Does age play a role in mylohyoideus muscle function?
Because swallowing disorders are frequent in the elderly, we assessed the relationship between age and mylohyoideus muscle contraction, which is an important component of the initial step in swallowing. In a prospective study, 120 subjects without any personal history of diseases associated with swallowing disorders underwent electromyographic recording (EMG) of mylohyoideus muscle activity. Four groups of equal size (n = 30) were defined according to age (< or = 50, 51-70, 71-85, >85 years). The frequency and duration of mylohyoideus muscle asynchronisms were compared among the four groups. The comparison of mylohyoideus muscle EMG among groups did not show a significant difference in the mean number of asynchronisms, in duration per subject or in the frequency of long-lasting asynchronisms. Asynchronisms were a very frequent event, observed in 98% of subjects, and were mostly short, lasting less than 0.1 s in 90% of subjects. In healthy elderly patients, there was no linear relationship between the mean duration of asynchronisms and ageing. The occurrence of one or more long-lasting asynchronisms or of at least six asynchronisms during a sequence of 10 successive swallows should be considered to be abnormal.