That in the majority of the cases there is an emotional factor is evident to every one who has seen a considerable number, the knowledge that some one is looking on and will notice the disability being almost sure to aggravate the symptoms. This is frequently noticed among telegraph operators, and is well exemplified in the following answer made by a female operator: “If I am working with a disagreeable or fault-finding operator, who I know will make unpleasant remarks about my sending, and break me (break the circuit) on certain difficult letters, it is almost impossible to make those letters correctly with either hand.” Again she says, “If I come to the difficult letters without thinking about them, I can make them much easier than if I look ahead in the message and see them; for instance, some time after I had ceased using my right hand on account of the cramp, an outside occurrence made me very angry; just then a message was placed on my desk, and with my mind fully occupied with my grievance I sent the message with my right hand very easily and quickly.”
Wasting Diseases.—These favor the production of these affections in those predisposed to them by occupation or otherwise, by the constant drain upon the system. Numbness of the fingers and stiffness are occasional symptoms of renal disease, and would naturally aggravate any difficulty of writing and so-forth that the patient might have. Mitchell27 reports two cases of writers' cramp dependent upon or coincident with albuminuria, which were treated in vain until the condition of the kidneys was discovered: under appropriate treatment for this condition one recovered entirely from the cramp and the other improved greatly.
27 S. Weir Mitchell, M.D., “Nervous Accidents in Albuminuria,” Philada. Med. Times, Aug. 1, 1874, p. 691.
Traumatism, etc.—Injuries, etc. occasionally act as predisposing causes; thus cases are on record where the starting-point seemed to have been an ingrowing thumb-nail, and others where it was the pressure of large sleeve-buttons upon the ulnar nerve; and tight sleeves seem to have been the starting-point of inflammatory troubles ending in writers' cramp. An inflammation of the periosteum of the external condyle (node) and a painful ulcer upon the forearm are reported by Runge28 as giving rise to symptoms closely allied to this affection. Seeligmüller29 mentions a case where the symptoms came on after an insignificant grazing bullet-wound of the knuckle of one of the fingers.
28 “Zür Genese u. Behandlung des Schreibekrampfes,” Berl. klin. Wochensch., x. 21, 1873.
29 Adolph Seeligmüller, “Lehrbuch der Krankheiten der Peripheren Nerven, etc.,” Wreden's Sammlung, Kurzer Med. Lehrb., Band v. p. 29.
SYMPTOMATOLOGY.—Owing to the fact that various causes give rise to these affections, and that the different groups of muscles implicated differ with the varying occupations of those suffering, no one stereotyped set of symptoms can be described as applicable to each case, and no one symptom can be looked upon as diagnostic.
The symptoms most frequently seen may be classified under five heads—viz.: I. Cramp or spasm; II. Paresis or paralysis; III. Tremor; IV. Pain or some modification of normal sensation; V. Vaso-motor and trophic disturbances.
These may, and generally do, exist in various combinations, and they may be accompanied by other symptoms of nervousness; they are not of necessity confined to the hand or arm, but may become more or less general. At first they are usually only seen after long continuance of the occupation which produced them, but later any attempt to perform this act will cause their appearance, although it may not be noticed in any other of the daily avocations.
In some of the rarer cases the neurosis makes its appearance suddenly after a prolonged siege of work. It has been generally stated that writers' cramp, for instance, only manifests itself on attempting to write, but this is due to the fact that there is no other occupation which exactly needs the same co-ordination of the muscles, for others can be substituted in the place of those affected. This is particularly seen in the early history of the cases, but when it has become pronounced in character any analogous movement, such as holding a spoon or fork or paint-brush, will be sufficient to produce it. Difficulty in buttoning the clothes with the fore finger and thumb is frequently noticed.