Catarrhal croup should be distin guished from acute catarrhal laryngitis. The latter disease may be primary, sec ondary to the infectious diseases, or traumatic. The lesions are found chiefly in the mucosa and lymphoid tissue of the subglottic region, and in severe cases they may be so pronounced as to cause laryngeal stenosis. This disease is fre quently a complication of bronchitis. It is marked by hoarseness and a fre quent, harassing, metallic cough, which always becomes worse at night and is usually aggravated by lying down. The milder and more common cases are usu ally seen in children between one and six years. Although extremely annoy ing, they are rarely dangerous or fatal. A severe type is sometimes seen, how ever, which may prove fatal. In this type the temperature is high; the voice is metallic and ina.y be suppressed; laryn geal stenosis may become so great as to demand intubation. This disease is dif ferentiated from pseudomembranous lar yngitis with the greatest difficulty.
The disease may be mistaken for pseu domembranous croup, laryngismus strid ulus, and even pneumonia. The presence of foreign bodies in the larynx must be excluded, as well as retropharyngeal ab scess. The sudden onset, remission of symptoms, hoarseness without loss of voice, loud metallic cough, with little or no stridor, and the response to treat ment usually suffice to distinguish ca tarrhal croup from pseudomembranous croup, with its insidious onset; slower, but more steady and unremitting, course; suppressed voice and cough, increasing cyanosis, enabarrassed expiration, and characteristic stridor. Laryngitis strid ulus is a disease of early infancy. The symptoms occur in paroxysms, which are usually repeated many times a day and occur at no definite hour. They are un accompanied by any evidences of ca tarrh. The disease invariably occurs in rachitic infants, and is a frequent accom paniment of tetany or general convul sions.
Croup is increased by alternations of dry and moist air. It is not always possible to obtain a view of the glottis in cases of suspected croup; therefore we have often to rely on the presence Or absence of croupous exudate on the epiglottis, or on the tips of the aryte noids, for assistance in making a diag nosis. In one class of cases the cause of the stenosis lies only in the immobility and media,n situation of the vocal cords and the t-try-tenoid cartilages, which are held together by false membrane in the interarytenoid space. In another class the stenosis is influenced by swelling of the mucous membrane under the glottis.
Occasionally it is caused by the swelling under the glottis alone, the cartilages being normally movable; and in such cases the interarytenoid space is free from croupous exudate. Briihl and Fahr ("Diphtheria and Croup in Prussia from 1S75 to 1882").
The onset of non-bacillary croup is much more sudden than that of diph theria, and the temperature rises more quickly and to a higher point. The mem brane has not the dead-white appearance of diphtheritic membrane. It is yellow ish in color, softer, less firmly matted together, a.nd more easily detached from the underlying tissues. Placed in water, the membrane swells up, losing its char acteristic sha_pe. The surface from which the membrane has been detached is sell dom bleeding or ulcerated, and may preserve its epithelium quite intact. Ex-1 amined microscopically, the membrane is found to consist of pus-cells, leucocytes, and fibrin. J. O. Symes (Bristol Medico Chin Jour., Mar., 190-0).
I have twice been called in consulta tion to find broncho-pneumonia in young children in which, when dry, difficult cough combined with an unusual degree of expiratory dyspncea had been mis taken for croup.
Etiology.—Age is an important pre disposing cause of the disease, which i most common. between two and flys years. It is very rare under one yea and over eight. It may occur, however, at any time until adolescence, and I have seen a typical case in an adult.
Case of croup, with fatal termination observed in a, lady of 60 years, who ha. had several attacks of spasmodic crou at about 40 years of age. Waxham (No. Amer. Pract., Sept., '91).
Heredity is also an important predis posing cause, the disease occurring with especial frequency in some families. En larged tonsils and adenoid growths also predispose to croup. It is sometimes brought on, apparently, by atmospheric conditions, as it is not uncommon to see several cases at about the same time. It cannot, however, be called an epi demic disease. Exposure to cold is un doubtedly the most important and excit ing cause. Excessive use of the voice in damp and cold weather is, also, a fre quent cause. Indigestion will often, un doubtedly precipitate an attack in a sensitive child.
Pathology.—The lesions of catarrhal croup are found chiefly above the vocal cords and are those common to all ca tarrhal inflammations of the mucous sur faces. The spasmodic symptoms are due chiefly to spasm of the adductors. The disease may appear primarily in the larynx or it may extend from the naso pharynx downNvard or more rarely from the trachea upward.