Functional transcranial Doppler sonography

Functional transcranial Doppler sonography (fTCD) examines cerebral hemodyn amics at rest and during diverse activation manoeuvres. In the fTCD during visual activation the posterior cerebral artery (PCA) is insonoted. Further fTCD methods for the evaluation of the posterior circulation are the simul taneous insonation of the middle cerebral artery (MCA) and the PCA or direc t insonation of the basilar artery (BA) during vestibular stimulation using caloric irrigation. The fTCD during tilt-table-test with heed-up tilt is m eanwhile a very established method for autonomic testing. The fTCD during h ead-down tilt is still experimental for testing cerebrovascular autoregulat ion in healthy volunteers. The autoregulative stimulus is the rapid cephal blood influx which probably activates the myogenic mechanism of cerebrovasc ular autoregulation. The fTCD during ergometry examines cerebrovascular cha nges during physical stress. The cerebrovascular changes reflect the comple x coactivation of diverse autoregulative mechanisms (neurogenic, metabolic, myogenic). In patients with defined cerebrovascular disturbances (chronic tension type headache, migraine) abnormal findings were detected. FTCD is a new method which enables noninvasive and with exact time correlation chang es analysis of cerebrovascular hemodynamics during diverse activation proce dures. Clinical applications can be seen in patients with cerebrovascular o r autonomic diseases and in testing of cerebrovoscular autoregulation follo wing pharmocological treatment (e.g. antihypertensive drugs).