Collaborating researchers from various departments at Duke University, Durham, North Carolina, have found that tongue weakness and structural changes, such as atrophy, could hint at late-onset Pompe disease (LOPD) and help differentiate it from other acquired or hereditary causes of myopathy. The study findings could have considerable implications on the clinical approach to LOPD.
Late-onset Pompe disease (LOPD) is a debilitating glycogen storage disease caused by a deficiency of the enzyme acid alpha-glucosidase (GAA), which results in an accumulation of glycogen leading to skeletal, cardiac, and smooth muscle damage. Although treatment is available in the form of enzyme replacement therapy (ERT), diagnosis is often delayed due to the rarity of the disease, variability of clinical presentation, and overlap of signs and symptoms with other myopathies.
The study done at Duke included 70 participants, out of which 10 were recently diagnosed with LOPD, 30 had other forms of myopathy, and 30 had neuropathy and served as controls. Tongue strength was assessed using manual and quantitative muscle testing, while tongue structure was assessed using ultrasound, which evaluated characteristics such as overall appearance, echointensity, and thickness.
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The study noted statistically significant differences in tongue strength between people with LOPD and those with neuropathy. Quantitative muscle testing revealed statistically significant differences in tongue strength across the full sample, with LOPD patients demonstrating the lowest mean maximal lingual strength (37.4 kPa.) On ultrasound, participants with LOPD were also found to have the lowest tongue thickness, with statistically significant differences noted across the full sample.
The researchers acknowledge that inter-rater and blinded inter-rater reliability for qualitative tongue appearance in the study were poor, although inter-rater reliability for manual muscle testing was fair. They note that the study findings suggest that tongue involvement is often much more severe in LOPD patients than in other forms of myopathy. They also suggest that future studies should explore the effects of tongue involvement in LOPD on swallowing and speech.
Reference
Jones HN, Hobson-Webb LD, Kuchibhatla M, et al. Tongue weakness and atrophy differentiates late-onset Pompe disease from other forms of acquired/hereditary myopathy. Mol Genet Metab. 2021;133(3):261-268. doi:10.1016/j.ymgme.2021.05.005
