ELECTRICAL REACTIONS
The examination of the electrical reactions of the muscles concerned in a tic is a clinical method seldom, if ever, resorted to, and we can scarcely expect it to yield decisive results from the symptomatological aspect. As with the reflexes, it may happen that we cannot afford to neglect its diagnostic significance in certain cases. For example, we have had occasion to test its worth in studying the case of young J., whose trouble consisted in a clonic tic of elevation of the left shoulder, and a tonic attitude tic of the left arm whereby it was firmly applied against the body. No important alteration in electrical contractility was discovered, although the response in the upper part of the left trapezius—which, by the way, was more voluminous than on the right—was brisker than in its fellow. On the other hand, the right deltoid, sternomastoid, and pectoral, were more excitable than on the left.
Here, of course, the evidence supplied by electrical examination only served to confirm the knowledge gathered from other clinical sources.