Functional evaluation and myotonometric measurements of muscle tone,stiffness and elasticity in patients with duchenne muscular dystrophy

Functional Evaluation and Myotonometric Measurements of Muscle Tone, Stiffness and Elasticity In Patients With Duchenne Muscular Dystrophy Aims: The aim of this study was to measure the biomechanical properties of the muscle using myotonometry in patients with Duchenne Muscular Dystrophy (DMD) and to evaluate the correlation with functional parameters. Material and Method: Thirty ambulatory DMD boys and 30 age matched healthy boys underwent measurements from their dominant sides. Muscle tone, elasticity and stiffness were measured from gastrocnemius medialis (GM), tibialis anterior (TA) and vastus medialis (VM) in resting state and in contracted state by MyotonPro. MicroFET 3 was used for manual muscle testing (MMT) of plantar flexion, foot dorsiflexion and knee extension. 6 minute walk test (6MWT) and 10 meter walk tests were (10 MWT) performed in both groups. DMD boys were also assessed by North Star Ambulatory Assessment (NSAA). Results: The mean age of the patients were 8.7±3.2 (5-18) years, median NSAA score was 27 (16-34) and 6MWT was 338 meters (52-546). Compared to healthy boys, there were significant decrements in MMT, walking speed and 6MWT (p<0.001). The biomechanical results showed that resting tone and stiffness of medial gastrocnemius was higher in DMD patients (p=0.024, p= 0.028 respectively), and resting stiffness of VM was also higher (p=0.024). The measurements of muscle tone, stiffness or elasticity did not correlate with functional measures. Conclusion: Our results suggest that myotonometric evaluations can be used easily in DMD and resting muscle tone of gastrocnemius medialis is found to be increased in patients. Clinical meaningfulness of the MyotonPro device should be tested in follow-up studies. Keywords: Duchenne Muscular Dystrophy, Muscular Tonus, Stiffness and Elasticity, Myotonometer, NSAA