opposition to the ciliary stream. Of course when, as the result of extensive disease, pathological communications exist between two sinuses, this argument does not hold. In my cases of frontal sinus suppuration, in all of which the antrum has been punctured for purposes of diagnosis, antrum suppuration was excluded with certainty in more than half. This mode of causation, unless pathological communications exist, is therefore doubtful and at all events rare. It is more likely that when the frontal sinus and antrum are simultaneously involved, the affection of both arose from the same cause; still, the important fact must be borne in mind that it may be impossible to cure antral suppuration until the frontal sinus has been treated. Infection from one sinus to another is more likely to occur if the outlet from a sinus, such as the infundibulum, is blocked up by swelling or polypi, or if the free escape of discharge is prevented by packing the nose after an operation. This danger most frequently arises when the nose is packed for haemorrhage following operations for polypi associated with sinus suppuration. Occasionally perhaps infection may be spread by violent attempts at blowing the nose. When the ethmoidal cells are involved primarily, secondary bone changes often occur and other sinuses may be artificially opened.

Chronic Suppuration is most commonly the sequel of acute in only a few instances is it chronic from the beginning. The causes enumerated above generally give rise to acute catarrh or suppuration, which passes off spontaneously when the original affection subsides, or may do so as the result of simple treatment. It is comparatively rare for acute suppuration to become chronic; the conditions under which this occurs may be grouped as follows:

The outlet of the cavity may be blocked and consequently the pus does not obtain a free exit. This may arise as a result of inflammatory swelling of the mucous membrane surrounding the opening. The mucosa is loosely attached around the various ostia, oedema forms rapidly and is often very great. Further, the mucous membrane is thrown into folds, which often persist for some time after the acute inflammation has subsided, and continue to block the opening. Obstruction may also arise from polypi and other growths near the outlet of the cavity, and in rarer cases from a swollen middle turbinate or a greatly deflected septum. The obstruction need not be absolute: partial or intermittent obstruction with incomplete emptying of the cavity is sufficient to prevent recovery.

The natural openings of the cavities are small and badly placed for drainage. Thus the opening of the antrum is at the highest point of the cavity; the openings of the ethmoidal cells are frequently near the summit and are never at the lowest point: the opening of the sphenoidal sinus is high up in its anterior wall; the frontal sinus alone has a dependent exit and this usually opens into a long, tortuous canal. Thus the drainage of these cavities is very defective and the removal of the secretion almost entirely depends upon the action of the ciliated epithelium; when this is

damaged the secretion necessarily accumulates in the cavity. That the situation of the openings has a considerable influence is shown by the relative frequency of chronic suppuration in the various cavities: thus the antrum is the most often affected, the frontal sinus the least often, and when all the sinuses are involved in an acute process the latter is the first to recover (Zuckerkandl).

The severity of the original infection may so injure the tissues lining the cavity that spontaneous recovery is impossible. Changes in the epithelium may occur leading to the loss of the cilia, or much, or all of the epithelium may be replaced by cubical cells. This may be compared to the changes already described as occurring in purulent rhinitis (see page 133), which may also lead to an incurable affection of the nose. Severe infection or persistent suppuration may provoke secondary changes in the mucous membrane or bones, such as polypi, granulations, caries, or necrosis and thus may result in chronic suppuration. The general debility of the patient may predispose to these changes.

Repeated attacks of Catarrh may permanently injure the mucous membrane, which becomes infiltrated with inflammatory products, and after each attack returns less readily to the normal condition: or may lead to gradual constriction of the opening of the sinus. This is illustrated by the following case. A patient came under my care for antrum suppuration of three months' duration, undoubtedly due to a root abscess of the first molar. Removal of the tooth and daily washing out of the antrum effected a cure and the patient remained well for three months. He then contracted a cold, which was followed by a return of the suppuration in the antrum. This was again opened and irrigated through the alveolar margin and a cure once more followed. This time the patient remained well for eighteen months, when, as the result of another cold, the antrum again became affected and although treated in the same way as before a complete cure was not obtained.

The Cause may continue in Action. For example, the cavity may contain a foreign body; or may be acting as a reservoir of pus coming from another sinus; or a carious tooth may have perforated into the antrum. In a very few cases, such as those in which a large opening into the sinus has formed as the result of tubercle, syphilis, or malignant disease, the sinus suppuration may be looked on as chronic from the beginning. Cases due to ozaena may perhaps be added to this category. Killian is alone in considering a large number of sinus suppurations chronic from the commencement. This is against all analogy, as for example of suppuration in the ear, as well as contrary to general experience in nasal suppuration.

PATHOLOGY.

In acute catarrh the mucous membrane lining the affected cavity becomes congested, swollen and oedematous; it is red, semi-translucent and gelatinous in appearance. The swelling is often very marked, may be diffuse or in patches, and is due to obstruction of the efferent vessels. According to Killian these consist of two systems, the chief of which pass out through the ostium, whilst the smaller ones-vasa perforantia-pass out through the bony walls. If all the vessels are obstructed general swelling occurs, and may be so great as to fill the cavity. If the vasa perforantia remain pervious localised patches of oedema only are found. The mucous membrane is infiltrated with round-celled exudation, and in places the epithelium is destroyed. Haemorrhages into the lining membrane or even into the cavity are common. The secretion in the sinus may be thin and serous, purulent, or muco-purulent, in the latter cases being generally mixed with blood. It may also contain cheesy particles. Occasionally in post-mortem examinations an acute fibrinous inflammation of a sinus has been found, with or without secretion; sometimes, but not always, this has been due to diphtheria. Acute catarrh or suppuration is often limited to a single sinus.

