Transcranial Doppler in serious malaria

Introduction

Many assumptions have been proposed to explain the confinement of red blood cells infested by Plasmodium falciparum in the cerebral capillaries (cell adherence, rosetting), involving an increase in blood viscosity and a deceleration in blood flow inside capillaries.

Methods

In this study, 10 nonimmune adults were included with serious malaria according to the WHO classification. All of them had one or more criteria of gravity. A Quantitative Buffy Coat malaria test, a microscopic examination of thick and thin blood smear and transcranial Doppler were carried out from entry. We compared the transcranial Doppler findings, the pulsatility index (PI), with the degree of parasitemia. Data are expressed as the mean, standard deviation, extremes and percentage.

Results

The age of the patients was 40 ± 13 (SD) years (19–62). The sex ratio was 0.9. SAPS II was 34.3 ± 10 (SD) (20–53). The Glasgow Coma Scale score was 10 ± 4 (SD) (14–3). The parasitemia was 12.2 ± 16.9% (SD) (0.01–50). The PI (by averaging the two middle cerebral arteries' PI) was 1.9 ± 2.5 (0.8–9). The correlation coefficient between parasitemia and the PI was 0.86.

Conclusion

Some studies, carried out in children, demonstrated the interest in monitoring cerebral perfusion pressure and transcranial Doppler in prognostic evaluation of cerebral malaria [1]. In the adult, the interest in monitoring cerebral perfusion pressure was also demonstrated [2]. Nevertheless, measurement of intracranial pressure is related with hemorrhagic risk because of homeostasis disorder usually observed during serious malaria. We know there is no exact correlation between the degree of parasitemia and the quantity of red blood cells confined in cerebral capillaries. Nevertheless, in our preliminary study, there is a correlation between the degree of parasitemia and disturbance of the cerebral flow. Indeed, the PI rises when parasitemia increases.