When a patient with paresis or paralysis as the most prominent symptom attempts to write, an intense feeling of fatigue usually appears, and the writing becomes difficult or impossible—not from a too ready response and spasm, but from an inability of the muscles to obey the will; the pen-holder is held in a feeble manner, and sometimes falls from the grasp. There may be a sense of utter weakness and powerlessness, the arm feeling as if glued to the table.
Duchenne39 calls attention to this form of trouble, which he styles paralysie functionelle, and states that it is much less common than functional spasm.
39 Loc. cit.
New methods of holding the pen are as constant in this form as in the spastic, as it is as necessary in one as in the other to avoid as much as possible the use of the affected muscles. A carpet-weaver, seen by myself, was obliged to tie the knots in the warp on the distal extremity of the second phalanx of the thumb, as the extensor secundi internodii pollicis was partially paralyzed, so that he was unable to keep the distal phalanx extended. This condition came on when he was a compositor, and compelled him to change his trade. A condition of spasm had preceded the paralysis.
The first dorsal interosseus muscle is frequently the seat of paresis; this is readily discovered by measuring the power which the patient has of lateral movement of the index finger and comparing it with that of the sound hand.
III. Tremor (Tremulous Form).—Trembling or unsteadiness of the fingers is occasionally seen, usually most marked in the fore finger when the hand is at rest with the fingers slightly separated. In some cases this may be sufficient to cause unsteadiness in work, prolonged work and over-fatigue being most apt to produce it; as previously mentioned, this is one of the premonitory symptoms of professional muscular atrophy. An oscillatory trembling, due to implication of the supinators and pronator, is described by Cazenave,40 which interfered greatly with the act of writing. Tremor is of itself rarely complained of by those affected with copodyscinesia, unless it becomes sufficiently marked to cause interference with work.
40 “Observations de Tremblements oscillatoires de la Main Droite,” Gaz. méd. de Paris, 1872, pp. 212-215.
A peculiar form of nystagmus occasionally seen in miners may be considered as belonging to this category. According to Nieden of Bochum41 it is caused by eye-strain in the defective illumination of the mines, and consists not of a spasm, but of a defective innervation, like the tremor of old persons. C. B. Taylor42 of Nottingham and Simeon Snell43 also speak of this as a fatigue disease.
41 “The Pathogenesis and Etiology of Nystagmus of Miners,” Am. Journ. Med. Sci., Oct., 1881.
42 Quoted by Poore, loc. cit.