6. The existence of, any other disease within the larynx or trachea. Any of these latter may be present in the adult or the child indif ferently.
Few diseases have attracted more attention than the spasmodic croup of children ; few have been more accurately described as to symptoms, and in none is our pathological in formation more deficient; a fact that may al most be proved by the number of different names by which it has been designated. It is the asthma of infants of Millar; the cerebral croup of Pretty; the spasm of the glottis of Marsh ; the spasmodic croup of other writers ; and the laryngismus stridulus of Mason Good and Ley. It occurs in very young children, with a peculiar difficulty of breathing, attack ing for the most part suddenly, accompanied by a crowing sound, and oftentimes with a sus pension of respiration for several seconds. This difficulty of respiration varies in intensity from a single crow to a more prolonged paro xysm threatening suffocation, and terminates when in recovery by a long deep-drawn respi ration, with a peculiar stridulous noise; when in death, by such convulsive struggles as might lead, and indeed have led, to a belief that the cerebrum was engaged. Pallid and exhausted, the child falls lifeless upon the nurse's arm, and is then generally said to have died in a fit. In these cases there is no cough ; no raucal sound of voice; no continued stridulous breathing, except an occasional mucous rattle heard only while the infant sleeps be con sidered as such ; there is no fever ; and on ex amination after death no trace of inflammation, nor indeed any deviation from the ordinary healthy appearance of the organ, can be disco vered. Under these circumstances, patholo gists had no method of explaining the pheno mena but by spasm, an irregular and invo luntary contraction of the muscles of the larynx closing up the rima glottidis to a greater or less extent, and in proportion to such Closure in terfering with and obstructing respiration.
But what is the cause of this spasm ? Some have supposed it to have an intimate con nexion with an hydrocephalic tendency, be cause it has been sometimes seen in children with large heads and sluggish dispositions, and because signs of cerebral congestion have been discovered after death ; but I have seen the di sease prove fatal to the liveliest and apparently most healthy children, and the congestion may just as well be the consequence as the cause of the closure of the glottis. Others again have referred it to the general constitutional irri tation that proceeds from painful dentition, and doubtless cases have occurred in which the crowing respiration was relieved by successive scarifications of the gums, according as each tooth became prominent underneath ; but this, although teaching an important practical lesson, leaves the pathological connexion between the facts in as much obscurity as ever. Accord ing to others there is a constitutional tendency to this disease in some children, a fact which it must be conceded has been painfully exempli fied in more families than one ; but this here ditary disposition to disease, although abun dantly obvious, is too imperfectly understood to be discussed with any thing approaching to pathological accuracy. Lastly, improper or un wholesome food, indifferent clothing, a close and tainted atmosphere, and exposure to vicis situdes of climate, have been regarded as in fluential exciting causes, and change of circum stances in these respects has often produced an almost magical amendment in the condition of our little patients ; but still we are at a loss to discover the immediate modus operandi of these pernicious influences, or why they should be determined to the larynx in the form of an i voluntary spastic contraction of its muscles.
Other causes have been assigned for the p duction of this disease, some of which are eminently deserving of attention ; at the same time it may be observed that its being attri buted to such a number of influences shews that its real exciting cause is probably still unknown. For instance, either this disease or an affection bearing a strong resemblance to it, has been described by Dr. Kopp, and after wards by Dr. IIirsch of Kiinigsberg, under the name of thymic asthma, and by them attri buted to an hypertrophied condition of the thymus gland, which by its weight and volume presses on the heart, the lungs, the large arte rial and venous vessels, and prevents the free exercise of their functions. Dr. Montgomery has published an interesting paper on this sub ject, in which he attributes the sudden death to an enlargement of this gland, whether that arises from hypertrophy of its substance or an alteration of its structure from scrofula or other disease; and explains how agitation or excite ment may suddenly distend and increase the size of the organ in such a manner as to affect materially the condition of the surrounding parts. Again, in the work by Dr. Ley already referred to, a different explanation has been offered. Apparently relying on the experi mental researches of Magendie and Le Gallois, lie supposes that, if the recurrent nerves are compressed to such an extent as to have their functions impaired, the glottis, under the in fluence of the superior laryngeal branches, would become and continue fast closed. The cause of the disease then, according to him, will be found in some tumour, scrofulous or otherwise, so situated as to create an injurious degree of compression on the recurrent nerves. That an enlargement of the thymus gland may, from its situation, produce great and serious in convenience, it would be absurd to question, and perhaps there is sufficient evidence to skew that it may occasion the symptoms and results of this very disease : but it is far from being proved that spasm of the glottis may not occur, and even prove fatal in cases where no such enlargement existed. Alterations of size, shape, and structure, even if rapid, take place gradu ally, and their results should be gradual also, whereas this disease has been known to destroy its victim in its first and only paroxysm ; and moreover, if structural change in the gland was its sole exciting cause, it would be difficult to account for its sudden disappearance on the removal of the child to the country and its diet being changed. Whilst therefore it may not be denied that hypertrophy of the thymus can occasion the phenomena by others attributed to spasm of the glottis, there is not sufficient proof of its,being the general or even frequent cause of this peculiar disease. I shall have 1 occasion to notice the supposed consequences I of pressure on the recurrent nerves hereafter.