On the contractility or irritability of the muscles of paralysed limbs, and their excitability by the galvanic current, in comparison with the corresponding muscles of healthy limbs / by Robert Bentley Todd.

  • Todd, Robert Bentley, 1809-1860.
Date:
[1847]
Catalogue details

Licence: Public Domain Mark

Credit: On the contractility or irritability of the muscles of paralysed limbs, and their excitability by the galvanic current, in comparison with the corresponding muscles of healthy limbs / by Robert Bentley Todd. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    tions in that limb will be manifestly less than those in the uninjured limb. We must look then to the state of the nerve to explain the different effect of the electric current upon the muscles. When the nerve is in a state of irritation, or, in other words, when the nervous force in it is in a plus condition, so to speak, the galvanic stimulus will take great effect ; on the other hand, when the nervous force is depressed, or in a minus con- dition, the galvanic current takes little or no effect. Galvanism may, therefore, sometimes serve as a test to distinguish between an irritant and a depressing lesion of the brain. In using this test, however, the practitioner will do well to bear in mind, that an irritant disease of the brain is not necessarily inflammatory, but that, on the contrary, in- flammation of the brain is very frequently most depressing in its effects. A spiculura of bone or a meningeal tumour may be irritant in its effects, but not inflammatory; whilst a patch of red softening, which is distinctly inflammatory, will often produce great depression, both local and genei'al. These views suggest what appears to me to be the true ex- planation of the remarkable tendency of strychnine to affect paralytic linabs first. It wiU scarcely be doubted, now-a-days, that a medicine which exercises such potent influence upon the body, when given in so minute doses as one-eighth or one- fourth of a grain, must do so through the blood. This ma- terial, being taken up into the blood, circulates with that fluid wherever it flows, to all parts of the cerebro-spinal centre, equally on both sides, if the circulation on both sides be in eqvdlibrium. But if there be any lesion on one side of the brain, which from the morbid irritation, or for purposes of repair, attracts a larger quantity of blood to or around it than that which flows to the corresponding part on the opposite side, then a greater amount of the strychnine will be accumu- lated there, and that part will become the seat of irritation fluence is clearly exerted through the nerve, for in applying galvanism to a muscle, it is of no consequence in what direction the current may pass.