281–288.
12.
Egido JA, Castrillo C, Sanchez M, Rabano J: Takaysu’s arteritis: Transcranial Doppler findings and follow-up. J Neurosurg 1996;40:121–124.
13.
Gymnopoulos C, Ramadan NM: Low pulsatility signals through the orbits. Stroke 1996;27:300–302.
14.
Zwiebel WJ: Analysis of carotid Doppler signals; in Zwiebel WJ (ed): Vascular Ultrasonography, ed 2. Philadelphia, Saunders, 1986, pp 171-216.
15.
Howard G, Chambless LE, Baker WH, Ricotta JJ, Jones AM, O’Leary D, Howard VJ, Elliott TJ, Lefkowitz DS, Toole JF: A multicenter validation study of Doppler ultrasound versus angiography. J Stroke Cerebrovasc Dis 1991;1:166–173.
16.
Fleiss JL: Statistical Methods for Rates and Proportions, ed 2. Chichester, Wiley, 1981.
17.
Hanlo PW, Peters RJ, Gooskens RH, Heethaar RM, Keunen RW, van Huffelen AC, Tulleken CA, Willemse J: Monitoring intracranial dynamics by transcranial Doppler – a new Doppler index: Trans systolic time. Ultrasound Med Biol 1995;21:613–621.
18.
Hartl WH, Fürst H: Application of transcranial Doppler sonography to evaluate cerebral hemodynamics in carotid artery disease: Comparative analysis of different hemodynamic variables. Stroke 1995;26:2293–2297.
© 2000 S. Karger AG, Basel
2000
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.