Usefulness of multifocal VEP in a child requiring perimetry.

We examined the reliability of multifocal visual evoked potentials for evaluating visual-field defects in a child with epilepsy and an arachnoid cyst. Multifocal visual evoked potentials were measured both when perimetry was difficult and several years later, when kinetic perimetry became possible in a child with epilepsy and homonymous hemianopia, as suggested by computed tomography of the brain. The peak latency and amplitude of response waves were used for assessment. The recordings of multifocal visual evoked potentials at both times revealed marked decreases in amplitude in the left visual hemifield. This area of decreased amplitude corresponded to the location of the lesion observed with imaging techniques, and was consistent with the left homonymous hemianopia observed via kinetic perimetry. The objective evaluation of visual-field defects through multifocal visual evoked potentials may be useful in children in whom conventional perimetry is difficult.