HISTORY.—Some of these neuroses have been recognized for years; this is particularly true of writers' cramp, the earliest notice of which I have been able to discover is in a small work by Ramazini,1 printed in 1746.
1 Bern. Ramazini, Treatise on the Diseases of Tradesmen, etc., translated by Dr. James, London, 1746.
Most of the articles upon this subject have been written during the last fifteen or twenty years.
ETIOLOGY.—Many of our every-day actions, which we perform almost automatically, are the result of months and even years of practice; this is well exemplified in the act of writing. At first each letter is made by a separate and deliberate act of volition, and considerable thought has to be expended upon its formation; but little by little the preponderance of the volitional element decreases, until at last we write with but little consciousness of each separate movement, and the act becomes almost an automatic one, the sentence being conceived and the hand committing it to paper with but little thought of the intermediate muscular acts. In a somewhat analogous manner do we learn to walk, each movement being laborious and requiring much thought for its execution: in addition to this, we must regulate the amount of the movement and keep in abeyance all associated muscular action.
This last is spoken of by Hasse2 as an important factor in the etiology of these affections. When, however, any one of the various muscles whose integrity is necessary for the automatic performance of any act becomes affected, let the lesion be in the muscle itself or anywhere in the nerve-substance between it and its centre, or in that centre itself in such a way as to hinder its free response to the nervous stimulus, then the will has to be especially directed to the act in order to counteract the effect of the disability, and some other muscle or group of muscles must be substituted in the place of the one incapacitated. That which was previously performed easily and without fatigue now becomes difficult and exhausting.
2 Handbuch der speciellen Pathologie u. Therapie, “Krankheiten des Nervensystems,” 1te A., Bd. iv., 1869.
It will be in place here to consider in detail the action of the muscles concerned in performing one or two of the acts most prolific of the affections under consideration.
The first of these that will be examined is the act of writing.
Generally speaking, the methods of writing may be divided into two: 1st, where the fingers do all the stroke movements, the arm remaining quiescent except for the lateral movement; 2d, where the pen is held steadily by the fingers and the letters formed by the movement of the whole arm. In the latter the muscles of the hand and forearm are used almost entirely for pen-prehension and poising, although there is generally a slight finger movement for the long strokes; the forearm is allowed to rest upon the bellies of the flexor muscles as a sort of movable fulcrum, the pectorales, teres major, and latissimus dorsi, together with the biceps and triceps, being mainly employed in forming the letters.