Usefulness of Doppler method for evaluating intracranial hemodynamics in infantile hydrocephalus

The changes of pulsatility index (PI) were followed for anterior cerebral artery (ACA) and basilar artery (BA) in 8 hydrocephalic infants. PI increased with the progression of hydrocephalus in both ACA and BA, from an average of 0.69 to 0.80 and from 0.73 to 0.81, respectively. The index made a sharp dip in 6 hours 0.65 for ACA and 0.70 for BA after placing a V-P shunt. It eventually stabilized within mean +/- SE. (ACA:0.69 +/- 0.0042, BA:0.71 +/- 0.0036). The index enabled us to observe objectively cerebral vascular resistance of the illness in numerical values. It may become a useful tool for setting criteria for placing a shunt (about 0.80) as well as for judging the shunt effectiveness. Throughout the entire observation, changes in PI of both ACA and BA were well correlated. Anterior fontanel pressure was also correlated with PI in the period, except PI of BA before the shunt operation. However, the pre-shunt correlation of PI to lateral ventricle enlargement was lost after the shunt operation. And the ventricle size reduced only slightly when PI rapidly decreased in 6 hours after the V-P shunt. These facts indicated that the changes in PI was affected directly by the intracranial pressure rather than the enlarged ventricle. The findings of this study indicated the necessity of evaluating of the intracranial hemodynamics with other diagnostic approaches in managing infantile hydrocephalus.