A duration matching method for the measurement of jitter in single fibre EMG

A new microprocessor method for on-line measurement of jitter in SFEMG is described. The method is based on a duration matching procedure: automatic detection of the repetitive occurrence of two single fibre potentials with stable durations and time-locked to one another. During the investigation of a motor unit a potential pair is accepted or rejected for the determination of jitter on the basis of the potential durations and the interpotential interval; the time criteria are set by the first potential pair measured. The measuring device consists of a microprocessor and an analog interface; it is small and can be connected to any EMG equipment. Compared with the methods previously described the duration matching method (a simple pattern recognition procedure) has the following advantages: the measurement during activation of several motor units is faster and more reliable; the 'technical jitter' is smaller, which allows a more accurate determination of the normal range. Consequently, the method yields values of physiological jitter which are significantly smaller than those previously described.