Tetanus is of different kinds. It is divided into the idiopathic, or that which arises entirely from some disorder of the system, and the traumatic, or that which is caused by a wound. It may be acute or chronic; the former arising suddenly, and soon terminating, generally affecting the whole body, and being often fatal; the chronic being less severe and of longer duration, usually partial in its extent, and mostly terminating in recovery. Tetanus may be general or partial, and when partial it is mostly confined to the neck and jaws, constituting trismus, or locked jaw. It is called opisthotonos, when the body is curved backwards so as to rest on the back of the head and the heels, which it most commonly is; emprosthotonos, when it is curved forwards; and pleurosthotonos, when it is drawn to one side,-but this is very rare.

In acute Tetanus the patient usually first complains of stiffness and pain in the neck and jaws, as if from a cold; and his countenance is observed to have a peculiar expression, resembling a painful smile, because the corners of the eyes and mouth are distorted and puckered by spasm of the muscles of the face. The mouth becomes permanently closed, and there is great difficulty in swallowing. To these symptoms succeed a fixed pain at the pit of the stomach, shooting to the back, and a convulsive difficulty of breathing; and the spasm now extends to the other muscles of the trunk and limbs, rendering them completely fixed and rigid. The abdomen feels remarkably hard; there is obstinate constipation, and frequently difficulty in making water; the pupils of the eyes are contracted; and the saliva flows from the mouth, because the patient is unable to swallow it. This spasm never ceases entirely; but it has occasional remissions of violence, alternating with aggravated paroxysms, which are easily induced by the slightest irritation or disturbance. Meanwhile the patient is perfectly sensible, and the pulse may be natural, except during a severe paroxysm, which quickens it, and causes perspiration and thirst.

If the case is about to end fatally, the paroxysms become more frequent and violent, and the breathing more and more embarrassed by spasm of the diaphragm and the muscles of the throat; and at last the patient dies, either from exhaustion or from suffocation. The most usual period of death is the third or fourth day; sometimes it is postponed to the eighth or tenth, but rarely later. On the other hand cases of death have occurred within twenty-four hours. When acute Tetanus terminates favourably, still the patient's recovery is not complete for weeks or even months; partly because of the strainings and lacerations which the muscles have suffered, partly because of the remaining tendency to spasm, which very slowly yields, and is apt to be temporarily aggravated by very slight causes, especially cold and damp. But in some rare instances the disease has been removed almost instantaneously by the removal of its exciting cause.

Tetanus may be caused by wounds and external injuries of every description, but especially by lacerated and punctured wounds of the hands and feet, gun-shot wounds, compound fractures, compound dislocation of the thumb, and wounds irritated by foreign matters, or in which nerves are exposed. Mr. Morgan has even known it caused by a blow with a schoolmaster's ferule. Tetanus has been a consequence of inflammation of the stomach; of strangulated hernia; of the irritation of an emetic on a stomach disordered by habitual drunkenness. Gooch gives a case produced by disease of the breast; and Farr knew it caused by pulmonary abscess. Uterine irritation is by no means an uncommon cause. Whyte gives the case of a girl, aged twenty, who caught cold during the menstrual period, and died of Tetanus within eighteen hours.

Dr. Gregory of Edinburgh used to mention a case of a man who fell asleep in moist grass, and awoke with a stiff neck, which afterwards went on into regular Tetanus. Sir James McGregor tells us that in the Peninsular War the complaint supervened in every description, and in every stage of wounds, from the slightest to the most formidable; the healthy and the sloughing; the incised and the lacerated; the most simple and the most complicated. It has been known to arise from the sticking of a fish-bone in the throat; from a slight wound of the ear by a musket-shot; from the mere stroke of a whiplash under the eye, although the skin was not broken; from cutting a corn; from a bite on a finger by a tame sparrow; from the blow of a stick on the neck and on the hand; from the insertion of a seton, etc. Penetrating wounds upon the sole of the foot, such as are often made by treading upon a nail, or a splinter, and laceration or other violence done to the ball of the thumb, are very apt to be followed by tetanic spasm. Professor Robinson, of Edinburgh, was once at table, when a negro servant lacerated his thumb by the fracture of a china dish. He was seized with convulsions almost instantly, and died with tetanic symptoms in a quarter of an hour.

Tetanus is much more common in hot than in cold countries; and where the complaint arises from wounds, the longer the disease delays its attack after the local injury, the milder in general does it prove, and the better is the prospect of its terminating favourably.

When the disorder arises from exposure to cold or damp, it comes on much earlier; often in a few hours. If, for example, the exposure takes place during the night, the complaint may begin to show itself the next morning.

Poisoning by Strychnine is very liable to be mistaken for Tetanus, as the symptoms are very similar. Sir Thomas Watson mentions a case which occurred at the Middlesex Hospital, where two patients were ordered one twelfth of a grain of Strychnine each every six hours; and the person who dispensed the medicine "through mistake or negligence" gave them each a grain at one dose. Half an hour after the dose was taken one of the patients was seized with tetanic spasms, and came near losing his life; in the other patient the symptoms were milder.