The tetanus bacillus remains localized in the part of the body to which it has been introduced, and does not invade other parts. In its development, how ever, certain extremely poisonous sub stances are produced, known as the tetanic toxin. This toxin is absorbed into the blood, and thus reaches all parts of the body. It seems to have been shown experimentally that the te tanie toxin possesses a special affinity for the cells of the cerebro-spinal axis, where it is deposited from the blood and becomes fixed. Editorial (Univ. Med. Mag., Feb., '99).
The phenomena of tetanus are readily produceable in lower animals by the ac tion of minute portions of these toxins introduced into the tissues.
The result of observers with regard to the passage of the toxin to the nervous system, directly along the nerves, has been personally confirmed. It was found that a certain dose of the toxin injected into the substance of an exposed nerve, the puncture afterward being closed, could produce tetanus, while no result followed the injection of the same quan tity into the muscles after a portion of the nerve in connection with the part had been removed. Marie (Ann. de l'Inst. Pasteur, July, '97).
There exists a peculiar affinity between the tetanic toxin and certain cellular complexes of the central nervous system, and this affinity is manifested not only in the case of the central nervous system of the living organism, but also in that of the dead spinal medulla and brain; that is to say, isolated from the organ ism. When an injection is used of an emulsion of these organs,—that is, when the cerebral substance circulates with the blood,—the tetanic toxin, finding the nervous substance in circulation, is com bined with it before proceeding to exer cise its action on the cellular elements of the central nervous system, which is thus spared. Wassermann and Takaki (Presse Mod., Jan. 22, '9S).
Pathology.—The disease is character istically and purely toxic in nature, and without typical or constant morbid an atomical changes. There is apt to be a small, slightly-suppurating wound, with some congestion of adjacent parts. The nerves in the vicinity of the wound have been noted as inflamed, red, and swelled, but characteristic lesions in the nerves or nerve-centres are wanting, although in the brain and spinal cord minute haemorrhages, distension of capillaries, perivascular exudation, and pigmentary or other degenerative changes in nerve cells have been described.
Hypostatic congestion of the lungs is a frequent post-mortem finding, and rupture of muscle-fibres as a result of violent contraction has been seen.
Forensic examination of blood and sonic fragments of tissue from a patient who hail died of traumatic tetanus some five weeks before and whose body had been exhumed for confirmation of the di agnosis. Knowing the unstable nature of tetanus toxin, it was deemed impossible to discover its presence in the blood and tissues, but an attempt was made to do so by filtering the blood through a por celain filter and injecting the clear, red fluid thus obtained into white mice. These little animals received quantities varying from to 1 cubic centimetre of the fluid. Some died immediately after the injection. supposedly from the pres ence of putrid substances, to which they were more susceptible than others which lived for four days and then manifested symptoms of tetanus, from which most of them died, but from which one reeovered. It is evidently possible to dem onstrate the presence of tetanus toxin in the blood after the lapse of a number of weeks and after the dead body has putrefied. Symanski (Centralb. f. Bakt., Parasit., u. Infekt., Dec. 31, 1901).
Prognosis. — The prognosis is grave, about SO per cent. of traumatic and 50 per cent. of idiopathic cases proving fatal.
From personal experience and observa tion as to the mortality following the ordinary sedative treatment of trau matic tetanus it is concluded that the disease is almost always fatal, unless decidedly slow and subacute in its onset and course. Gwilym G. Davis (Annals of Surg., Aug., '98) The two main elements in the progno sis of tetanus are the length of incuba tion and the temperature. The shorter the incubation, the more serious the case; if it he only two, three, or four days' long, the case will be almost cer tainly fatal. Any rise of temperature is ominous, and, the higher it is, the less likely is the case to recover. Rapidity of pulse and respiration is also a bad sign. Courmont and Doyon (Practi tioner, June, '99).