Tetanus (derived from the Gr. teinein, 'to stretch'), or LOCK-JAW, is one of the most formidable diseases of the nervous system, and is characterised by an involuntary, persistent, intense, and painful contraction or cramp (see SPASM) of more or less extensive groups of the voluntary muscles, nearly the whole of the body being sometimes affected. The muscles of the neck, jaws, and throat are almost always the first to give evidence of the presence of the disease. The neck feels stiff, the jaws are opened with difficulty, and often become tightly clenched, and the face has a peculiar fixed smile (risus sardonicus). The disease spreads to the muscles of the trunk and the larger muscles of the limbs; the former is almost always strongly arched backwards (opisthotonos); the hands and feet are usually but slightly affected, if at all. These muscular contractions are very painful; a particularly acute pain is frequently present in the lower part of the chest, probably due to spasm of the diaphragm. Some of the muscles affected, as, for example, those of the abdomen, are so rigid as when struck by the fingers to resemble a board, and a perfect remission of the spasm scarcely ever occurs, except sometimes during sleep. Exacerbations of the spasms, on the other hand, commonly come on every ten minutes or quarter of an hour, usually beginning by an increase of the pain at the sternum, and lasting for two or three minutes: and as the disease advances these paroxysms become more frequent. They may occur spontaneously, or may be induced by the slightest disturbance—a touch, a draught, a noise, or the slightest attempt at movement.
During the exacerbations the face of the patient often presents a positively frightful appearance. The tongue is apt to get bitten during the contractions, which are occasionally so violent as to break the teeth, rupture powerful muscles, and, at least in one case, to fracture the thigh-bone. Death usually results from a mixture of causes, but mainly from want of breath, due to the fixed condition of the respiratory muscles, associated with asthenia (loss of power), and flagging of the heart's action. Fever may be absent during the whole course of the disease, and if present is not generally severe. Sometimes, however, the temperature becomes extremely high (110° or 112° F.) just before death.
The disease occasionally occurs after exposure to cold, still more rarely without any discoverable cause whatever. Such cases are called idiopathic. In the vast majority it follows some injury involving a breach of surface (traumatic tetanus). It more frequently attends upon severe injuries, but it may result from a slight prick or scratch, and the severity of the disease bears no proportion to the extent of the wound. Nor does the seat of the wound seem to have any importance; the popular idea that injuries of the thumb are specially apt to lead to it is not supported by statistics. The period of its commencement varies from a few hours to many days after the injury; death occurs in most fatal cases within a week of the first onset. It is met with at all ages, but is much more common in males than females. Idiopathic cases, and those commencing more than three weeks after an injury, are as a rule less severe. But 'taking all forms together in a fair average number of cases, the proportion seems to be 7½ deaths to 1 recovery' (Holmes's System of Surgery).
Various forms of local irritation may set up a localised trismus or lock-jaw, but its distinction from true tetanus seldom presents much difficulty. Tetanus at its commencement is sometimes mistaken for rheumatism, and has some resemblance to Hydrophobia (q.v.). It may be closely imitated by hysteria, but particularly by poisoning with nux vomica, or its alkaloids strychnia and brucia. In these cases the more sudden development of the symptoms, and the less persistent rigidity between the spasmodic paroxysms, are the most prominent distinguishing features.
With regard to treatment, perfect quiet and the avoidance of all possible causes of irritation and excitement are the first things to be insisted upon. The patient's strength must be maintained by liquid nourishment, given by injection, or even administered under chloroform if necessary. Many drugs have been used; chloral in repeated doses perhaps with most apparent benefit, but the great majority of cases have hitherto defied all treatment.
The cause of the disease has long been suspected to be a micro-organism; among other reasons, because tetanus, as a result of surgical operations, has become much less frequent since the introduction of Antiseptic (q.v.) methods. Nicolaier (in 1884) first described the bacillus now known to be the cause of tetanus; but Kitasato, working in Berlin, was the first to obtain pure cultures, and to give a complete demonstration that tetanus must be added to the infective diseases (1889). Methods have since been discovered whereby animals can be rendered 'immune' or incapable of inoculation with tetanus. Tizzoni and Cattani, experimenting with such animals, found a substance in their blood, called by them the antitoxine of tetanus, which neutralises the virus of tetanus even outside of the body, and when injected into other animals produces immunity against, and even cure of the disease (1891). This substance was used in the treatment of the disease in the human subject. Roux, finding that the failures were due to the anti-toxin never reaching the brain, tried (1898) inoculation of the anti-tetanus serum direct into the brain of the affected person or animal.
Tetany is a rare and little understood disease of the nervous system, occurring both in children and adults, characterised by recurring attacks of tonic spasm of various muscles, particularly those of the fingers and toes. It is associated with defective hygienic conditions, imperfect ventilation, poor diet, and in children with Rickets (q.v.). Complete recovery generally ensues; fatal cases are very rare.
It is not yet definitely settled to which of these two very different diseases tetanus or trismus neonatorum (of newborn children) should be referred. It has been supposed on the one hand to be traumatic tetanus, due to the injury to the umbilical cord at birth, and resembles it in its great fatality, and in the extension of the spasms over the larger muscles (of trunk, &c.); the opposite view, that it is an extremely aggravated form of tetany, is supported by the facts that the muscles of the fingers and toes are specially affected, and that improved ventilation alone has been known to produce a great diminution of the disease in lying-in hospitals.
Tetanus, or lock-jaw, both traumatic and idiopathic, occurs in most of the domesticated animals, but most frequently in horses and sheep. It is now proved to be due to the action of a microbe, the Bacillus Tetani, which gives rise to the formation of a ptomaine termed Tetanine, by the action of which the tetanic symptoms are induced. This bacillus is also found in garden-mould, and most probably tetanus is induced by the entrance of the microbe into a wound or exposed structure. Tetanus has been transmitted from diseased to healthy animals by inoculation. The symptoms usually come on gradually, involve most of the muscular structures, which become hard and rigid; the nose is protruded, the limbs move stiffly, the tail is upraised, the bowels are constipated. The patient must be kept perfectly quiet, and in an airy but fairly warm place, and plentifully supplied with cold water, and with soft, sloppy, but nutritive food, which he will usually greedily suck in through his firmly-closed teeth. A full dose of purgative medicine must at once be given; extract of belladonna repeated twice or thrice daily is occasionally serviceable; any discoverable wound or injury should be fomented or poulticed; bleeding, sedatives, and all causes of irritation must be avoided. In adult animals most cases are fatal; but amongst young animals many recoveries occur.