TETANUS (from Gr. _____, I stretch), a disorder of the nervous system, consisting in an increased reflex excita-bility of the spinal cord and manifesting itself by painful tonic spasm of the voluntary muscles throughout the body. The disease shows itself under various conditions. It occasionally occurs, particularly in tropical countries, with-out apparent cause, and has thus been known to affect numbers of persons simultaneously (idiopathic tetanus).
It is sometimes observed in new-born children (trismus neonatorum) and in parturient women (puerperal tetanus). But by far the greater number of cases occur in connexion with a wound or other injury, more especially in the ex-tremities, probably implicating some of the peripheral nerves. Certain forms of injury, as punctured, lacerated, and gunshot wounds, are more liable to be followed by tetanus than others. In many cases the liability bears no proportion to the extent of the wound. Exposure to cold after injury is an important exciting cause. The symptoms of tetanus in its most usual forms generally appear during the healing process of a wound, but occasionally they arise after cicatrization is completed. Sometimes they are pre-ceded by appearances of irritation in the wound or its neighbourhood, but this is exceptional. The earliest indi-cations of the disease usually show themselves, no matter where the wound is situated, by stiffness about the muscles of the jaw, causing difficulty in opening the mouth, which soon increases to lockjaw or trismus. This is accompanied by spasm in neighbouring muscles, and the drawn features and exposed teeth give to the countenance the peculiar expression known as risus sardonicus. The rigidity ex-tends to the muscles of the neck, back, chest, abdomen, and extremities, and the body frequently assumes a bent attitude, either backward (opisthotonos), forward (empros-thotonos), or laterally (joleurosthotonos). This general muscular rigidity, which at first is not constant but occa-sionally undergoes relaxation, is accompanied by frequently recurring convulsive seizures, which are readily excited by the slightest irritation, such as from a draught of cool air, a bright light, the closing of a door, &c. In such attacks there is great suffering and the expression of the face is indicative of agony; and the function of respiration may be seriously involved and asphyxia threaten or actually take place. The temperature of the body sometimes rises to a high degree. The attack is usually acute and after a few days either passes off or, as is more frequent, ter-minates fatally, either by asphyxia from tonic spasm of the respiratory muscles or from exhaustion consequent on the violence of the symptoms together with the absence of sleep. Throughout the whole course of the disease the mind is clear. In idiopathic tetanus the symptoms are less severe, the course more chronic, and recoveries more common than in those which depend upon a wound or injury. The puerperal form, with symptoms which differ in no way from those described, is rare and occurs either after parturition or after abortion. Tetanus in new-born children, also a rare form, usually shows itself a day or two after birth by obvious difficulty in the acts of sucking and swallowing ; by the supervention of trismus, together with tonic contraction of the muscles of the limbs and body, sometimes accompanied by convulsive seizures; and by a peculiar low whining cry, seldom absent and very charac-teristic. Various opinions have been held as to the cause of this form of tetanus, some referring it to the wound produced by severance of the umbilical cord, others to pressure upon the bones of the head in parturition, &c. It has not yet been satisfactorily explained. Although sometimes recovered from, it is usually fatal.
The symptoms of poisoning by strychnine bear a strong resemblance to those of tetanus. They are, however, more acute and develop in connexion with something which has been taken; further, the absence of a wound and the fact that the spasm affects the muscles of the extremities first, and not those of the jaws, as in tetanus, serve to establish _ the diagnosis. In HYDROPHOBIA (q.v.), which in certain of its symptoms resembles tetanus, the absence of trismus, the dread of water, and the violent spasms on attempting to drink, together with the history of the case, readily enable a distinction to be made. Various other forms of nervous disease accompanied by tetanic symptoms, such as cerebro-spinal meningitis, hysteria in some forms, &c, may be still more clearly distinguished from true tetanus.
The pathology of tetanus is referred to in the article PATHOLOGY (vol. xviii. p. 391). No constant changes are observed in the body after death from tetanus. The most common are great dilatation of the blood-vessels of the spinal cord and sometimes evidence of inflammatory action, but these are probably the effects of the symptoms rather than their cause.
For the treatment of tetanus many remedies have been employed. Where a source of irritation in or about a wound can be made out, it ought to be dealt with by the surgeon. Of medicinal agents those which diminish the reflex excitability of the spinal cord and relax the spasm are to be recommended. But it is not safe to employ all substances which produce these effects. Thus tobacco and its active principle nicotine act powerfully in this way, but they are attended with danger from their poisonous proper-ties, and the same may be said of curari, conium, calabar bean, (fee., all of which have been used in tetanus. Opium carefully administered sometimes produces a markedly beneficial effect, as does also Indian hemp. Chloroform or ether inhalation greatly mitigates the severity of the spasm. Chloral hydrate and bromide of potassium or ammonium are among the most useful agents which can be employed, and they may be given separately or, still better, in combination. As adjuvants, the warm bath, the absence of all noise and excitement, and the maintenance of the strength by appropriate nutriment should not be neglected.