Myasthenia gravis / by Charles S. Myers.

  • Charles Samuel Myers
Date:
1902?]
Catalogue details

Licence: In copyright

Credit: Myasthenia gravis / by Charles S. Myers. Source: Wellcome Collection.

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    intensity be alternately applied and discontinued for a small but adequate number of times, each period of tetanisation and of rest lasting a few seconds, the tetanus so produced in the muscle will gradually diminish in force and extent, until finally only at the instant of each reapplication of the current a brief contraction occurs,—similar to that produced by the closure of a constant current,—while during the passage of the current the muscle remains in a state of very feeble contraction, or perhaps exhibits no contraction at all. If the intensity of the current be now increased, or if after a pause of thirty seconds or more the original strength of current be reapplied, a repetition of these phenomena will be obtained, namely, a tetanus at first persisting throughout the application of the stimulus, followed by others of gradually diminishing intensity, and finally ending in exhaustion. Also if the faradic current be applied without intermission during a period varying from twenty-five seconds to a minute, a similar diminu¬ tion in contractile power will be observed, which sooner or later, according to the strength of the stimulus and the stage of the disease, gives place to a condition of complete relaxation. This series of phenomena constitutes Jolly’s myasthenic reaction. It is to be borne in mind that no feature of this disease is so marked as the irregularity of its course. At one moment the patient shows abnormal exhaustibility in one part; in a few days or weeks he may be well, or he may develop the same sign in another part. It is perhaps a result of this irregularity that the myasthenic reaction has not always been discovered in cases which otherwise exemplified the type of the disease. In one case, at least, in that of Wernicke, a sub¬ sequent observer, Toby Cohn (^^), failed to corroborate the previous discovery of abnormally rapid exhaustibility. The muscles of the limbs are the most convenient for the demonstration of the reaction. Possibly in certain fatal cases of myasthenia gravis, where the limbs were not obviously affected, and the myasthenic reaction was unob¬ served, the characteristic electric action would with care have been elicited from the muscles of deglutition or respiration. The myasthenic reaction clearly demonstrates an extraordinary inaptitude for prolonged muscular activity. The same condition is reflected in the volitional muscular actions of such patients. The typical condition of the voluntary muscles in cases of myasthenia gravis is that, at the beginning of the day or after adequate rest, they react normally or fairly well; but towards evening or after use, they become tired out and contract feebly, if at all. We have thus before us three signs which may be described as pathognomonic of myasthenia gravis. They are—(1) ready fatigue of certain or general voluntary movements either to a succession of tetanising currents applied to the nerve or to volitional impulses descending from the brain; (2) the exacerbations and remissions shown in the course of the disease; and (3) the tendency to a fatal
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