In Lesions of Peripheral Nerves.—In the hand, and more rarely in the foot, when one or other of the main nerve-trunks has been divided or compressed, the joints may become swollen and painful and afterwards become stiff and deformed. Bony ankylosis has been observed.
In Affections of the Spinal Medulla.—In myelitis, progressive muscular atrophy, poliomyelitis, insular sclerosis, and in traumatic lesions, joint affections are occasionally met with.
The occurrence of joint lesions in locomotor ataxia (tabes dorsalis) was first described by Charcot in 1868—hence the term “Charcot's disease” applied to them. Although they usually develop in the ataxic stage, one or more years after the initial spinal symptoms, they may appear before there is any evidence of tabes. The onset is frequently determined by some injury. The joints of the lower extremity are most commonly affected, and the disease is bilateral in a considerable proportion of cases—both knees or both hips, for instance, being implicated.
Among the theories suggested in explanation of these arthropathies the most recent is that by Babinski and Barré, which traces the condition to vascular lesions of a syphilitic type in the articular arteries.
The first symptom is usually a swelling of the joint and its vicinity. There is no redness or heat and no pain on movement. The peri-articular swelling, unlike ordinary œdema, scarcely pits even on firm pressure.
In mild cases this condition of affairs may persist for months; in severe cases destructive changes ensue with remarkable rapidity. The joint becomes enormously swollen, loses its normal contour, and the ends of the bones become irregularly deformed (Fig. 162). Sometimes, and especially in the knee, the clinical features are those of an enormous hydrops with fibrinous and other loose bodies and hypertrophied fringes—and great œdema of the peri-articular tissues (Fig. 163). The joint is wobbly or flail-like from stretching and destruction of the controlling ligaments, and is devoid of sensation. In other cases, wearing down and total disappearance of the ends of the bones is the prominent feature, attended with flail-like movements and with coarse grating. Dislocation is observed chiefly at the hip, and is rather a gross displacement with unnatural mobility than a typical dislocation, and it is usually possible to move the bones freely upon one another and to reduce the displacement. A striking feature is the extensive formation of new bone in the capsular ligament and surrounding muscles. The enormous swelling and its rapid development may suggest the growth of a malignant tumour. The most useful factor in diagnosis is the entire absence of pain, of tenderness, and of common sensibility. The freedom with which a tabetic patient will allow his disorganised joint to be handled requires to be seen to be appreciated.
The rapidity of the destructive changes in certain cases of tabes, and the entire absence of joint lesions in others, would favour the view that special parts of the spinal medulla must be implicated in the former group.
In syringomyelia, joint affections (gliomatous arthropathies) are more frequent than in tabes, and they usually involve the upper extremity in correspondence with the seat of the spinal lesion, which usually affects the lower cervical and upper thoracic segments. Except that the joint disease is seldom symmetrical, it closely resembles the arthropathy of tabes. The completeness of the analgesia of the articular structures and of the overlying soft parts is illustrated by the fact that in one case the patient himself was in the habit of letting out the fluid from his elbow with the aid of a pair of scissors, and that in another the joint was painlessly excised without an anęsthetic.
The disease may become arrested or may go on to complete disorganisation; suppuration may ensue from infection through a breach of the surface, and in rare cases the joint has become the seat of tuberculosis.
Treatment, in addition to that of the nerve lesion underlying the arthropathy, consists in supporting and protecting the joint by means of bandages, splints, and other apparatus. In the lower extremity, the use of crutches is helpful in taking the strain off the affected limb. When there is much distension of the joint, considerable relief follows upon withdrawal of fluid. The best possible result being rigid ankylosis in a good position, it may be advisable to bring this about artificially by arthrodesis or resection. Operation is indicated when only one joint is affected and when the cord lesion is such as will permit of the patient using the limb. The wounds heal well, but the victims of tabes are unfavourable subjects for operative interference, on account of their liability to intercurrent complications. When the limb is quite useless, amputation may be the best course.
In cerebral lesions attended with hemiplegia, joint affections, characterised by evanescent pain, redness, and swelling, are occasionally met with. The secondary changes in joints which are the seat of paralytic contracture are considered with the surgery of the Extremities.
In cases of hysteria and other functional affections of the nervous system, an intermittent neuropathic hydrops has been observed—especially in the knee. Without apparent cause, the joint fills with fluid and its movements become restricted, and after from two to eight days the swelling subsides and the joint returns to normal. A remarkable feature of the condition is that the effusion into the joint recurs at regular intervals, it may be over a period of years. Psychic conditions have been known to induce attacks, and sometimes to abort them or even to cause their disappearance. Hence it has been recommended that treatment by suggestion should be employed along with tonic doses of quinine and arsenic.