LOCOMOTOR ATAXIA, a popular name for a disease of the nervous system, which is caused exclusively by syphilis, al though less than half of 1 per cent of those who have syphilis develop it, and usually occurs in adults from 40 to 50. It is characterized by pain, inability to walk and by progressive weak ness which leads finally to death. The malady is long drawn out, becoming serious sometimes as many as 40 or 50 years after the first in fection, and while not entailing, as a rule, a great amount of physical pain, causes extreme inconvenience to the patient. It is present in men more frequently than in women, because syphilis is more frequent in men. In the vast majority of patients it first shows itself by neuralgic pains of the lower extremities. Thus, there may be acute darting and lightning-like pains, lasting from half an hour to an hour or two, about the ankles, in the shooting up the leg or in the thighs. Occasionally these pains are present in the arms and trunk. They are frequently diagnosed as neuralgia, and it is not until development of the symptoms of ataxia (q.v.), a word which means ((inability to co-ordinate"— inability to walk in the dark and to place the foot or hand where the mind wishes it to be placed— that the true nature of the constant neuralgic pains is recognized. The patient finds himself insecure on uneven sur faces. He stumbles and falls, and must keep his eyes glued to his legs or the surface on which he is walking if he is to be able to con trol them. With the gradual development of the inability to walk there maybe a number of other symptoms — acute, lightning-like pains in the stomach, sometimes acute, pain in the bladder, sometimes loss of voice, etc. There may be patches of anaesthesia over the body and there is usually progressive muscular i weakness. Loss of knee-jerks is an important early sign.
Associated with ataxia of the legs, which prevents the patient from walking readily in the dark, or up and down stairs, there may be some ataxia in the hands, whereby the finer movements of buttoning the clothing, of writ ing, etc., may be interfered with, although there may be no loss in muscular strength un til the last stages of the disease. A very con stant and usually a very early sign of locomotor ataxia consists in certain changes in the reac tions of the pupil of the eye to light. This symptom is technically known as the Argyll Robertson pupil, and shows a fixed pupil when exposed to the influence of light, but a pupil that dilates or contracts normally when tested for its powers of accommodation. Thus in a patient who has this symptom the pupils con tract on looking at a near object and dilate on looking at a far object; but if a candle or beam of light is thrown suddenly on the eye, normal quick contraction of the pupil is dimin • ished or absent. The Argyll-Robertson pupil is sometimes •found as early as the neuralgias, and a diagnosis may often be made on that alone.
The progress of the disease is usually very slow; remissions occur, which give great hope to the patient and afford ample opportunities for all forms of charlatanism; but the final outcome is usually hopeless. Many conditions of the spinal cord are known in which some of the symptoms of locomotor ataxia are present, chronic neuritis from alcoholism being one. As many of these are recoverable, the diagnosis of locomotor ataxia is an extremely difficult one, and can be made only by the com petent specialist. Consult Jelliffe, White, 'Diseases of the Nervous System' (1917). See SYPHILIS OF THE NERVOUS SYSTEM ; TAsas DORSALIS.