A treatise on the diseases of the nervous system / by William A. Hammond; with the collaboration of Graeme M. Hammond.

  • Hammond, William A. (William Alexander), 1828-1900.
Date:
[1891], ©1891
Catalogue details

Licence: Public Domain Mark

Credit: A treatise on the diseases of the nervous system / by William A. Hammond; with the collaboration of Graeme M. Hammond. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    normal reactions both to faradism and to galvanism change materially. These changes have been termed the reactions of degeneration by Erb, who first described them. The reactions of the nerves and mus- cles differ, and must therefore be considered separately. When the motor nerves are the seat of a degenerative process the reaction of the nerve to both faradaic and to galvanic currents de- creases proportionately as the degeneration increases, and, if the dis- ease is not arrested, all excitability disappears in about- two weeks' time. This is termed quantitative degeneration. The muscular contractility also undergoes quantitative degenera- tion. The rapidly interrupted faradaic current fails to contract the muscles at all, but a slowly interrupted current will for a few days induce slight contractions. The reaction to the galvanic current also gradually decreases. At the end of about the first week qualitative degenerations can be obtained. It will then be observed that the cathodal closure contraction has either diminished considerably or else has disappeared altogether, while the anodal closure contraction, which was formerly insignificant, now takes precedence over all others. Frequently the cathodal and ano- dal opening contractions cannot be obtained at all, but if they can be it will be observed that the cathodal opening contraction is the stronger. Comparing the normal polar reactions with those obtained where disease of the motor nerve exists, we note the following difference: In health : 1. C.C.C. 2. A.C.C. 3. A.O.C. 4. C.O.C. In disease: 1. A.C.C. 2. C.C.C. 3. C.O.C. 4. A.O.C. Sometimes the polar degenerative reactions are not so well marked. In a few instances it will be observed that the anodal closure contrac- tion equals but does not excel the cathodal closure contraction. In that case the reactions are written as follows : A.C.C. = C.C.C. and C.O.C. = A.O.C. If the degeneration of the nerve advances till it is completely de- stroyed, the polar degenerative reactions gradually fail quantitatively and eventually disappear in the reverse order to that in which they are obtained. That is, the first to be lost will be the anodal opening contraction, then the cathodal opening contraction, then the cathodal closure contraction, and finally the anodal closure contraction. If the destruction of the nerve is not completed and if regenera- tion ensues, the electrical reactions gradually return to their normal condition. If a nerve has been so injured that it can not transmit vo- litional motor impulses, and even electrical excitation fails to induce muscular contractions, and then recovery takes place, it will be found that the muscles respond to the will some time before they will react to any form of electrical irritation. When the anterior horn of gray matter in the spinal cord is dis- eased so that the motor cells are involved, there is paralysis.