Axon Count and Sympathetic Skin Responses in Lumbosacral Radiculopathy

BACKGROUND AND PURPOSE: Electrodiagnostic studies can be used to confirm the diagnosis of lumbosacral radiculopathies, but more sensitive diagnostic methods are often needed to measure the ensuing motor neuronal loss and sympathetic failure. METHODS: Twenty-six patients with lumbar radiculopathy and 30 controls were investigated using nerve conduction studies, motor unit number estimation (MUNE), testing of the sympathetic skin response (SSR), quantitative electromyography (QEMG), and magnetic resonance myelography (MRM). RESULTS: Using QEMG as the gold standard, the sensitivity and specificity of MUNE for the abductor hallucis longus muscle were 71.4% and 70%, respectively. While they were 75% and 68.8%, respectively, when used MRM as gold standard. The sensitivity and specificity of MUNE for the extensor digitorum brevis muscle were 100% and 84.1%, respectively, when the peroneal motor amplitude as the gold standard. The SSR latency was slightly longer in the patients than in the controls. CONCLUSIONS: MUNE is a simple and sensitive test for evaluating autonomic function and for diagnosing lumbosacral radiculopathy in patients. MUNE could be used routinely as a guide for the rehabilitation of patients with radiculopathies. SSR measurements may reveal subtle sympathetic abnormalities in patients with lumbosacral radiculopathy.

Analysis of Interference Pattern of Quantitative Electromyography in Early Adolescence

OBJECTIVE: To establish turns-amplitude, activity-envelope amplitude and activity-number of small segements (NSS) clouds of normal early teens using interference pattern. METHOD: Forty four healthy early adolescence from 11 to 15 years old participated in this study. The interference patterns were analyzed using quantitative electromyography of the biceps brachi and tibialis anterior muscles. The interference patterns were measured at 3 to 5 different force levels ranging from minimum to maximum and turns, mean amplitude, activity, envelope amplitude, NSS were analyzed. By turns/amplitude, activity/envelope amplitude and activity/ NSS ratio, normal clouds of gender related each parameters were obtained. RESULTS: The turns-amplitude, activity-envelope amplitude and activity-NSS ratio of the biceps brachii and tibialis anterior muscles were obtained. Normal clouds of gender related turns-amplitude, activity-envelope amplitude and activity-NSS for each muslces were established. CONCLUSION: By using normal cloud patterns of turns- amplitude, activity-envelope amplitude and activity-NSS, automatic interference pattern analysis may contribute to diagnose neuromuscular disease in early adolescent patients.

Quantitative Electromyographic Analysis of Deltoid and Supraspinatus Muscles during Shoulder Abduction

Measurements of local shoulder muscle function during shoulder abduction are of a great interest in biomechanics research and in ergonomic applications. There have been so many opinions that the supraspinatus muscle acts in synergy with the deltoid muscle as a single unit throughout the shoulder abduction. However the specific actions of deltoid and supraspinatus muscles have been subjects of controversy. Electromyography is an established evaluation method of biomechanical study. It reflects the electrical activity at the muscle membrane level and indirectly the mechanical output of the muscle. The purpose of this study was to evaluate the role of deltoid and supraspinatus muscles during shoulder abduction by the comparison of motor unit action potentials using a quantitative electromyographic analysis method, to provide a good insight into the biomechanics of shoulder abduction. Motor unit action potentials of deltoid muscle were seen earlier than those of supraspinatus muscle at the time of initiation of shoulder abduction. The Root Mean Square (RMS) voltage of deltoid muscle was increased gradually from 0o to 90o of shoulder abduction, and then decreased gradually above 90o to 180o of shoulder abduction. The RMS voltages of deltoid muscle were significantly higher than those of supraspinatus muscle at each degree of shoulder abduction wholly. There was no differences in the RMS voltages of deltoid muscle, during shoulder abduction between the loading of 1 kg and without loading. However, the RMS voltages of supraspinatus muscle were significantly higher in the loading state than without loading. The Mean Rectified Voltages (MRV) were similar to the RMS voltages of deltoid and supraspinatus muscles during shoulder abduction. Based on these results, we concluded that the deltoid muscle was not only an initiator but also a major contributor in shoulder abduction, where as the supraspinatus muscle acts as a secondary muscle for the initiation of shoulder abduction and a supporting muscle when there is a resistance against shoulder abduction.