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part to the loss of the constricting influence of the upper lip. breathers the upper lip appears to be shortened and retracted, whereas normally it covers the teeth, and by its elasticity keeps them in position. If an elastic band be fixed over the teeth, as is often done by dentists, the deformity can readily be overcome.

Three other possible contributory causes may be mentioned. It is obvious that when the upper and lower teeth are in contact, there is a constant pressure on the extremities of the palatal arch, which tends to flatten it out. When the mouth is open this pressure is removed, and one factor in the normal development of the arch is absent. Secondly, when the mouth is closed, the tongue is in contact with the hard palate,

[graphic]

FIG. 50.-UPPER JAW OF PATIENT SHOWN IN FIG 49. SHOWING UNILATERAL
DEFORMITY OF ALVEOLUS. (See Text.) (From a cast kindly made by J. G. Turner.)

except for a small space near its centre (Fig. 51). At this spot a partial vacuum is formed, which helps to retain the closure of the mouth without muscular action, and at the same time tends to depress the centre of the palate. Lastly, the contact of the tongue with the alveolus all round the upper jaw produces a lateral outward pressure, which tends to widen the arch.

The factors producing the deformity in the lower jaw are probably two in number: the lateral compression produced by the tension of the cheeks, as above explained, and the lateral pull of the mylohyoid muscle. This muscle is probably always in a state of active contraction to maintain the open mouth, and the position it assumes in mouth breathers, as shown by section of a frozen skull, makes the floor of the mouth V-shaped. The lateral pressure of the tongue, which remains in contact with the lower jaw, may serve to expand the alveolar arch, and thus to prevent such great deformity as occurs in the upper jaw.

These deformities of the jaws and teeth were apparently first noted by Robert in 1843. They were accurately described by Tomes,2 who considered them due to mouth breathing, as the result of enlarged tonsils. Michel, in 1876, first ascribed them to adenoids. Other observers, Morell Mackenzie, MacDonald, Siebenmann and his followers, considered the 1 Bulletin général de Thérapeutique, 1843. 2A System of Dental Surgery, 1873, p. 140.

deformities due to some inherited tendency. Recent writings on the subject show that a great diversity of opinion still exists. Bloch considers that the high palate is a constant symptom of adenoids, and that it is due partly to the lateral compression of the cheeks, and partly to the impact of the air on the hard palate in mouth breathing. Korner agrees with this, and adds as an additional cause, that the nose having no function to perform, fails to develop properly. Bentzen, as the result of numerous measurements, found that the palate in adenoids was much higher than normal,

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FIG. 51.-SECTION THROUGH A FROZEN SKULL TO SHOW SPACE BETWEEN ROOF OF TONGUE AND HARD PALATE WHEN THE MOUTH IS CLOSED. 1, Antrum; 2, inferior turbinate; 3, space between tongue and palate, probably a partial vacuum; 4, nasal septum; 5, tongue. (After Cryer.)

and that the longer oral respiration persisted, the higher the palate became. The presence or absence of rickets apparently made no difference. Alkan's elaborate measurements and investigations on the development of the skull led him to the same conclusion. On the other hand, Buser measured 514 skulls and concluded as Siebenmann, Swain, and others had done that the high-arched palate and its associated deformities depended entirely upon leptoprosopia, and that it was hereditary. He considered that the palate in adenoid cases was not higher than normal, and explained the constant association of palatal deformity with mouth breathing, by stating that adenoids and other obstructions naturally more often gave rise to mouth breathing in subjects with leptoprosopic heads than in others. Grossheintz considers the deformities mainly due to racial peculiarities. Mayo Collier, who has no hesitation in ascribing the deformities of the jaw to the results of mouth breathing, considers that the air in passing through the mouth sucks air out of the nose, and thus produces a negative pressure in the nasal fossa, which causes a sinking-in of the surrounding parts. This theory overlooks the

fact that the seat of obstruction is usually situated behind the nasal chamber, and further, that the nasal fossae are open in front, so that air can easily enter and equalise a negative pressure. It entirely fails to explain the cases of posterior choanal atresia, in nearly all of which there is a very high narrow palate, although the anterior nares may be normal (Haag). Arbuthnot Lane states that the deformities of the bones of the face are due to the absence of the lateral pressure exerted by the air in passing through the nose and naso-pharynx. Both these theories entirely disregard the existence of corresponding deformity in the lower jaw. Macdonald and Parker consider the deformity of the upper jaw the result of some inherited tendency, and add that by contributing to the narrowness of the nasal fossae, it produces negative pressure behind the nose, and so encourages hypertrophy of the adenoid tissue in the post-nasal space.

