GUIDED INTRAMUSCULAR FINE WIRE ELECTRODE PLACEMENT - A NEW TECHNIQUE

This report describes a new technique for placing intramuscular fine w ire electrodes into muscles for kinesiologic electromyographic (EMG) s tudies. Currently, a pair of fine wire electrodes (one active, one ref erence) within a hypodermic needle is inserted into the selected muscl e. The needle is then withdrawn, leaving the two fine wires positioned within the muscle. Electrical stimulation of the muscle through these fine wire electrodes confirms their correct placement. However, if po sitioning is incorrect, additional pairs of wires are inserted within needles until correct placement is achieved, Our ''guided'' method com bines this ''blind'' technique with diagnostic needle EMC techniques. Using a conventional EMG machine and selective activation of the desir ed muscle, the electromyographer inserts the hypodermic needle while m onitoring the muscle's electrical signal through the advancing fine wi re electrodes. This signal is used to ''guide'' the needle into the pr oper muscle. Once correct positioning of the wires is confirmed by the EMG signal, the needle is removed. With this technique, additional ne edle insertions are avoided, electrical stimulation is seldom needed, and rarely studied muscles are accessed as easily as commonly studied ones. We have used this technique with pediatric and adult patients as well as in kinesiologic EMG research and have found it to be well tol erated and reliable.