Effect of delayed intermittent ventricular drainage on ventriculomegaly and neurological deficits in experimental neonatal hydrocephalus.

PURPOSE: Evidence-based guidelines do not indicate when ventricular reservoirs should be placed in children with neonatal hydrocephalus, and delayed intervention is common. We hypothesize that delayed ventricular drainage has adverse effects on structural development and functional outcomes.
METHODS: Using a well-established animal model of kaolin-induced obstructive hydrocephalus, we evaluated neurologic deficit after early (~1 week post-kaolin) or late (~2 weeks post-kaolin) placement of ventricular reservoirs which were tapped according to strict neurologic criteria.
RESULTS: Progressive ventriculomegaly was similar in early- and late-reservoir implantation groups. The average neurologic deficit scores (NDSs) over the experimental period were 0 (n=6), 2.74 (n=5), and 2.01 (n=3) for the control, early-, and late-reservoir groups, respectively. At reservoir placement, early-group animals displayed enlarged ventricles without neurologic deficits (mean NDS=0.17), while the late group displayed ventriculomegaly with clinical signs of hydrocephalus (mean NDS=3.13). The correlation between ventriculomegaly severity and NDS in the early group was strongly positive in the acute (before surgery to 3 weeks post-reservoir placement) (R(2)=0.65) and chronic (6 to 12 weeks post-reservoir placement) (R(2)=0.65) phases, while the late group was less correlated (acute R(2)=0.51; chronic R(2)=0.19).
CONCLUSIONS: Current practice favors delaying reservoir implantation until signs of elevated intracranial pressure and neurologic deficit appear. Our results demonstrate that animals in early and late groups undergo the same course of ventriculomegaly. The findings also show that tapping reservoirs in these neonatal hydrocephalic animals based on neurologic deficit does not halt progressive ventricular enlargement and that neurologic deficit correlates strongly with ventricular enlargement.