Normal Cerebral Blood Flow Volume in Healthy Nigerian Adults

Background: Blood supply to the brain is very vital for its functions. Most of the pathologic processes that affect the acutely injured brain eventually results in impairment of cerebral blood flow (CBF). Early identification of the ischaemic or hyperemic conditions is critical to define the most appropriate therapeutic strategies. However, there is paucity of data on the normal cerebral blood volume in Sub Saharan Africa; we therefore employed the use of a safe, practical, economical, repeatable and readily available Doppler ultrasonography to evaluate CBF.

Aims and Objectives: The main aim of the study was to determine age and sex specific normal cerebral blood flow volume by Doppler ultrasonography of the extracranial carotid and vertebral arteries in healthy Nigerian adults.

Methodology: Three hundred and ninety six (396) subjects that met the inclusion criteria were examined with the aid of Doppler ultrasound machine. All the subjects were scanned by the same radiologist, thereby avoiding inter observer variability and each measurement was taken thrice and an average found. The flowmetry values from the carotid and vertebral arteries were statistically analyzed using SPSS version 16.

Results: The total cerebral blood flow volume was 624.90±115.57 ml/min with the mean blood flow volumes of 226.57±32.03 ml/min and 226.85±31.58 ml/min (right and left internal carotid arteries); 85.59±27.81 ml/min, and 85.59±27.20 ml/min (right and left vertebral arteries). The mean total cerebral blood flow volume was more in the males (625.64±116.38 ml/min) than the females (624.75±115.06 ml/min), decreasing with increasing age in both sexes with associated increase in vessels diameters with age. Although, statistically significant differences (P<0.001) were seen in the Peak.

Systolic velocities (PSV), End diastolic velocities (EDV) and Resistive Indexes (RI) of the internal carotid arteries in Males and Females, the difference in the total cerebral blood volume was not significant. The intra rater reliability showed an almost perfect agreement with an average Kappa coefficient of 0.88.

Conclusion: Our study has provided a safe, economical and repeatable age, sex and side specific extracranial normogram of flowmetries of individual and total cerebral blood vascular supplies to the brain which is essential in successful management of cerebrovascular diseases.