Functional transcranial Doppler

Transcranial Doppler is an ultrasonic technique, which demonstrates the blood flow velocity in the intracranial arteries. Functional Transcranial Doppler (fTCD) is a method of comparing the cerebral blood flow velocities of different arteries demonstrated simultaneously in both hemispheres. The examination is performed before and after fulfilling certain motor and sensory functions and execution of cognitive tasks. The rationale behind this method is discussed as it is applied in each of those functions. It must be stressed that there is a different role of the fTCD in the anterior vs the posterior circulation systems. Whereas many studies prove good efficacy with use of middle cerebral artery and anterior cerebral artery method, the role of the vertebrobasilar system method is unclear. In addition, although visual functions can be demonstrated well by examination of the posterior cerebral arteries, only few evidences of efficacy were published concerning vertebral and basilar artery functions. However, fTCD is useful, easy to perform and presents a very cost effective method for demonstration of cerebral blood flow changes during and after completing cognitive and motor tasks. The tests can be used in healthy persons, as well as in patients with neurological diseases and during rehabilitation period.