Tongue strength and clinical correlations in Parkinson's disease

Individuals with Parkinson's disease present affected lingual functioning at some stage of the progression of the disease. The objective was to determine the strength and endurance values of the tongue in PD subjects and whether weakness in tongue lift may be an indicator of disease progression.

To determine the strength and endurance values of the tongue in PD subjects and whether weakness in tongue lift may be an indicator of disease progression.

Sixty subjects performed tasks of tongue to palate maximum isometric pressure (MIP) and sustained 50% of MIP for endurance. The Iowa Oral Performance Instrument was used as evaluation tool. Selected domains of the Swallowing Quality of Life Questionnaire (SWAL-QOL) related to tongue pressure were considered. Variables of sex, age, disease duration, disease progression (Hoehn & Yahr stage) and body mass index were selected for association analysis.

Tongue MIP ranged from 16 to 48 kPa (mean = 33.43 kPa), which was significantly lower than normal reference values. Likewise, tongue endurance was significantly diminished. Analysis of variance showed differences in tongue strength between stages of disease progression F(3) = 6.503, p = .001, but not for endurance. Subjects in stage IV exhibited the lowest values. No sex effect was found. Tongue strength showed significant correlations with SWAL-QOL domains such as food selection, symptoms frequency and eating duration.

Tongue strength and endurance are significantly reduced in Parkinson's disease. Tongue strength is higher in the early stage of the disease and significantly different from that of more severe stages, emerging the notion that tongue strength is a sensitive indicator of disease progression. Selected items regarding swallowing quality of life are strongly associated with tongue strength.