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ORCID
https://orcid.org/0000-0001-6198-8153
Date of Graduation
5-15-2025
Semester of Graduation
Spring
Degree Name
Doctor of Philosophy (PhD)
Department
Department of Communication Sciences and Disorders
First Advisor
Erin Kamarunas
Second Advisor
Christina Kuo
Third Advisor
Cynthia O'Donoghue
Fourth Advisor
Nicholas E Johnson
Abstract
Myotonic dystrophy type 1 (DM1) is a rare, progressive, autosomal dominant genetic neuromuscular disease affecting many bodily systems and results in reduced life expectancy. Muscular weakness is a classic symptom at all ages and affects the orofacial and oropharyngeal muscles in CDM and DM1 resulting in dysarthria and dysphagia. The impact of 1) motor speech differences on communication in CDM, and 2) orofacial sensation on swallowing function in DM1 are underexplored. This dissertation contains two distinct studies that examined these topics.
In the first study, the perceptual characteristics of speech during a repetition task of 22 children with CDM under 14 years of age were analyzed. Eight mean severity values were considered deviant across articulatory, resonant, prosodic, and rate features. Additionally, reduced intelligibility was quantified in four children during a reading task (range 22.5-62.7%). Two children showed improvement in intelligibility at 12 months, one had minimal improvement, and one demonstrated a decline.
In the second study, orofacial sensation and swallowing performance were quantified in 23 individuals with DM1 and 23 sex- and age-matched controls. Participant and clinician rating of swallow function and cognitive testing were also assessed. No sensory differences between groups were observed, however performance differences existed on aspects of water swallowing and cracker ingestion tasks. Regression modeling found sensory contributions predicting participant report of function (R2adj=.79), performance on water swallowing task (R2adj=.20), and clinician rating of function (R2adj=.69), along with other demographic characteristics.
Taken together, these studies present novel aspects of this disease across the lifespan. Children with CDM have reduced performance on speech tasks with rate and prosody being most affected. These correlate with intelligibility in other neurological diseases and may help begin to explain reduced intelligibility in CDM. Individuals with adult-onset DM1 demonstrated differences in swallow performance and oral sensation was found to be predictive of swallowing performance as well as patient- and clinician-rating of function.
Both dysarthria and dysphagia in DM1/CDM are likely multifactorial. Despite heterogeneity in the data for both studies, these results are novel and may suggest avenues of intervention to improve communication and swallowing safety and efficiency in this neurodegenerative disease.
