The contraction may affect either the extensors or the flexors; in the former case—in writing, for instance—the pen can with difficulty be kept upon the paper, and the stroke movement is interfered with; if the spasm is of the flexors, which is of the most common occurrence, it usually affects the fore finger and thumb; the pen is then forced downward, and upon attempting to make the upward movement catches in the paper; besides, there may be with this a flexion and adduction of the thumb, which causes the pen-holder or pencil to be twisted from the grasp, occasionally with sufficient force to throw it to some distance. The other fingers may be similarly affected. The supinator longus is quite a common seat of spasm, the pen being thereby drawn from the paper by a partial supination of the forearm.
Sometimes the character of the spasm cannot be described, the hand seeming to run away with the pen.
The patient who feels these spasms or contractions coming on soon changes the manner of holding the pen-holder, so as to relieve the affected muscles and to use those which are but slightly or not at all affected. Many grotesque manners of writing may thus be encountered. One sometimes employed by those seriously affected is to grasp the holder in the closed hand, holding it nearly at a right angle to the forearm, all movements being made with the whole arm, thus relieving the finger-muscles. The diagram on p. 457 shows the method of writing adopted by a patient who has a marked spasm of the flexors of the fingers and thumb, preventing his writing in the ordinary manner; he is also the subject of telegraphers' cramp.
These means, however, give but temporary relief, as, sooner or later, if writing is persisted in, the muscles of the arm and shoulder become implicated.
In telegraphers the extensors of the wrist are frequently affected, so that the operator is unable on account of the spasm to depress the key of the instrument with sufficient force to close the circuit, the signals being made, so to speak, in the air, or else a dot (.) is made in place of a dash (—). The extensor spasm seems to be the most frequent form of the cramp among telegraphers, many of them saying that they are unable to keep their fingers upon the key-knob. It will generally be found that the characters that are the most difficult to make are those which are composed entirely of dots, such as h (....), p (.....), 6 (......), or those ending with dots, such as b (—...), d (—..), 8 (—....). Some of the spaced characters are also difficult to make, such as z (... .), & (. ...), y (.. ..).
FIG. 29.
Occasionally one finger will become rigidly extended during telegraphing, and any attempt to prevent this will bring on great discomfort and greater disability. When, more rarely, it is the flexors which are affected, the key is depressed with undue force at the wrong time, and a dash is made where a dot was intended, or an extra dot or so introduced, or the proper spacing of the characters prevented, thus rendering the message unintelligible.
The telegraph operators who experience the most difficulty in transmitting usually have a cramp of the extensors, and those having the most difficulty in receiving (writing) usually have a cramp of the flexors, although the reverse is occasionally seen.