Thus most observers agree that the deformities in question are frequently, if not invariably, associated with mouth breathing. Ziem's experiments .demonstrate conclusively that they may result from it. He obstructed the nostrils of puppies and other young animals, and found that great deformity of the bones of the face resulted in later life. There seems every reason to believe that the nasal obstruction precedes and causes the facial deformity. The latter is never congenital, but it follows after years of mouth breathing; the changes can be arrested, and will even retrogress, if the cause be removed. That the palatal deformities are more common in leptoprosopic patients, is easily explicable. Adenoids and all other forms of nasal obstruction are more commonly met with in people with leptoprosopic, than in those with chamaeprosopic heads. Moreover, adenoids, when present in the former, are more likely to produce nasal obstruction than when occurring in the latter, and it is the open mouth, and not the mere presence of adenoids which counts. Thus the evidence shows that these deformities really depend upon mouth breathing, and that the increased tension of the soft tissues of the cheeks is the most important factor in their causation.

(4) Symptoms due to Deficient Oxygenation of the Blood. In children with nasal obstruction there is a marked diminution in the volume of air entering the chest during sleep, and in consequence, the blood is insufficiently oxygenated. The small amount of air passing in and out of the lungs is easily demonstrated by watching the child's breathing. If a case of marked nasal obstruction be carefully observed it will be noticed that during sound sleep, air enters the chest only once out of every four, five or more respiratory movements. I have recently observed a child in which the inspiratory efforts during sleep produced retraction of the chest walls without any snoring and without any air whatever entering the chest. After 11 or 12 such attempts to breathe the child partially aroused himself, gasped, drew one long breath, and subsided into sleep again. During sleep this child was always deeply cyanosed and bathed in profuse perspiration.

Disturbed Rest and Sleep. The results of this deficient oxygenation

of the blood are very marked. Sleep is not restorative, and the patient wakes up in the morning tired, fretful, complaining of headache, and looks ill and dark round the eyes. Often sleep is disturbed by terrifying dreams,

and the child suddenly wakes up shouting and screaming. Many children have exactly the same dream every night, and are so frightened that they are often afraid to go to sleep. These "night terrors" are probably in many cases the direct result of partial suffocation.

In severe cases the difficulty in breathing may lead to cyanosis and profuse sweating. These symptoms may give rise to considerable alarm, and it is probable that tracheotomy has more than once been performed for their relief. The seat and cause of the obstructed respiration may, however, be readily recognised by waking the patient, when it will be found that the difficulty in breathing and the cyanosis will at once disappear.

Nervous Symptoms. Nasal obstruction produces, both in adults and in children, a peculiar group of nervous symptoms, to which the term aprosexia was applied by Guye. They consist of inability to fix the attention or to undertake anything requiring close mental application. Even simple arithmetical calculations may become impossible. There is often a considerable degree of stupidity, the memory may be impaired, and it becomes difficult to transact business. The disposition may be altered; adults become nervous, irritable, or morose; children fretful, languid, and unwilling to work or play. In children these symptoms are largely due to the deficient oxygenation of the blood, the restless sleep, and the impaired general health. The night terrors are also an important factor, and may render children highly nervous. Guye ascribed the train of symptoms to interference with the lymphatic outflow from the brain as the result of the circulatory changes in the nasal cavity. It must be remembered that there is a direct connection between the lymphatics of the brain and its membranes and those of the ethmoidal region, and it is a frequent clinical observation-which goes far to confirm this viewthat the symptoms in adults are more pronounced when the cause of the nasal obstruction is seated in the ethmoidal region. The patient's stupidity is emphasised by the silly expression resulting from the open mouth, etc., and the air of abstraction due to the deafness.

Effects upon the General Health. From what has already been said, it will not be difficult to understand that nasal obstruction produces the most baneful effects upon the general health. The disturbed rest, the imperfect oxygenation of the blood during sleep, the frequent catarrhs of the upper air passages associated with mild febrile attacks due to septic absorption, the ill-development of the jaws and teeth, the deformities of the chest walls, together with the other consequences of the loss of the functions of the nose and the harmful effects of mouth breathing, will readily explain this. Children become anaemic, stunted, and ill-developed, and are always ailing. The increase of bodily and mental activity and

the rapidity of growth following a successful operation are frequently surprising.

(5) Deformity of the Chest Walls due to Obstructed Respiration during Sleep. Children with adenoids or other form of nasal obstruction will often be found to have some deformity of the chest. There may be flattening of the sides of the chest, with projection forwards of the sternum. -the typical pigeon-breast (Fig. 52). This may be associated with a depression in the epigastric region. In the other variety there is a shallow depression running round the lower ribs,-Harrison's sulcus, which is often

[graphic]

FIG. 52.-DEFORMITY OF CHEST AND FACIAL EXPRESSION RESULTING FROM
PROLONGED NASAL OBSTRUCTION. (From a photograph.)

associated with a deep depression over the lower half of the sternum (Fig. 53). One or other of these deformities is very common in young children with marked nasal obstruction, and the explanation is simple. Although the child sleeps with its mouth open, careful observation will show that respiration is carried on almost entirely through the obstructed nose (Macdonald and Parker). This fact may be easily tested by holding a fine film of cotton wool in front of the nostrils and mouth of the sleeping child. Macdonald ascribed this to an "overpowering instinct" for nasal respiration which asserted itself in the young during sleep. MacKeown pointed out the fallacy of this, and suggested a purely mechanical explanation, viz. that during sleep the tongue falls back in contact with the palate and obstructs the passage through the mouth. If the chest walls

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