CROUP. 15 



CHAPTER II. 



CEOUP. ANGINA MEMBRANACEA. LARYNGITIS CKUPOSA. MEM- 

 BRANOUS CROUP. 



ETIOLOGY. Croupous inflammations are inflammatory disorders in 

 which a fibrinous exudation which rapidly coagulates is thrown out 

 upon the free surface of a mucous membrane, but which involves the 

 epithelium only. If the croup-membrane thus formed be detached, the 

 epithelium is quickly reproduced. No loss of substance occurs in the 

 mucous membrane itself, and no scar remains. The diphtheritic process 

 is also characterized by the production of a fibrinous rapidly-coagulable 

 exudation, but differs from croup, the exudation forming, not merely 

 upon the surface of the mucous membrane, but also within its sub- 

 stance. The pressure upon the blood-vessels exerted by this interstitial 

 exudation, as well as by the swollen elements of the tissue, results in 

 sloughing of a portion of the inflamed mucous membrane, and in the 

 formation of a so-called diphtheritic eschar, which, upon separating, oc- 

 casions a loss of substance and consequent cicatrix. Of these two 

 forms of inflammation (the essential duality of which has of late been 

 much in dispute), it is almost exclusively the croupous form which ap- 

 pears in the mucous membranes of the respiratory passages ; and it is 

 only in rare and solitary instances of secondary croup, when that malady 

 forms part of some general acute infectious disorder, as measles, small- 

 pox, typhus, scarlatina, or epidemic diphtheria, that a transition from 

 croupous to diphtheritic inflammation is observable. Even here, too, 

 though the pharynx may be the seat of a most exquisite diphtheria, it is 

 far more common, and it is, in fact, the rule, for the laryngeal inflamma- 

 tion to retain the characteristics of true croup. (See chap. " Diphtheria.") 



Croup is of far rarer occurrence upon other mucous membranes than 

 upon those of the air-passages, and, during childhood, is almost ex- 

 clusively a disease of the trachea and larynx, rarely affecting the 

 alveoli of the lungs. On the other hand, croupous pneumonia, a true 

 croup of the air-cells, is one of the most common diseases of adults, in 

 whom primary croup of the trachea and larynx scarcely ever occurs. 



Although peculiarly a disease of childhood, still the disposition to it 

 is less during the period of suckling. After the second dentition, too, 

 the disease is more rare ; so that the period of greatest predisposition 

 for croup lies between the second and the seventh year of life. Boys 

 are more subject to it than girls ; but it is an error to suppose that vig- 

 orous, full-blooded, blooming children 'are especially liable. On the 

 contrary, tender, delicate, ill-nourished offspring of tuberculous parent- 

 age, with pale skin and conspicuous veins (an ominous sign even for the 



