A Volume-Blood Flow Velocity Response (VFR) Relationship Derived from CSF Compartment Challenge as an Index of Progression of Infantile Hydrocephalus

Abstract

Optimal management in childhood hydrocephalus requires prevention of secondary ischemic damage and reliable indication for surgical treatment to prevent long-term shunt related complications. Transcranial Doppler ultrasound provides a noninvasive means of monitoring cerebrohemodynamic response. Cerebral blood flow velocity (CBFV) and intracranial pressure (ICP) was measured during 38 CSF taps in 11 patients (6 neonates, 5 children). the Resistance Index (RI = S - D/S) (where S - peak systolic velocity and D - end diastolic velocity) decreased significantly (P< .001) after all taps, mainly due to a larger percentage increase in diastolic velocity and mean flow velocity (MFV) which increased in 89% of taps, suggesting a significant reduction in cerebrovascular resistance and increased flow after cerebrospinal fluid (CSF) depletion. There was significant positive correlation of RI to ICP (r = 0.63, P < .001) in older children. Exponential decay of RI with volume depletion allows estimation of "critical" volume buffering capacity. Serial volume flow velocity response (VFR) in individual infants may indicate progression or arrest of the hydrocephalic process and may help to select more precisely those who will benefit from surgical intervention.