Investigation of biomechanical properties of affected muscles in Parkinson's patients with the MyotonPRO device

Parkinson's disease is a progressive neurodegenerative disease characterized by bradykinesia, resting tremor, rigidity, and postural instability, resulting from dopaminergic cell loss in the substantia nigra. The aim of this study was to quantitatively correlate muscle viscoelastic properties with clinically used diagnostic and staging scales for Parkinson's disease and to support subjective assessments with objective numerical data. Furthermore, by holistically examining the disease severity and the primary affected regions, a prognosis map based on quantitative values was developed for each stage. The study included 10 female and 21 male individuals diagnosed with Parkinson's disease and a control group of 12 female and 20 male individuals without any neurological disease. Participants underwent neurological examinations and were assessed using the UPDRS scale. Tone(F), stiffness(S) and elasticity(D) values of 10 muscles that provide primary movement in the head, neck and upper extremities (m. orbicularis oris, m. masseter, m. semispinalis capitis, m. sternocleidomastoideus, m. trapezius, m. deltoideus, m. biceps brachii, m. triceps brachii, m. brachioradialis, m. extensor digitorum) were measured with the MyotonPRO device at four different times. The disease duration in Parkinson's patients was 5.14±4.76 years in males and 7.44±5.50 years in females; UPDRS score was 19.43±11.54 in males and 35.40±30.76 in females. Findings showed significant differences in terms of gender and muscle level. Higher tone and stiffness especially in the proximal muscles in the Parkinson's group; Decreased elasticity and increased stiffness in distal muscles indicate the direction of spread of rigidity. In addition, this study demonstrated with quantitative values that rigidity progressing from axial to distal is a basic biomechanical and viscoelastic indicator reflecting the clinical progression of the disease.