Transcranial Ultrasound - Page 4

What are the risks of the test?

The transcranial Doppler ultrasound test is safe and painless because it uses harmless sound waves, not radiation, to produce the image. A compression test, although rarely done, can be risky for people with narrowed carotid arteries because the pressure placed on the arteries can cause a piece of plaque to break off.

Is transcranial Doppler ultrasound better than other tests for predicting my risk of another stroke?

Unlike ultrasound used to look at the carotid arteries in the neck, the sound waves used in transcranial Doppler ultrasound are partially blocked by the skull, limiting the accuracy of the test. The device is placed over parts of the skull where the bone is thin, but this limits the angles at which the blood vessels can be viewed. In some people, the bone is too thick for sound waves to pass all the way into the brain; this problem is especially common in older women.⁸

A major advantage of transcranial Doppler ultrasound is that it can be used continuously and safely to monitor blood flow patterns inside the brain after a stroke.It is also faster and less expensive than other tests, such as MRA, CTA, and angiography. Unlike these other tests, there is no need to inject a dye into your blood vessels during the ultrasound test.

The pictures produced by transcranial Doppler ultrasound are not as detailed as those from other tests. However, it is sensitive enough to rule out more invasive tests when no blockages or narrowing are detected.⁷ Abnormal results from the transcranial Doppler ultrasound usually need to be confirmed with another test before making any treatment decisions.⁷

References

1. Bedell E.A., Prough DS. Cerebral Blood Flow Monitoring. In: Irwin RS RJ, ed. Irwin and Rippe's Intensive Care Medicine. 6 ed. Philadelphia: Lippincott Williams & Wilkins; 2008.
2. Sloan MA, Alexandrov AV, Tegeler CH, et al. Assessment: Transcranial Doppler ultrasonography: Report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology. Neurology. May 11, 2004;62(9):1468-1481.
3. Oyama K, Criddle L. Vasospasm After Aneurysmal Subarachnoid Hemorrhage. Crit Care Nurse. October 1, 2004;24(5):58-67.
4. Ackerstaff RGA, Moons KGM, van de Vlasakker CJW, et al. Association of Intraoperative Transcranial Doppler Monitoring Variables With Stroke From Carotid Endarterectomy. Stroke. August 1, 2000;31(8):1817-1823.
5. Ackerstaff RG. Cerebral circulation monitoring in carotid endarterectomy and carotid artery stenting. Front Neurol Neurosci. 2006;21:229-238.
6. Baracchini C, Manara R, Ermani M, Meneghetti G. The Quest for Early Predictors of Stroke Evolution : Can TCD Be a Guiding Light? Stroke. December 1, 2000;31(12):2942-2947.
7. Feldmann E, Wilterdink JL, Kosinski A, et al. The Stroke Outcomes and Neuroimaging of Intracranial Atherosclerosis (SONIA) Trial. Neurology. June 12, 2007;68(24):2099-2106.
8. Wijnhoud AD, Franckena M, van der Lugt A, Koudstaal PJ, Dippel ED. Inadequate Acoustical Temporal Bone Window in Patients With a Transient Ischemic Attack or Minor Stroke: Role of Skull Thickness and Bone Density. Ultrasound Med Biol. Feb 1 2008.