[Transcranial Doppler study of sylvian vascular reactivity as affected by a calcium inhibitor. Preliminary results apropos of 28 cases]

The transcranial Doppler 2 MHz test, a new non-invasive investigatory method, allows direct instantaneous recording from middle cerebral artery in 96% of healthy subjects and, in contrast to classical means of measuring cerebral blood flow, the possibility of continuous monitoring of middle cerebral artery in bedridden patients or during operation. This transcranial pulsed Doppler (T.P.D.) test was used to study the effect of a calcium inhibitor, Nifedipine, on middle cerebral artery smooth muscle and its cerebrovascular effects in 28 subjects: 8 cases of hypertension, 9 of sylvian artery stenosis confirmed by arteriography (5 approximately equal to 30% and 4 greater than or equal to 50%) and 11 healthy volunteers. Recording of middle cerebral artery flow by T.P.D. was preceded by cervicocephalic continuous emission Doppler exploration (DMS, MIRA 4 MHz) and vascular echotomography (Duplex Sonedap 10 MHz). Recordings from the first segment of middle cerebral artery were obtained from a low frequency (2 MHz) and high power (maximum 350 mW) probe introduced facing squamous portion of temporal bone. Identification of this artery is dependent on its depth of access--average 5 cm--its response to homolateral carotid artery compression and the convergence of its flux towards the probe. After sublingual absorption of 2 to 3 capsules of Nifedipine, systolic and diastolic blood pressure and systolic and diastolic frequencies of middle cerebral activity were recorded regularly over 20 minutes with the patient at rest in dorsal decubitus. Variations in these parameters were considered significant when 10% or more. Criteria proposed for identification of middle cerebral artery stenosis were segmental acceleration of 3 kHz or more with or without associated turbulence (fig. 2).(ABSTRACT TRUNCATED AT 250 WORDS)