Transcranial Doppler (TCD) Ultrasound as a Noninvasive Means of Monitoring Cerebrohaemodynamic Change in Hydrocephalus

Abstract

Cerebral blood flow velocity (CBFV) measurements by Transcranial Doppler (TCD) ultrasound were performed on 27 patients with hydrocephalus (Group I: neonates, Group II: children). Simultaneous measurements of direct ICP and CBFV were performed during ventricular taps in 16 patients. There was a significant correlation between ICP and Resistance Index (RI = peak systolic-end diastolic/peak systolic velocity) overall in Group II patients (p < 0.02) and in individual neonatal patients (p < 0.001). After ventricular taps and ventriculo-peritoneal shunting (17 patients) there was a consistent significant decrease in RI due to increased end diastolic velocity in all patients (p < 0.001). This suggests the RI is a reliable index of cerebrovascular resistance for serial monitoring in individual patients. There was an exponential pattern of decay in RI with CSF volume depletion (volume-flow velocity response) in 50/56 taps which allows calculation of a volume-buffering reserve before perfusion change occurred. Simultaneous ICP/CBFV monitoring during sleep may help to identify patients who are unable to compensate haemodynamically during episodic increase in ICP and are a greater risk of ischaemic insult. TCD is a useful noninvasive technique of monitoring cerebrohaemodynamic change for initial assessment and further management of children with hydrocephalus.

Key words

Transcranial Doppler ultrasound - Hydrocephalus - Resistance Index