A system of practical medicine. By American authors. Vol. 3

by Unknown

Following the increased frequency of the heart's action, after a variable period enlargement of the thyroid body occurs. The enlargement may be rapid, but in most cases it takes place slowly, and ceases when it has reached a moderate degree. Cases are exceptional in which the degree of enlargement is such as to occasion any obstruction to respiration. Almost invariably both lobes of the thyroid body are enlarged, but the enlargement is generally not equal on the two sides, and, as a rule, it is greater on the right side. The enlarged lobes are soft at first, afterward becoming hard. The subcutaneous veins over them are often distended. Pulsation of their arteries is apparent to the hand and to the eye. A systolic arterial blowing murmur and a continuous hum are heard when the thyroid region is auscultated. In some instances the murmur is like that of an aneurismal varix. As a rule, murmurs are heard over the carotid artery and the jugular vein. A thrill or fremitus is often felt by the hand placed upon the thyroid body. The thyroid enlargement is due at first chiefly to dilatation of the arteries and veins. Hyperplasia of the fibroid tissue occurs afterward, and then the enlarged gland becomes hard to the touch. The size of the enlarged thyroid body is often found to vary considerably at different times—a fact attributable to varying degrees of the dilatation of the vessels and of the consequent hyperæmia.

A notable protuberance of the eyeballs has sometimes been observed to take place suddenly, but, as a rule, it is at first slight and increases slowly. The degree of protuberance varies considerably in different cases. When marked, the patient has a remarkable staring expression. Both eyeballs are alike protuberant with very rare exceptions.⁸ The pupils are unaffected and vision is not impaired. The protuberance is sometimes so great that the globes cannot be covered by the eyelids. Under these circumstances inflammation of the conjunctiva ensues, and perforation of the cornea has been known to occur. The eyeballs can be pressed backward into the sockets without a degree of force which occasions pain, but the protuberance returns directly the pressure is discontinued. In most, but not in all, cases the consensual movements of the upper eyelid and the globe, when the latter is moved upward or downward, are impaired; that is, the movements of the lids do not follow those of the globes. That this symptom is not to be accounted for by the exophthalmia is shown by the fact that it is not a symptom when the protuberance of the eyeball is caused by an intra-orbital tumor. The symptom therefore has diagnostic significance. The ophthalmoscope shows the veins of the retina to be dilated and tortuous, with, in some instances, visible pulsation of the retinal arteries. Anatomical conditions to which the exophthalmia is, in a measure at least, referable, are enlargement of the intra-orbital vessels by hyperæmia and an increased amount of post-ocular fat. Paresis of the straight muscles, induced by stretching, is probably an important factor when the protuberance is great. These muscles have in some instances been found to have undergone fatty degeneration.

⁸ Allan McLane Hamilton, in his work on Nervous Diseases, cites a case reported by Yeo, in which the exophthalmia effected only the left eye, and the goitre was limited to the right thyroid body. Cases of unilateral goitre with bilateral exophthalmia have been observed.

Anæmia is usually associated with the foregoing cardinal symptoms. It is sometimes wanting. This was true of a case recently under my observation. If anæmia does not exist, the blood-murmurs referable to the heart and vascular system may be absent. If anæmia exist in a marked degree, there are present certain symptomatic phenomena referable thereto—namely, neuralgic pains in different situations, want of physical and mental endurance, hysterical manifestations, depression of spirits, etc. Mental irritability is apt to be a prominent trait of the affection. This may in a great measure be referred to sensitiveness occasioned by the exophthalmia. Owing to this, patients often avoid observation as much as possible. They naturally, women especially, are led to brood over the calamity of such a singular and conspicuous deformity. Breathlessness on exercise is a symptom more or less marked according to the increase in the frequency of the heart's action and the impoverishment of the blood. The appetite and digestion may or may not be impaired, and hence there may or may not be emaciation. It cannot be said that the affection is accompanied by fever, although in a certain proportion of cases the temperature of the body is half a degree or a degree above the normal range. Reports of cases embrace a considerable number of concurrent symptoms which are occasionally present, such as cephalalgia, insomnia, vertigo, amenorrhoea, neuralgia, unilateral sweating, etc. These have no special connection with the affection, but are incident to associated pathological conditions.

