The disease occurs both in children and in adults. There is, however, in its etiology, course, and terminations quite a marked difference, as observed before and after puberty. We shall therefore consider, first, spasm of the glottis in children; second, in adults. {70} Spasm in Children. SYNONYMS.--Laryngismus stridulus, False croup, etc. ETIOLOGY.--Predisposing Causes.--The disease occurs most frequently in children from a few months to two or three years old. It is occasionally met with in those still older and up to puberty. It seems to be more often encountered in patients of a strumous habit than in those of a healthy constitution. Rickety children are especially liable to the affection: the German pathologists especially insist upon this factor. Patients of a nervous temperament predisposed to general spasms are especially predisposed to this affection in the larynx. It is a general law that muscles weakened either by disease or by fatigue or by deficient nutrition are especially irritable. In them mechanical as well as other forms of stimuli produce local contraction with great readiness. These contractions are, it is true, rather the expression of the condition of the muscles than of the nerves. The muscular condition must, however, be regarded as a predisposing cause of the spasm. In the same way, perhaps--namely, by the inherited tendency to lower forms of vitality, weakened muscular power--we may account for the fact that family history of similar conditions, such as false croup in other members or in the parents, should be considered as among the evidences of predisposing tendencies to spasm of the glottis. Sex has in this affection, as well as in most laryngeal diseases of children, a predisposing influence. Mackenzie has collected in all, from different sources, 8248 cases. Of these, 5378 were boys and 2870 girls--a proportion of nearly 2 boys to 1 girl. In adults the reverse holds good, females being much more frequently seized than males. It is certain that season has something to do with the development of the disease, but this influence should be regarded rather as a producing than a predisposing cause. Dentition, worms, weaning, or anything which produces an irritation of the alimentary canal may also, by exciting the reflex irritability of the nervous system, become predisposing causes of laryngismus. The influence of dentition has, however, been probably over-estimated.