Evoked potentials in infantile spasms.

In infants and toddlers (N = 8) with infantile spasms, visual and somatosensory evoked potentials (VEP, SEP) were recorded during the course of the illness. During hypsarrhythmia the pattern evoked potential was missing (7/8) or grossly abnormal (1/8), indicating functional amaurosis. Flash evoked responses were normal in 50% even during the EEG-status, showing the superiority of pattern versus flash evoked potentials for visual functions in infancy. The alterations were reversible after successful treatment. Early SEP-components remained normal even during the bioelectrical status but later cortical components were altered in a reversible manner. The results show the objective state of functional sensory block during the EEG-status and underline the necessity of quick and effective treatment to avoid delayed visual maturation.