Cases apparently beginning in the face are reported, when the distorted expression resulting is very characteristic.
Aran first, and Roberts afterward, divided cases of the disease into two groups, the partial and general. In the former are included those involving the extremities only; in the latter become involved, sooner or later, the muscles of the trunk, neck, face, mouth, pharynx (muscles of deglutition), thorax (muscles of respiration), and even of the abdomen. Even the tongue is reported as undergoing atrophy.
General wasting palsy, as was early observed by Roberts, is unquestionably a rare disease, and in no case have all the muscles of the body been found implicated in one individual, and a few seem altogether exempted. Such are the muscles of mastication and of the eyeball, including the levator palpebræ.
A second muscular symptom, more or less distinctive, is fibrillar contraction. This consists in a wave-like contraction running along small bundles of muscular fasciculi. The contractions occur spontaneously or are excited by any slight stimulus, as a breath of air or a dash of water, or by tapping the patient, or passing a galvanic current through the parts, and at any stage of the disease, except that they do not occur in muscles wholly destroyed. Sometimes they can be felt by the patient. At other times he is wholly ignorant of them. They are not invariably present, and often they have been observed in muscles atrophied from other causes. They possess, however, a certain amount of diagnostic value, especially when spontaneous.
More rare, and less destructive, are cramps, twitches, and clonic contractions of groups of affected muscles. These, when present, are sometimes exceedingly painful.
Coincident with the wasting of muscles is their loss of function. The power of abducting and adducting the fingers gradually disappears, so also that of flexion and extension, and everywhere the loss of function goes pari passu with the atrophy. As Roberts graphically puts it, "The tailor discovers that he cannot hold his needle; the shoemaker wonders he cannot thrust his awl; the mason finds his hammer, formerly a plaything in his hand, now too heavy for his utmost strength; the gentleman feels an awkwardness in handling his pen, in pulling out his pocket handkerchief, or in putting on his hat. One man discovered his ailment in thrusting on a horse's collar; another, a sportsman, in bringing the fowling-piece to his shoulder."
Along with the atrophy of muscle and loss of power comes a gradually diminishing response to electrical stimulus. Direct muscular faradization fails first to excite contraction, and sometimes fails completely even before voluntary mobility is lost. Indirect muscular faradization continues longer to excite contraction, but it also finally fails. Response to the constant current continues still longer, but it also finally fails to elicit contractions, stronger and stronger currents being required, until finally all fail. The galvanic excitability of nerve-trunks is maintained for quite a long time, but finally also disappears. Some irregularities present themselves in this respect.
A singular electrical reaction, first described by Remak, and said by him to be of frequent occurrence in muscular atrophy, was named by him deplegic contraction. He describes it as follows: When the cathode or negative pole is put below the fifth cervical vertebra, contractions can be produced in the atrophied muscles of the arm when the anode or positive pole is placed in an irritable zone, which extends from the first to the fifth cervical vertebra, or, still better, in the carotid fossa or the triangle between the lower jaw and the external ear. The contractions always take place on the side opposite to that at which the anode is placed, while when the electrodes are placed on the median line they occur on both sides, although when the current is very weak they are limited to the muscles most seriously involved. Meyer, Drissen, and Erb confirmed Remak's statement, while Fieber, Benedikt, and Eulenburg failed to do so. Remak interprets these contractions as reflected from the superior cervical ganglion of the sympathetic. He bases this view upon the fact that the patient perceived a sensation behind the ball of the eye when the current was closed. Eulenburg, on the other hand, regards them as genuine reflex contractions, independent of the sympathetic, and caused either by excessive irritability of the central reflex apparatus or by an abnormal excitability of the muscles themselves.
Sensibility is, in many cases, unchanged, the tactile sense being as delicate as ever, and pain, except accompanying the cramps above described, is absent. At times, however, the atrophy is preceded by paroxysms, which may or may not accompany the clonic contractions referred to. It is sometimes in the course of nerve-trunks, but as often diffuse, as though the muscles themselves were its seat. At other times it is variously described as a soreness, an aching, or a rheumatic pain. Accompanying advanced degrees of the atrophy, however, there is very rarely—in 3 out of 105 cases, according to Roberts—a slight diminution of sensibility, especially in the ends of the fingers, while the faradic sensibility may be similarly diminished.
Modified sensations, as those of cold, numbness, and formication, may be experienced, and reflex excitability may be increased, while the knee-jerk is said to be absent. Unusual sensitiveness to cold is sometimes noted, and a loss of muscular power under its influence, which is again restored by artificial warmth.