When it occurs in the limbs, attention is usually directed to the fact by pain accompanying the spasms; the muscles are found to be hard and there are frequent twitchings of the limb.  A characteristic reflex is present in the lower extremity, namely, extension of the foot and leg when the sole is tickled.

Cephalic Tetanus is another localised variety which follows injury in the distribution of the facial nerve.  It is characterised by the occurrence on the same side as the injury, of facial spasm, rapidly followed by more or less complete paralysis of the muscles of expression, with unilateral trismus and difficulty in swallowing.  Other cranial nerves, particularly the oculomotor and the hypoglossal, may also be implicated.  A remarkable feature of this condition is that although the muscles are irresponsive to ordinary physiological stimuli, they are thrown into spasm by the abnormal impulses of tetanus.

Trismus.—­This term is used to denote a form of tetanic spasm limited to the muscles of mastication.  It is really a mild form of chronic tetanus, and the prognosis is favourable.  It must not be confused with the fixation of the jaw sometimes associated with a wisdom-tooth gumboil, with tonsillitis, or with affections of the temporo-mandibular articulation.

Tetanus neonatorum is a form of tetanus occurring in infants of about a week old.  Infection takes place through the umbilicus, and manifests itself clinically by spasms of the muscles of mastication.  It is almost invariably fatal within a few days.

Prophylaxis.—­Experience in the European War has established the fact that the routine injection of anti-tetanic serum to all patients with lacerated and contaminated wounds greatly reduces the frequency of tetanus.  The sooner the serum is given after the injury, the more certain is its effect; within twenty-four hours 1500 units injected subcutaneously is sufficient for the initial dose; if a longer period has elapsed, 2000 to 3000 units should be given intra-muscularly, as this ensures more rapid absorption.  A second injection is given a week after the first.

The wound must be purified in the usual way, and all instruments and appliances used for operations on tetanic patients must be immediately sterilised by prolonged boiling.

Treatment.—­When tetanus has developed the main indications are to prevent the further production of toxins in the wound, and to neutralise those that have been absorbed into the nervous system.  Thorough purification with antiseptics, excision of devitalised tissues, and drainage of the wound are first carried out.  To arrest the absorption of toxins intra-muscular injections of 10,000 units of serum are given daily into the muscles of the affected limb, or directly into the nerve trunks leading from the focus of infection, in the hope of “blocking” the nerves with antitoxin and so preventing the passage of toxins towards the spinal cord.