[Changes in the cerebral flow velocity induced in the middle cerebral artery by acute stress studied by transcranial Doppler ultrasonography].

Background: The behavior of brain flow on acute stress has not been previously evaluated. Transcranial Doppler ultrasonography (TD) is a bloodless method to evaluate the speed of cerebral flow in the arteries of the Willis polygon. The present study was designed to analyze the changes which occur in the same during two situations of acute stress.
Methods: The mean speed of cerebral flow (MS) and the pulsation rate (PR) of the right and left middle cerebral artery (MCA) were measured basally and following a mental stress test (calculation) and physical stress (cold test) by TD and through the temporal window. Twenty-five healthy volunteers (18 women and 8 men) with a mean age of 27.8 +/- 7.3 years were studied.
Results: In response to mental stress an increase was observed in MS in both the right MCA (10 +/- 8.6 cm/sec) and the left MCA (10.4 +/- 8.7 cm/sec) with a decrease in the MCA (0.14 +/- 0.23 in the right MCA, 0.14 +/- 0.18 cm/sec in the left MCA). In response to the cold test an increase in MS (7.3 +/- 7.5 cm/sec in the right MCA, 14.8 +/- 14.7 cm/sec in the left MCA) was also observed with a decrease in the PR (0.2 +/- 0.2 in the right MCA and 0.2 +/- 0.16 in the left MCA). No significant differences were observed in the changes induced in the right or left artery or in those induced by the mental or cold tests.
Conclusions: These results suggest that the acute stress produces an increase in cerebral flow in the arteries of the Willis polygon.