Objective: To describe anterior and posterior tongue elevation strength in participants with PSP

Background: It is widely recognized that the tongue plays a critical role in deglutition and speech. In addition to a rich literature defining the range of tongue strength in healthy young and older adults, several studies of neurologic populations have provided evidence for reduced tongue strength associated with dysarthria and dysphagia. Whereas tongue weakness is a hallmark feature in bulbar ALS, tongue strength is typically normal in PD.  No studies to date have reported tongue strength in a cohort of speakers with PSP.

Methods: As one component of a larger NIH-funded study examining tau imaging in PSP, participants (N=17) underwent speech and swallowing assessment, including objective measurement of anterior and posterior elevation strength. [table1] Analyses included descriptive statistics and correlation with dysphagia and dysarthria severity.

Results: Mean anterior tongue elevation strength for patients with PSP was 36.47 kPa (SD 12.8); posterior elevation strength 25 kPa (SD 8.9).  Both performance measures fall below one SD of the mean for healthy speakers over age 60. Whereas 6 participants had anterior strength that fell in the normal range, only 2 participants had posterior elevation strength in the normal range [figure1]. Anterior and posterior tongue strength correlated moderately with dysarthria severity, a finding that is inconsistent with most previous reports.  Tongue strength did not correlate strongly with dysphagia severity [table2].  

Conclusions: Tongue weakness was common in a cohort of patients with PSP.  This feature may distinguish PSP from hypokinetic dysarthria generally and PD more specifically. In this cohort with relatively mild bulbar signs, moderate association was observed between severity of weakness and severity of dysarthria. Tongue weakness was not associated with dysphagia severity, suggesting that even though tongue weakness may be present in PSP, other movement control impairments are limiting the effectiveness of the swallowing mechanism.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/tongue-strength-in-psp/