Cortical Excitability, Perseveration, and Stuttering

Abstract

Twenty-three male stutterers were compared with 25 male nonstutterers on measures of speech behavior, perseveration, and neurologic function. Flicker fusion threshold was determined as the single measure of perseveration, and multiple oral readings of a 218-word passage were recorded. Stuttering frequency for all subjects was computed from the tapes and, for the stuttering subjects, measures of adaptation and consistency were derived. Routine resting EEG records were obtained, and recording was continued during sleep, hyperventilation, intermittent photic stimulation, and two episodes of oral reading, one before and one immediately after hyperventilation. Abnormal or borderline EEGs were observed in 48% of the stutterers, as compared with 12% of the nonstutterers. Stutterers also exhibited a significantly greater cortical sensitivity to hyperventilation, regardless of age. This was true even of those with normal EEGs. Hyperventilation also appeared to reduce stuttering frequency among stutterers with anomalous EEGs. With respect to stuttering frequency, adaptation, and consistency, stutterers with anomalous EEGs did not differ significantly from those with normal EEGs. Mean flicker fusion threshold was significantly lower in the stuttering group. Stutterers with anomalous EEGs had higher fusion thresholds than those with normal EEGs. Flicker fusion threshold appeared to be unrelated to stuttering frequency, adaptation, and consistency.