The clinical features of the two diseases usually exhibit consider able diversity. Rheumatism seizes upon the larger joints of the ex tremities, either simultaneously or in quick succession. Gout usually begins in the joints of the great toe, and seldom quits the smaller articulations of the foot and hand. Rheumatism is less painful than gout; it is accompanied by less superficial inflammation and des quamation of the cuticle; though it may sometimes produce an equal amount of (edematous swelling about the affected part, it is never attended by the turgescence of the cutaneous veins that is so marked a feature during the gouty crisis. The symptoms that follow inva sion of the intracranial organ differ in the case of the two diseases. Headache is less severe and less characterized by lancinating pain in rheumatism than in gout. Aphasia and vertigo are rare events in the former disease, while they are not infrequent in the latter. In rheumatism, delirium, convulsions, and hyperthermia are commonly observed, though seldom witnessed in gout.
These characteristic and almost patliognomonic symptoms that so clearly distinguish the typical cases from each other are less sharply defined and convincing when we are called upon to deal with chronic, subacute, and masked forms of the two diseases. The slowly progres sive articular malady which has been described under the names of rheumatic gout, rheumatoid arthritis, or arthritis deformans, has many points of resemblance with senile gout. It was long an open question whether it is an independent pathological entity, or whether it is merely one of the varieties of chronic rheumatism or chronic gout. It is now considered as a separate disease, in which the mimicry of gout and rheumatism is more apparent than real; and in order to avoid confusion with the other species of diathetic arthritis, it seems expedient to omit from its nomenclature all reference to them, giving it the independent title of arthritis deformans. This form of arthritis is frequently hereditary—in this respect resembling gout. It usually occurs among elderly females, but without any previous influence of intemperance, indolence, or luxury. It is usu ally, on the contrary, associated with low living, austerity of manners, and laborious occupations, manifesting itself during the decline of life, and slowly progressing without any very evident exciting cause. The articular deformity presents an appearance that is like that of chronic osteitis combined with uratic deposits ; yet the urates are entirely absent, and the thickened tissue lies not only upon the tuber osities of the phalangeal joints but along the sheaths of the tendons and upon the sides of the bones of the fingers and toes. These no dosities are often obscurely movable, they contain no mineral mat ter, and in their histological structure they resemble fibromata. Yet, such may be the shape and deviation of the different joints that mere external inspection can with difficulty distinguish them from the moderately infiltrated and partially deformed articulations of chronic and torpid gout. Authors have also been somewhat divided regard
ing the classification of the so-called nodes of Heberden. Some have ranged them among the signs of gout, but with the majority they are considered as the result of chronic rheumatism. As an illustration of the difficulties that beset diagnosis by inspection of the affected joints, it is well to recall the fact that in certain apparently typical cases of arthritis deformans, post-1120)•m, examination has revealed the previously unsuspected presence of urates infiltrating the articula tions. Sometimes the little subcutaneous nodules that are so characteristic of gout are entirely absent in well-marked cases of the disease, so that their absence must not be permitted to argue too strongly in favor of the rheumatic origin of such cases. Again, it occasionally happens that, instead of attacking the smaller joints, gout invades the larger articulations with manifestations like those of chronic rheumatism.
In all these doubtful cases it becomes necessary to pass beyond the mere inspection of the affected members, and to make careful in quiry regarding the family history of the patient, his ancestors and relatives. The early life of the individual must be reviewed with ref erence to experience of the earlier evidences of the gouty diathesis, and the possible occurrence of premonitory or previous attacks of articular disease. The symptoms and course of such disorders must be carefully considered. The state of health during the intervals of apparent freedom from disease must also be ascertained.
In doubtful cases, Sir A. Garrod advised the examination of the blood, or of the serum of a blister, in order to determine the presence or absence of uric acid. The serum of blood that has been drawn at a distance from the seat of active inflammation is to be preferred, be cause urates are not found iu the blood that is taken from the vicinity of an affected joint. Blood serum is also to be preferred to the serous fluid from a blister, because the latter contains a smaller number of leucocytes that might conceal the crystals of uric acid. The serum should be placed in a watch-crystal, and be acidulated with five or six drops of ordinary acetic acid. A few separate fibres of linen are then placed in the serum, and the whole is permitted to evaporate for twenty-four hours at a temperature below 70° F., until the liquid has nearly dried away. Placing the fibres under a microscope, they will be seen covered with the crystals of uric acid, if the patient be gouty. In the vast majority of eases this test will be sufficiently de cisive; but occasionally the blood of a genuine gouty subject, whose joints are crippled by uratic deposits, will contain no uric acid. Again, the test cannot be expected to succeed in merely diathetic cases that have never reached the stage of articular manifestations. Bearing these facts in mind, Garrod's test may be accepted as a valu able contribution to the means of diagnosis in obscure forms of the disease.