The electromyographic interference pattern, usually assessed by its appearance on a screen and its sound on a speaker, is known to be a difficult tool to make an accurate and objective assessment of the interference pattern. To overcome this problem, several methods to quantify the interference pattern such as mean ratio, peak ratio and Nandedkar's cloud method have been developed. So, we used all three of these interference pattern analysis methods simultaneously in 46 normal subjects, 12 neuropathies and 8 myopathies, to investigate which of these methods represent the characteristics of the motor unit action potential(MUAP) in neuropathy and myopathy most accurately. The interference pattern were measured at the biceps brachii muscle with concentric needle electrode while the subject contracted the muscle at various degree, and the turn, mean amplitude, complexity, upper centile amplitude and activity were analyzed. The results were as follows; 1) All 12 patients with neuropathy(100%) and 6 out of 8 patients with myopathy(75%) had mean ratio above and below the control group range. 2) 11 out of 12 patients with neuropathy(91.7%) and 7 out of 8 patients with myopathy(87.5%) had peak ratio below and above the control group range. 3) All 12 neuropathy(100%) and all 8 myopathy(100%) patients showed abnormal findings in the cloud method. 4) These three analysis methods were very useful in chidren who could not cooperate in the conventional subjective electromyography. On the basis of this study, mean ratio and peak ratio methods were found to be a relatively sensitive tools in the evaluation of neuropathic or myopathic disease activity and that they could be done with ease. The Nandedkar's cloud method was most sensitive and represented the characteristics of the MUAP of neuropathy and myopathy most accurately and objectively. Further studies are recommended for the evaluation of monitoring the various neuropathic and myopathic disease activity and its progression. |