Electro-physiology and electro-therapeutics : showing the best methods for the medical uses of electricity / By Alfred C. Garratt.
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Case. M , aged fifty-two, suffered, for six months before the first consultation, from numbness and formication about the left hand, with severe nocturnal pains along the tips of the fingers, and at their metacarpal ends. The patient rarely had pain in the thumb, and none in the palm of the hand. There was frequent vertigo. Now, to determine the character of this numbness, the sesthesioscope was tried, and the patient was found to be able to distinguish one tenth of an inch ecpially well at the tips of the middle and third fingers of both hands ; i. e., of the sick hand as well as the well hand. The instrument therefore aided in the determination of the diagnosis, by show- ing that the sensation of numbness was purely subjective, but doubtless originating in the encephalon, as does tinnitus aurium, yet not the actual result of a true paralytic affection. This instrument is essentially what is known to mechanics as a " beam compass." It consists of a square rod of brass, four inches in length, graduated and marked into inches and tenths of inches. At one end of this is a fixed point one inch long projecting at right angles, while another such point is arranged so as to slide along on the graduated beam, much like a shoe- maker's measure. Certain precautions are necessary here in order to insure trustworthy results. And, first, it is important that the patient should not know what is expected ; therefore he should not know why the instrument is applied; and the points should not be seen by him, so that the eye may not influence his answers to the tactile impressions. It is of all importance, moreover, to make the two points to touch the skin exactly at the same time, or there will thus be produced two successive impressions, which would alter the value of the result. We may use a pair of common dividers, or carpenter's compasses, in the same way and for the same end.