Etiology. — Tetany arises in certain localities, and is not seen again for long periods. It may become epidemic (Bruns). The condition was described by Trousseau originally, who discovered the important symptom known by his name, viz.: that an attack could be in duced in an affected subject by compress ing the arteries and the nerve-trunks.
Tetany occurs in both adults and chil dren, in about equal frequency (B. Sachs), but most eases are seen in the very young. Holt says it is usually seen in early infancy. Barthez and Sanne found it more often in children and most in infants. Griffith found 66 per cent. under two years of age.
The disorder is much more common among the children of the lower classes, and those whose surroundings are un wholesome. It almost always follows upon depressing conditions, overexertion or recognizable disorders or diseases, especially the transmissible ones; hence its pathology is regarded as a toxaemia, or probably of a complex sort, perhaps a mere neurosis. It is frequently associated with rickets. Barely it has resulted from a known poison, such as lead, alcohol, or ergot. It occurs as a finality to, or associated with, structural diseases of the nerves, and is known to result from ex tirpation of the thyroid gland. That the thyroid gland secretes a something, the absence or excess of which is followed by a perturbation of the normal nervous balance, is a fascinating view, of which Ewald makes a strong point. Weiss pointed out the connection between these toxins and tetany. That intestinal 'para sites secrete a peculiarly disturbing toxin is urged by Albu and others. Maestro advocates the administration of thyroid gland, and exhibits clinical findings front this measure which are convincing; and. in this, S. S. Adams follows him confi dently. Tetany was at one time regarded as an occupation neurosis, but Icussmaul corrected this view. Any exhausting dis ease is a possible cause of tetany in those predisposed to this form of motor dis turbance. The connection of the disease with rickets is still a topic of discussion.
The etiology of tetany in childhood is not clear. It never affects healthy chil dren. Rachit:s is of important predis posing influence. The direct cause of the attack is some gastro-intestinal disturb ance, proved by the frequent association of tetany and acute dyspepsia, and the effect of treatment directed to such con ditions. Hauser (Berl. klin. Woch., No. 35, 'M.
Pathological Anatomy.—No constant nor characteristic lesion has been found present at autopsies in tetany. Serous exudation into the cervical cord and into the ventricles of the brain, sclerotic changes, spinal extradural hxmorrhage, atrophy in the ganglion-cells and nerve fibres, and proliferation of the neuroglia are among the conditions found, as enumerated by Dercum.
The subject has been variously viewed by those who have made researches in this line (Langhans. Weiss, Gowers, Schlesinger, and others), and little other than speculations are offered. The facts are scanty as yet, and it is better to con tent ourselves for the present with the view that tetany is due to the effects of a toxin or toxins upon the entire nerv ous system in one so predisposed.
Romme (Gaz. Hebd. de Med. et de Chir., Jan. 24, '97), reviewing the claims of various authors as to the etiology of tetany, concludes that the views of Kasso witz and his school (that it is a manifes tation of rickets). and those of others who would ascribe the condition to any especial primary disease, are incorrect, as there are no constant post-mortem findings in tetany, and it occurs in con nection with various diseases.
Clinical and pathological studies tell us only that the main symptoms are evi dences of mechanical or reflex hyper excitability of the cord and peripheral nerves due to a diversity of causes.
In an analytical study of GS22 chil dren, with special attention to determin ing the nature of tetany and its relation ship to rickets and laryngeal spasm, Cassel (Dent. med. Woch., Jan. 2S, '07) found GO cases of tetany. The nutrition was good in 14, moderately good in 13, poor in 23, and bad in 10. All pre sented spontaneous intermittent spasm, which could be induced by pressure upon the large nerves and vessels of the af fected parts. In all but 3 the facial phe nomenon was present. Only 2 had laryn geal spasm, and both of these presented craniotabes in addition to other symp toms of rickets. Without exception, the children were nervous and slept badly. Fourteen presented a rise of tempera ture; in 9 the disorder was the result of complicating conditions, and in the remainder it arose without apparent cause. In 21 cases digestive disturbance preceded or accompanied the tetany, in 5 there was chronic dyspepsia, in 43 di gestive disorder, in G obstinate constipa tion, and in 4 habitual vomiting. Rickets was present in 52 of the GO cases; in only 8 there was no trace of rickets. Tetany was seen throughout the entire year, al though the largest number appeared to occur in the spring and late autumn. There was no suggestion of an epidemic occurrence of the disease, nor was there any relation as to frequency between tet any, rickets, laryngeal spasm, and cranio tabes. Cassel concludes that tetany is neither a complication of rickets nor of digestive disturbance, but is dependent upon unfavorable conditions of living, improper nutrition, and bad air.