Background: Arterial flow velocity changes on transcranial Doppler can reflect changes in cerebral flow during position-induced ischemia if obtained during short-term monitoring of positional changes. Subjects and Methods: Our multicenter group monitored symptomatic and asymptomatic arteries in patients with recurrent neurological deficits during positional changes and documented intracranial arterial stenosis. Bilateral posterior cerebral and middle cerebral arteries were monitored dependent on clinical symptom localization. The symptomatic artery was monitored distal to the intracranial stenosis, and mean flow velocities (MFV) were recorded at different body positions. The symptomatic artery relative MFV ratio was defined as the ratio of symptomatic artery MFV in the asymptomatic position – MFV in the symptomatic position/MFV in the asymptomatic position. Results: Sixteen patients underwent transcranial Doppler monitoring: mean age 62 ± 19 years, 11 (69%) men, 6 (40%) with transient ischemic attacks. Ten patients (63%) had posterior and 6 anterior circulation symptoms. Patients developed neurological symptoms while standing up (63%) and/or sitting (44%), walking (13%) or during neck extension (6%). Symptomatic artery MFV dropped by ≧25% from the resting to the symptomatic position in all patients except for one. The mean symptomatic artery MFV relative ratio was higher compared with the mean asymptomatic artery MFV relative ratio: 0.5 ± 0.28 versus –0.02 ± 0.1 (p = 0.001, Wilcoxon test). The symptomatic artery relative ratio of >0.25 had a 94% sensitivity and 100% specificity for predicting neurological symptom development during testing (ĸ = 0.9, p < 0.001). Conclusions: A significant reduction in intracranial flow velocity distal to an intracranial stenosis can identify patients whose symptoms can worsen with positional changes. These patients may prove a target for interventional revascularization techniques.

Keywords:
Intracranial arterial stenosis, Arterial flow velocity, Hypoperfusion
1.
Warlow CP, Morris PJ: Transient Ischemic Attacks. New York , Marcel Dekker, 1982.
2.
Ruff RL, Talman WT, Petito F: Transient ischemic attacks associated with hypotension in hypertensive patients with carotid artery stenosis. Stroke 1981;12:353–355.
3.
Caplan LR, Wong KS, Gao S, Hennerici MG: Is hypoperfusion an important cause of strokes? If so, how? Cerebrovasc Dis 2006;21:145–153.
4.
Somerville ER: Orthostatic transient ischemic attacks: a symptom of large vessel occlusion. Stroke 1984;15:1066–1067.
5.
Pascual-Leone A, Anderson DC, Larson DA: Volume therapy in orthostatic transient ischemic attacks. Stroke 1989;20:1267–1270.
6.
Baquis GD, Pessin MS, Scott RM: Limb shaking – a carotid TIA. Stroke 1985;16:444–448.
7.
Tatemichi TK, Young WL, Prohovnik I, Gitelman DR, Correll JW, Mohr JP: Perfusion insufficiency in limb-shaking transient ischemic attacks. Stroke 1990;21:341–347.
8.
Alexandrov AV, Sharma VK, Lao AY, Tsivgoulis G, Malkoff MD, Alexandrov AW: Reversed Robin Hood syndrome in acute ischemic stroke patients. Stroke 2007;38:3045–3048.
9.
Nguyen-Huynh MN, Wintermark M, English J, Lam J, Vittinghoff E, Smith WS, Johnston SC: How accurate is CT angiography in evaluating intracranial atherosclerotic disease? Stroke 2008;39:1184–1188.
10.
Feldmann E, Wilterdink JL, Kosinski A, Lynn M, Chimowitz MI, Sarafin J, Smith HH, Nichols F, Rogg J, Cloft HJ, Wechsler L, Saver J, Levine SR, Tegeler C, Adams R, Sloan M, The Stroke Outcomes and Neuroimaging of Intracranial Atherosclerosis (SONIA) Trial Investigators: The Stroke Outcomes and Neuroimaging of Intracranial Atherosclerosis (SONIA) trial. Neurology 2007;68:2099–2106.
11.
Newell DW, Aaslid R: Transcranial Doppler: clinical and experimental uses. Cerebrovasc Brain Metab Rev 1992:4:122–143.
12.
Caplan LR, Wityk RJ, Glass TA, Tapia J, Pazdera L, Chang HM, Teal P, Dashe JF, Chaves CJ, Breen JC, Vemmos K, Amarenco P, Tettenborn B, Leary M, Estol C, Dewitt LD, Pessin MS: New England Medical Center Posterior Circulation registry. Ann Neurol 2004;56:389–398.
13.
Tatemichi TK, Young WL, Prohovnik I, Gitelman DR, Correll JW, Mohr JP: Perfusion insufficiency in limb-shaking transient ischemic attacks. Stroke 1990;21:341–347.
14.
Jiang W, Gao F, Du B, Srivastava T, Wang Y: Limb-shaking transient ischemic attack induced by middle cerebral artery stenosis. Cerebrovasc Dis 2006;21:421–422.
15.
Dobkin BH: Orthostatic hypotension as a risk factor for symptomatic occlusive cerebrovascular disease. Neurology 1989;39:30–34.
16.
Khan A, Beletsky V, Kelley R, Ehsan T: Orthostatic-mediated hypoperfusion in limb-shaking transient ischemic attack. J Neuroimaging 1999;9:43–44.
17.
Yonas H, Pindzola RR: Physiological determination of cerebrovascular reserves and its use in clinical management. Cerebrovasc Brain Metab Rev 1994;6:325–340.
18.
Yonas H, Smith HA, Durham SR, Pentheny SL, Johnson DW: Increased stroke risk predicted by compromised cerebral blood flow reactivity. J Neurosurg 1993;79:483–489.
19.
Schneider P, Rossman M, Bernstein E, Torem S, Ringelstein E, Otis S: Effect of internal carotid artery occlusion on intracranial hemodynamics: transcranial Doppler evaluation and clinical correlation. Stroke 1988;19:589–593.
20.
Martí-Fàbregas JA, Catafau AM, Marí C, Mendoza G, Sanahuja J, Lleó A, Martí-Vilalta JL: Cerebral perfusion and haemodynamics measured by SPET in symptom-free patients with transient ischaemic attack: clinical implications. Eur J Nucl Med 2001;28:1828–1835.
21.
Newell DW, Aaslid R, lam A, Mayberg TS, Winn HR: Comparison of flow and velocity during dynamic auto-regulation in humans. Stroke 1994;25:793–797.
© 2010 S. Karger AG, Basel
2010
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.