Evaluation of the Torque Developed by the Elbow Flexors in Pa-tients with Neuromuscular Diseases

In planning the optimum treatment for patients with neuromuscular diseases (NMD), it is essential to know as much as possible about their functional state. Assessment of the strength of certain muscles is the most direct measure of motor deficiency. In the development of normative data needed for patients with NMD, the use of torque measurements is required. Forty-nine patients (31 men and 18 women, mean age 33 ± 8,9) were included in the study. Five groups of patients, each having one of five different NMDs, were formed. We tested unilaterally the biceps brachii muscle that normally generates the highest torque. For this purpose an electronic brace enabling isometric measurements of torque during elbow flexion was designed. The patients produced 3 maximum voluntary elbow flexions that lasted about 3 s and separated by a pause of about 3 s. Force development was rapid with continuous build-up and isometric. About 15 s later the patients produced the last maximum voluntary elbow flexion, keeping it as stable as possible for a period of 30 s. Patients with mitochondrial myopathy (MM), having the longest mean time to maximum torque (1191.7 ms), elicited the highest mean torque in both short (1.34 Nm) as well as in 30 s-long maximum elbow flexions. Patients with facioscapulohumeral muscular dystrophy (MD-FSH), having a mean time to maximum torque (537.66 ms) about half as short, elicited the lowest mean torque in both the short (0.29 Nm) as well as in 30 s-long maximum elbow flexions. Patients with Becker muscular dystrophy (MD-B), having a mean time to maximum torque (1090.5 ms) about twice as long as patients with MD-FSH, elicited a higher mean torque in both short (0.82 Nm) and 30 s-long elbow flexions. Finally, patients with limb-girdle muscular dystrophy (MD-RM) and spinal muscular atrophy type 3 (SMA3), having a similar mean time to maximum torque (472.39 ms for patients with MDRM and 505.92 ms for patients with SMA3), also elicited similar torque in both short (0.45 Nm for patients with MD-RM and 0.65 Nm for patients with SMA3) and 30 s-long maximum elbow flexions. The results of the study show that the methodology developed to quantitatively measure the torque developed by elbow flexions in patients with NMD enables the characteristics and natural course of NMD to be more objectively documented. Accordingly, the optimum treatment for patients with NMD could be restored.