Whether sex, per se, has much influence as a predisposing cause is difficult to say, as statistics are wanting, but it is probable that with the same amount of work given to each sex a large proportion would be found among women.
Women are being employed to a considerable extent in telegraphy, and although I have been able to collect but 4 cases of this form of copodyscinesia affecting women out of a total of 43, I have reason to believe it is quite common among them, my mode of collecting statistics (soliciting replies to printed questions) being much more likely to give a larger percentage of answers from men.
Hereditary Influence and Nervous Temperament.—Both of these factors seem to play an important rôle as predisposing causes to these affections. Cases are on record where several members of the same family were the subjects of writers' cramp. The statement made by Erb (vide supra), that neuropathic persons and those who belong to nervous families are more subject to these affections than others, seems to me to be true, at least to a great extent, for a careful inquiry into the history of cases coming under my knowledge has quite often elicited the statement that migraine, functional spasm, epilepsy, hay fever, neuralgia, writers' cramp, telegraphers' cramp, or general neurasthenia has existed either in the immediate family or in the patients themselves. Hasse23 is also of the same opinion.
23 Loc. cit.
Whittaker24 states that many of the cases coming under his notice, if not the majority, occurred in individuals of irritable nervous temperament, subject themselves to, or the descendants of parents afflicted with, migraine, chorea, epilepsy, paralysis, or some form or other of neurosis, but that a certain contingent of the minority of cases occurred independently of any neurosis or any abuse of alcohol or sexual excess.
24 Cincinnati Lancet and Clinic, N. S., vol. iv. p. 496, 1880.
Fritz,25 after studying 25 cases of writers' cramp, found 7 who either stuttered, squinted, or had choreoid movements or œsophageal spasm at the same time; but it is probable that a few of these cases at least were due to some central lesion (post-paralytic chorea?).
25 “Ueber Reflexionsfingerkrampf,” Oesterr. Jahrb., März u. April, 1844, quoted by Hasse, loc. cit.
Beard26 holds an opinion directly the reverse of the vast majority of the authorities upon this subject, and states that this disease occurs mostly in those who are of strong—frequently of very strong—constitution, and that it is quite rare in the nervous and delicate; and when it does occur in those who are nervous it is easier relieved and cured than when it occurs in the strong.
26 G. M. Beard, M.D., loc. cit.