Speech fluency family profile--a linguistic, acoustic and electromyographic study.

Abstract

Background: genetic factors as a possible cause of stuttering.

Aim: to identify the speech fluency family profile (linguistic, electromyographic and acoustic aspects) in children with and without a close family history of stuttering.

Method: the study included a total of 127 individuals, 32 children (probands) and 95 members of the immediate family (father, mother, sisters and brothers). The individuals were divided in two groups: GI (SC) was composed of 17 probands with a diagnosis of stuttering, 17 fathers, 17 mothers, 10 brothers, and 13 sisters, and GII (NSC) was composed of 15 fluent probands, 15 fathers, 15 mothers, no brothers, and 8 sisters. All testing procedures were applied to all participants as follows: 1) identification of disruption typology; 2) electromyographic analyses; and 3) acoustic analyses.

Results: the percentage of affected mothers was 41.1%, and the percentage of affected fathers was 35.3%. In addition, the percentage of affected sisters was 6.7%, and 40% of the brothers were affected. Similarity was observed in the typology of speech disruptions in all of the affected individuals of the same family; however, a trend towards a greater severity of the disorder in probands was observed. Similarity was found in muscle activation for diadochokinesia rates in all the affected individuals in the same family. This suggests the existence of a speech motor pattern within the same family that can be measured by capturing peripheral muscle activation. Similarity was found in the acoustic variation for diadochokinetic rates in all affected individuals of the same family.

Conclusion: this study represents one of the first endophenotypic research proposals on stuttering characterized by two aspects: objective inclusion criteria and the type of stuttering symptomatology manifested.