Chronic suppuration on the other hand, except in the case of the antrum, is generally multiple, probably because a more severe infection has been required to produce it and this at the same time has involved other cavities. Killian states that 37 per cent. of his cases were multiple. Grünwald gives the proportion at 34.5 per cent., and these numbers agree with my own experience. As regards the individual sinuses, the antrum is probably the most often affected, the ethmoid, sphenoid and frontal sinuses come next in order of frequency. The older reports give a great predominance of antral affections, probably because they were more easily recognised. Laubi stated that the antrum was affected in 75, the frontal sinus in 7, the ethmoidal in 3, and the sphenoidal sinus in 1, and Alexander's statistics are in substantial agreement. Lapalle found the antrum affected 48 times, the sphenoidal sinus 19 times, the ethmoidal cells 6 times, and the frontal sinus 5 times. Mackie found the ethmoidal cells involved 43 times, the antrum 11, the sphenoidal sinus 9, and the frontal sinus 7 times. There is no doubt that the frontal sinus is the least often affected, and that the ethmoidal cells and the sphenoidal sinus are far more often involved than was formerly recognised.

In chronic suppuration secondary pathological changes often occur and may be discussed under the heads of (1) Changes in the lining mucous membrane with the formation of granulations, polypi, or cysts. (2) Disease of the bony walls, periostitis, caries, and necrosis. (3) Changes in the surrounding tissues and neighbouring organs. (4) Remote and constitutional effects.

Changes in the Lining Mucous Membrane. The mucous membrane lining a chronic suppurating cavity always shows signs of inflammation. It is thickened, corrugated, and its vascularity is increased. There is a large amount of round-celled infiltration and in the older cases marked new formation of fibrous tissue. The walls of the vessels are thickened, and scattered through the mucous membrane there may be small pigmented areas, the remains of old haemorrhages. The epithelial lining usually appears as a thin layer of cells which are evidently proliferating, the cilia are often indistinct or absent and the cells cubical in shape. (Zuckerkandl, Harke, Fränkel.) In places the epithelium may be altogether absent, especially in the lower part of the cavity, and the membrane changed into granulation tissue; extensive or total absence of the epithelium is very uncommon. The granulations may later become covered with epithelium and give the membrane a papillary appearance. Polypi similar in all respects to those occurring in the nose may be found occasionally in all the sinuses. They are especially common when the suppuration is of old standing and, as in the nose, probably depend upon disease in the underlying bone. gross lesions of which are frequently found associated with them. Obvious bone disease was present in all the cases occurring in my own practice: also in two cases related by Scanes Spicer. Heymann found polypi in the antrum fourteen times in 250 postmortem examinations: Luschka five times in 60, and Zuckerkandl six times in 300. These numbers are probably in excess of the truth as has already

been explained (see page 187).

Cysts of varying size are also not very rare. They are most often found in the antrum, and apparently arise from distension of the mucous glands. They contain mucus, muco-pus, or, more rarely, serum. Microscopical sections often show round-celled infiltration round the ducts of the glands, and this, or contraction of newly formed fibrous tissue, may obstruct the duct and cause the acinus of the gland to become distended by retained secretion. The glands throughout the mucous membrane show signs of degeneration and partial desquamation of the epithelium. Changes in the Bone. The mucous membrane lining the accessory cavities is so intimately blended with the periosteum that inflammation of it is invariably associated with periostitis. The periosteum becomes greatly thickened, and active changes in its deeper layers may take place and lead to the deposit of new layers of dense bone. This new bone is frequently deposited in an irregular fashion, and gives rise to roughening of the inner wall of the affected sinus, and even to the formation of large osteophytes (see Fig. 103). In other parts of the bone caries or necrosis may at the same time be actively progressing. Caries of the bony walls even in longcontinued suppuration is rare, and its occurrence has been denied; but in recent years these cavities have been so often opened and their interiors inspected that its existence can no longer be doubted. It is most common,

perhaps, in association with suppuration in the ethmoidal cells, but is also found in the other sinuses. Grünwald states that he has found caries thirty-one times in 55 cases of suppuration in the ethmoidal cells, twentysix times in 51 cases of sphenoidal sinus disease, and six times in 33 antral cases. Necrosis may be found in connection with antrum suppuration, the inner wall, which consists of very thin bone, being most often affected. Bone changes are extremely rare in the frontal sinus, but they may occur even here (see Chap. XXI.). Grünwald found disease of the bone ten times in 22 cases, Hubert four times in 14 cases, while Lothrop, Avellis, and myself have recorded other instances.

The changes occurring in the surrounding tissues and neighbourhood may be briefly summarised as follows: (a) Pus from any cavity, as the result of caries or necrosis of the bony walls, may find its way into other

FIG. 103.-A SPHENOIDAL SINUS SHOWING OSTEOPHYTIC GROWTHS.

spaces and infect them. From the antrum it may burst outwards into the soft tissues causing an abscess of the cheek, upwards into the orbit, backwards into the spheno-palatine fossa, or downwards through the hard palate or alveolar border into the mouth. From the frontal sinus the pus is most likely to find its way externally through the inner part of the roof of the orbit, or, more rarely, the posterior wall may be perforated and lead to meningitis or cerebral abscess. In ethmoidal disease the orbital plate of the ethmoid may be perforated, giving rise to cellulitis and abscess in the inner wall of the orbit. Perforation of the ethmoidal cells or of the sphenoidal sinus may also occur into the cerebral cavity and give rise to meningeal or cerebral infection. (b) Extension of the disease may also take place through the lymphatic channels, and perhaps through the veins, without any definite signs of bone disease. Some cases of cerebral complication may be produced by this method of extension. (c) The pus entering the nose produces a general catarrh of the mucous membrane, with oedematous swelling of the parts with Archiv für Laryngol., 1895, ii. p. 303.