Electrophysiological responses in hydranencephaly.

We recorded electrophysiological responses, both electroretinograms (ERGs) and visual evoked responses (VER), at 4 and 21 months of age in a child with hydranencephaly. As expected, the ERG was normal. Despite the apparent absence of most of the cerebral cortex, a VER was present at both visits. The child's visual performance definitely improved both subjectively and electrophysiologically. The VER contained multiple early components in contrast to previous reports, where only a slow, monophasic response was detected.