DIAGNOSIS.—The three phenomena which distinguish this affection are so obvious as well as characteristic that a diagnosis cannot well be avoided, after a description derived from books or lectures, when the first case presents itself in practice. The wonder is that the affection had not been clearly pointed out prior to the writings of Graves and Parry. Any difficulty in diagnosis relates to cases in which either the exophthalmia or the enlargement of the thyroid body is wanting, or to the incipiency of the affection when its characteristics are not fully developed. The bilateral protuberance of the eyeballs, the absence of local symptoms other than those caused by the exposure of the conjunctiva when the eyelids fail to cover the globes, the mobility and normal size of the pupils, the want of the normal consensus in the movements of the eyelids and the globes, and the replacement of the latter by moderate pressure, are the diagnostic points which distinguish the exophthalmia in this affection from that incident to intra-orbital tumor. The moderate increase of the thyroid body, its softness to the touch, its notable variations in volume at different times, its pulsation and the auscultatory murmurs which it generally furnishes, are diagnostic points distinguishing the enlargement in this affection from that of bronchocele. The persistent frequency of the heart's action is not less marked when either of the two phenomena just referred to is wanting than when both are present. The degree of frequency varies, but more or less increase is a constant symptom; and it is a symptom not likely to be present in either exophthalmia or in goitre unassociated with Graves' disease.

Aside from the symptomatic triad, the clinical history offers in different cases considerable diversity. The diverse inconstant symptoms as they occur in other pathological conditions are without diagnostic significance. A large proportion are incident to the anæmia so often associated with the affection under consideration.

PATHOLOGY AND ETIOLOGY.—Inasmuch as the persistent frequency of the heart's action is the first event in the order of time, the thyroid enlargement and the protuberance of the eyeballs being epiphenomena, it seemed a rational supposition that the latter events were dependent on the cardiac disorder. This view was held by Graves and his colleague, Stokes. A supposition much more rational is that the three events are united by a common causation. Anæmia has been supposed to be the causative condition. This supposition is disproved by the fact that anæmia does not exist in all cases. Moreover, anæmia is a pathological condition of frequent occurrence, whereas the affection under consideration is extremely rare. It is, however, very probable that anæmia may play an important auxiliary part in the causation, as it does in all the neuroses. With the knowledge of the sympathetic and vaso-motor nerves which has been acquired since the date of Graves' discovery, the pathology seems clearly to involve these components of the nervous system. This pathological view is perhaps generally held at the present time. But to interpret all the phenomena satisfactorily by reference to the known functions of these nerves is not easy. Vaso-motor paresis will account for the dilatation of the vessels, which is an important anatomical element in the enlargement of the thyroid body and the exophthalmia. On the other hand, acceleration of the heart's action is not an effect of paresis, but of excitation. To account for this incongruity there have been different hypotheses, which it does not fall within the scope of this article to discuss. Some autopsies have shown anatomical changes in the cervical sympathetic and its ganglia, but in others no morbid appearances have been found. Whether the pathology involves peripheral nerves alone or a central morbid condition in the spinal cord or the medulla oblongata is an undecided question. For facts and arguments bearing on the different points of inquiry relating to the pathological seat and character of the affection the reader is referred to other works.⁹ I will only add that in view of the fact of the exophthalmia and the goitre being, in the vast majority of cases, bilateral, it seems rational to suppose the pathological nervous condition to be central rather than peripheral. This is assuming that the three cardinal events involve a common causative condition, and not that the exophthalmia and goitre are dependent on the cardiac disorder. The termination in a certain proportion of cases in recovery goes to show that the affection does not necessarily involve structural lesions, and hence that it is properly included among the neuroses. The constancy and prominence of the disordered action of the heart render it proper to consider the affection in connection with the neuroses of that organ.

⁹ For a résumé, vide article by Eulenburg in Ziemssen's Cyclopædia, vol. xiv.

In the etiology of Graves' disease sex and age have a decided influence. In very much the larger proportion of cases the patients are women. The proportion of 2 to 1, which is stated by some writers, is not sufficiently large. Out of 20 or more cases which have fallen under my observation, in 1 only was the patient of the male sex. The disease is extremely rare under puberty and after middle age. Between these extremes of age there is no special predilection of the disease for any particular period of life.

Of causes which are independent of sex and age we have no positive knowledge. In particular cases the disease has been attributed to traumatic causes, to fright or other kinds of mental excitement, to sexual excess, etc. The evidence of a causative relation in these cases is simply a post-hoc connection which obtains in but a single instance or at most in a few instances. Etiological speculations, in the absence of ascertained facts, are, to say the least, useless, and it is the most politic as well as the fairest statement to say that in the present state of our knowledge we have no adequate data for determining the causation of the affection.