Transcranial Doppler sonography at the early stage of acute central nervous system infections in adults.

Transcranial Doppler sonography (TCD) of the middle, anterior and posterior cerebral arteries and of the basilar artery was used to evaluate the mean blood velocity (V mean) and the pulsatility index [PI = (V systolic-V diastolic)/V mean] as a vascular resistance index in 63 patients (male 40, female 23, mean age 43 +/- 19 y) with bacterial meningitis (n = 33, including 2 patients with fungal meningitis) and viral meningitis (n = 30) within 12 h after admission of the patients. The findings were similar for all intracranial arteries. Compared with reference values of 69 healthy volunteers [V mean of middle cerebral artery [MCA] 57 +/- 13 cm/s, MCA-PI 0.83 +/- 0.15], MCA-V mean was increased in patients with Glasgow coma scale (GCS) scores of 14 and 15 (71 +/- 18 cm/s; t-test: p < 0.001), not significantly different in the patients with GCS scores of 10-13 (55 +/- 21 cm/s) and decreased in those with GCS scores of 3-9 (42 +/- 21 cm/s, p < 0.01). The MCA-PI increased from 0.93 +/- 0.22 in the patients with GCS scores of 14-15 to 2.81 +/- 2.06 in those with GCS scores of 3-9 (p < 0.001 vs. controls). By regression analysis, MCA-V mean decreased and MCA-PI increased with decreasing GCS scores (p < 0.001). Only in patients with bacterial meningitis was the Glasgow outcome scale (GOS) score lower the more the MCA-PI was increased (regression analysis p < 0.001). We conclude that in patients with bacterial and viral meningitis, and in a good clinical state, the cerebral blood flow seems increased by hyperemia; with clinical deterioration the cerebral haemodynamics worsen. However, the early assessment of the cerebral blood flow by TCD seems useful for predicting outcome in bacterial meningitis only.