Muscle spike artifact minimization in EEGs by time-domain filtering.

An electronic circuit is described for minimizing or eliminating muscle artifact in EEGs. The principle of operation of the circuit is that of a relatively high frequency (250 Hz) sample-and-hold procedure which is interrupted for the duration of a muscle potential. Detection of the presence of the latter is based on a steepness criterion, with a manually adjusted threshold. The circuit is primarily effective for repetitive single muscle spikes. It is not effective if there is a continuous muscle interference pattern, but it can still be useful if the muscle interference pattern is not truly continuous. Very sharp EEG spikes may also be eliminated or at least altered, but less sharp EEG spikes can be passed with little or no change in their wave form.