Visual evoked potentials in hydrocephalus: relationship to head size, shunting, and mental development.

Flash-evoked visual cortical potentials were measured in 54 infants and children with symptomatic hydrocephalus; 54 shunted, asymptomatic infants and children; and 57 controls. All patients were evaluated for head size, mental development, and history of infection of the nervous system. Hydrocephalic infants up to 60 weeks of conceptional age showed significant changes in the maturation curve of the latency to the main positive peak P2 (P100), particularly when their hydrocephalus was associated with an enlarged head or with infection. Older children of normal mental development presenting with acute hydrocephalus of recent onset had normal latencies to P2. Some persistent ventriculomegaly after shunting was also compatible with normal visual evoked potentials (VEPs). After shunting, the latency to P2 became normal in most of the patients who showed normal mental development, whereas retarded hydrocephalic children of all ages continued to have abnormal VEPs.