Stimulus rate-induced VEP attenuation in preterm infants.

The effect of the stimulus rate on the single flash VEP amplitude and latency (N1) was studied in 26 mechanically ventilated, preterm infants during the first days of life. Significant decreases in VEP amplitude and increases in latency were observed within a series of 3 single flash VEPs recorded with stimulus rates of 1/4 Hz. After a recovery period of 30 sec between series, the amplitude had attained baseline level, whereas the latency delayed progressively. The underlying cause of this rate effect is speculative, as individual degrees of VEP attenuation were not statistically related to gestational age, clinical state or cerebral oxygen delivery.