We have seen that Acute catarrh forms the first stage in diphtheria; it is the result of the action of the specific poison. Similarly we have acute catarrh in measles and small-pox, there being here a specific eruption similar to that in the skin, along with acute catarrh, which may, in exceptional cases, go on to the formation of a fibrinous exudation as in diphtheria. In typhoid fever we may also have acute catarrh, which, according to Eppinger, is of similar significance to the affection of the intestine, being due to the specific agent. Catarrh occurs also as an independent affection, just as nasal catarrh does, and in this case, although usually slight, it may assume a very severe character. Lastly, a catarrh may be set up by the inhalation of irritating chemical fumes.

There is, as in other inflammations, hyperemia and exudation. The mucous membrane is red as seen during life, but on post-mortem examination the redness has usually disappeared entirely, the vessels being emptied by the shrinking of the tissue. The exudation is originally mucous in character, and is not generally very abundant. After a time, as in the case of nasal catarrh, it usually assumes a more purulent character. The swelling of the mucous membrane is not usually great, and there is not commonly any serious obstruction. On the other hand, in children a slight catarrh may bring on a sudden suffocative attack due to spasm of the muscles of the glottis (see ante). As an unusual complication of acute laryngitis may be mentioned oedema glottidis, the condition next to be described.

Oedema Glottidis

This name is applied to a comparatively sudden oedematous swelling, causing often a serious or even fatal obstruction of the larynx. The oedema is in most cases an inflammatory exudation, but it occurs in Bright's disease as part of a general oedema. It may be part of a simple inflammation of the larynx, or may be connected with diphtheria, or the pustular inflammation of small-pox, or syphilis, or tuberculosis; or the inflammation may be propagated from the pharynx and fauces, or from the inflamed perichondrium. The condition is not an oedema of the mucous membrane itself; that would produce a very moderate swelling; but it is an inflammation and cedema extending to the submucous tissue. In most parts of the larynx there is little or no submucous tissue, the mucous membrane being bound down to the perichondrium. There are some parts, however, where the tissue is looser, chiefly the base of the epiglottis, and, to a less extent, the whole epiglottis, the ventricular bands, and, most of all, the ary-epiglottic folds. The epiglottis is swollen, especially at its base; the ary-epiglottic folds are, usually much tumefied, appearing as rounded tumours projecting backwards from the base of the epiglottis. These rounded swellings form indeed the most prominent appearances. The ligaments passing from the epiglottis to the tongue are also sometimes swollen. Examined from above, the tumefied ary-epiglottic folds conceal the parts beneath, but on laying open the larynx after death it is found that the ventricular bands (false cords) are tumefied, although the true cords are usually very little affected. The oedema may affect the submucous tissue in the trachea for some distance below the glottis. If the swollen parts be cut into, a fluid exudes, which is usually sero-purulent and sometimes almost purulent.