The methods of classical electric diagnostics used before an advent of electromyography and radiodiagnostics methods, was aimed at identification of changes of nerve conductivity threshold – both quantitative changes or (partial, full) reaction of muscles regeneration. Determination of muscles denervation is based on determination of axon excitability, i.e. the minimal degree of muscle activation at impulse current supply. The control of minimal muscle activation was carried out visually, the current was supplied to the motor point of the muscle. The minimum current intensity at maximum duration (300 msec). Now an estimation of "current intensity -duration" is carried out less often for some reasons [1,2,9]:
1. The method is based on subjective criterion of muscle activation (visual);
2. Significant labor input of the research;
3. Ambiguous interpretation of the results, because at partial preservation of not affected nervous fibers in the nerve the "current intense-duration" curve will be a sum of excitability of affected and not-affected fibers;
4. Sufficient persistence of changes of the curve at an estimation of reinnervation in comparison with needle EMG;
5. There are no modern devices for carrying out of the examination. Previously used device UEI-1 is thoroughly off-market and obsolescent, the process of its manufacturing was stopped more than 15 years ago;
6. Classical electric diagnostics helps to estimate an excitability of only low-threshold, low-myelinated fibers. In view of the fact, that axons of the highly myelinated fibers are affected at loss of connection with neuron body earlier than axons of non-myelinated (low-threshold) fibers , we can say, that the method of estimation of M-response parameters is more sensitive, than classical electric diagnostics.
Electroneuromyography (ENMG) is a method of registration and examination of bioelectric activity of a muscle at rest and at self-produced tension. In the broad sense of the word, the term electromyography includes all kinds of myography techniques (global ENMG, needle ENMG and stimulation techniques).
ENMG together with clinical data helps to solve many diagnostic problems: