P.247Capturing disease progression in oculopharyngeal muscular dystrophy (OPMD)

Abstract

Oculopharyngeal muscular dystrophy is a rare late onset progressive neuromuscular disorder, characterized by ptosis, dysphagia and muscle weakness in upper and lower extremities. Little is known about the progression of the disease. The objective of this study is to describe the natural history of OPMD using clinical measurements and to identify the most sensitive clinical outcome measure for capturing disease progression. Forty-five genetically confirmed OPMD patients were examined twice at 18 months apart. The study protocol included measurements of muscle strength (maximum isometric tongue pressure, maximum bite force, MRC grading of muscles of the extremities, dynamometry of iliopsoas, quadriceps and deltoid muscles), and functional capacity tests (Motor Function Measure (MFM), 10-step stair test, maximum chewing time, maximum swallowing speed, maximum swallowing volume, maximum phonation time). There was a significant difference between the first and second examination for tongue pressure (p=.000), MRC sumscore (p=.003), dynamometry of the iliopsoas, quadriceps and deltoid muscle (p=.029, p=.002, p=.000), part 1 of the MFM on standing and transfer tasks (p=.004), and the 10-step stair test (p=.001). None of the other measures showed a significant change over 18 months. Despite slow disease progression of OPMD, this study is the first to show a significant progression in several clinical outcome measures over a period of 18 months. Muscle strength by MRC-grading and dynamometry, tongue pressure and part 1 of the MFM, rather than functional capacity tests, are sensitive measures for disease progression and thus potentially useful as clinical outcome measures fur future clinical trials.