Voice quality in down syndrome children treated with rapid maxillary expansion

Down syndrome (DS) is the most common aneuploid chromosomal disorder at birth. Phenotypic characteristics include mental retardation, general hypotonia, pharyngeal hypoplasia, frequently constricted maxillary arch with macroglossia and upper air way obstruction. Generally they have marked language difficulties and a characteristic voice. This prospective study assesses the effects of rapid maxillary expansion (RME) on voice quality in DS children. Acoustic (Praat-4.1 software) and perceptual assessment of the voice were performed in 24 children with DS, aged 4 to 12 years, who had been randomly allocated to RME and non-expanded (NE) groups. Two main evaluations were made; one prior to expansion and the second after two to four weeks of active RME plus a 5 month period of retention. Data between the two groups were compared. Perceptual analysis did not demonstrate any significant modification. RME produced significant changes in F1 frequency of vowel /a/ of DS children’s voices, probably related to alteration of vertical tongue adjustment. It also showed a tendency to decrease F0 dispersion in all studied vowels, illustrating increased stability in F0 production. These results are related to the correction of some DS typical mid-face skeletal deformities such as maxillary bone widening with improvement of upper airway airflow and increased space for the tongue in the oral cavity. The acoustic analysis is a simple, rapid and non-invasive technique which is well accepted by the paediatric population; features that are relevant to its application especially in children with mental retardation.