[Illustration:  FIG. 26.—­Bacillus of Tetanus from scraping of a wound of finger, x 1000 diam.  Basic fuchsin stain.]

#Clinical Varieties of Tetanus.#—­Acute or Fulminating Tetanus.—­This variety is characterised by the shortness of the incubation period, the rapidity of its progress, the severity of its symptoms, and its all but universally fatal issue in spite of treatment, death taking place in from one to four days.  The characteristic symptoms may appear within three or four days of the infliction of the wound, but the incubation period may extend to three weeks, and the wound may be quite healed before the disease declares itself—­delayed tetanus.  Usually, however, the wound is inflamed and suppurating, with ragged and sloughy edges.  A slight feverish attack may mark the onset of the tetanic condition, or the patient may feel perfectly well until the spasms begin.  If careful observations be made, it may be found that the muscles in the immediate neighbourhood of the wound are the first to become contracted; but in the majority of instances the patient’s first complaint is of pain and stiffness in the muscles of mastication, notably the masseter, so that he has difficulty in opening the mouth—­hence the popular name “lock-jaw.”  The muscles of expression soon share in the rigidity, and the face assumes a taut, mask-like aspect.  The angles of the mouth may be retracted, producing a grinning expression known as the risus sardonicus.

The next muscles to become stiff and painful are those of the neck, especially the sterno-mastoid and trapezius.  The patient is inclined to attribute the pain and stiffness to exposure to cold or rheumatism.  At an early stage the diaphragm and the muscles of the anterior abdominal wall become contracted; later the muscles of the back and thorax are involved; and lastly those of the limbs.  Although this is the typical order of involvement of the different groups of muscles, it is not always adhered to.

To this permanent tonic contraction of the muscles there are soon added clonic spasms.  These spasms are at first slight and transient, with prolonged intervals between the attacks, but rapidly tend to become more frequent, more severe, and of longer duration, until eventually the patient simply passes out of one seizure into another.

The distribution of the spasms varies in different cases:  in some it is confined to particular groups of muscles, such as those of the neck, back, abdominal walls, or limbs; in others all these groups are simultaneously involved.