[34] This is exactly similar to an encysted tumor which has been opened, and requires the same treatment. The internal surface becomes thick and somewhat hard, like that of a cyst. It differs from an encysted tumor only in its cause and origin.
[35] If pressure be employed early, to a considerable degree, the irritation of the means employed produces pain, and a morbid increase of action, unless we keep down the action by cold, as will be explained when considering the treatment of ulcers.
The second case, has generally been considered as a species of ulcer, and has been named the sinus ulcer; but, although the orifice may sometimes possess the diseased ulcerative action, yet the sinus itself still continues in the suppurative state, and, therefore, cannot heal. These sinuses depend, in different instances, upon very different causes, and, therefore, require a variation in the treatment. The most simple species of sinus may be called mechanical, and is produced by matter flowing from a neighbouring cavity, and which cannot be freely discharged: Thus, for instance, if a deep abscess open at the highest part, or at a point above the level of its bottom, the matter constantly oozes out, and keeps the canal open. This is most apt to occur, when abscesses are formed deep amongst muscular parts; in which case, although the matter point at the centre, yet an accumulation must take place below, and the matter must continue to be discharged by the aperture, when it becomes so abundant as to be raised to the level of the opening; or, being once raised, it continues to flow out. The cure of this may at first be attempted mechanically, by tight bandages, which press out the matter, and keep the sides in contact; but, if the disease have been of long duration, then, whatever may have been its nature at first, we find, that the suppurative action extends along the mechanical sinus, which then becomes affected with a chronic action; in which case, it becomes similar to the second species of sinus. We must, in this species, make an opening at the most dependent part, and employ the means which will be now mentioned in considering the second species, or that produced in consequence of the suppurative action becoming chronic or habitual, independent of any mechanical cause. This may take place, although the aperture have been originally in a proper place, and the matter, instead of being retained and keeping up the disease, shall have been regularly discharged. The case in which this is most likely to happen, is that in which the abscess has been very tedious in its progress, and the action has been, from the first, slow. The distinction betwixt this species, and those which remain to be mentioned, is founded upon the absence of the symptoms which they possess, and by our examination with the probe, which points out the cause and extent, and informs us whether we be near a bone. The orifice is flabby, and has the appearance of the indolent ulcer. The cure of these sinuses is to be attempted, by pressing out the matter by means of proper bandages, or by making a dependent opening, which is generally necessary, at the same time that we raise the action of the part to a proper degree, and render the suppurative action acute and vigorous; in which case, it naturally terminates in the ulcerative, and thus the part has its structure restored. This is most easily effected, by passing a seton, and applying a proper degree of pressure, diminishing the size of the seton gradually, and in proportion to the vigour of the action and the approximation toward health. When, from the situation of the sinus, we cannot pass a seton (which rarely happens in this species of sinus), injections of wine may be used frequently, and pressure applied during the intervals. When these means fail, which is seldom the case, the part should, if its structure permit, be laid open. If this sinus have remained long open, its surface, like that of the chronic abscess, becomes changed, and a coat is formed, like the cyst of a tumour. When this is thick and hard, the sinus has been called a fistula, and it has been deemed necessary to dissect out the tube; but it is in general sufficient to use the remedies which increase the vigour of the action, and make it run its natural progress; such as the seton, or a free incision, if the parts be superficial, or no considerable vessel or nerve runs the risk of being wounded.