LOCOMOTOR ATAXY, (a priv., _____, order-—Syno-nyms, Progressive locomotor ataxy, Tabes dorsalis, Posterior spinal sclerosis), a disease of the nervous system, manifest-ing itself principally by disordered movements of the limbs in locomotion. This disorder is not, as was once supposed, a form of paralysis (there being no diminution of muscular strength), but is dependent on the loss of the power of co-ordinating the muscles into harmonious action, which is essential to the proper performance of the voluntary move-ments of the body, and the maintenance of its equilibrium. Although the disease had been previously noticed both by Professor Romberg and Dr R. B. Todd, it was first fully described and named by Dr Duchenne in 1858. Its path-ology has subsequently been investigated by Mr Lockhart Clarke. Locomotor ataxy usually begins insidiously, and advances slowly. Among the earlier symptoms observed are disorders of vision, with occasionally temporary or per-manent paralysis of some of the cranial nerves, a feeling of uneasiness in the back, accompanied with violent shooting pains down the limbs, increased or perverted sensibility in various parts of the body, and disturbance of the genito-urinary functions. These initial symptoms may continue without much change for a long period, but generally in the course of time others are superadded, which give more definite intimation of the existence of the disease, and render its diagnosis a matter of little difficulty. The sufferer begins to be aware that he cannot walk with the same freedom as before, and he feels as if some soft sub-stance were interposed between his feet and the ground. His gait assumes a peculiar and characteristic appearance. He begins the act of walking with evident difficulty, and his steps are short and hurried. Each leg is lifted well from the ground; but as he moves forward it is thrown out from him, and his heel descends forcibly, and is followed at a longer than the normal interval by the sole. In walking he requires the aid of his vision to preserve his equilibrium, and he therefore looks at his feet, or rather at the ground a little in front of them, as he advances. He cannot turn about suddenly without the risk of falling. If asked to stand erect with his feet approximated, and then directed to close his eyes or to look upwards, he immediately begins to sway and totter, and would fall if not supported. These various phenomena are the result, not of any weakness of motor power, but simply of defective muscular co-ordina-tion. Along with this there usually exists markedly diminished tactile and cutaneous sensibility, particularly in the feet and legs. Sometimes the disorder implicates the upper extremities, and then the hands and fingers cease to perform their functions with precision, so that the patient is unable to pick up any small object from the ground, to button or unbutton his clothing, and even sometimes to feed himself, although at the same time there is no weakness in the muscular power of the hand, which is capable of grasp-ing as firmly as before. With the advance of the disease the disorder of movements increases. The patient's efforts to walk become more and more difficult and distressing, for his limbs are jerked about wildly without restraint, while even the aid of his vision and the support of a stick are insufficient to prevent him from falling. Ultimately, all efforts of this kind have to be abandoned, and he is com-pelled to lie in bed. In the later stages of the disease all the symptoms become aggravated. The shooting pains and violent jerkings of the limbs increase, motor power becomes impaired, and the patient sinks under the pro-longed and exhausting course of suffering, or dies from some intercurrent disease. Although usually progressive to a fatal termination, locomotor ataxy is sometimes arrested, and even appears occasionally to be recovered from, particularly in its earlier stages. In most instances its duration extends over a number of years.

The pathological condition giving rise to locomotor ataxy is disease of a certain portion of the spinal cord, viz., the posterior columns and the posterior nerve roots. These undergo various transformations, which result in their ultimately becoming atrophied and indurated. When affecting, as this lesion most commonly does, the lower dorsal and lumbar regions of the cord, the ataxic symptoms are chiefly confined to the legs; but when it affects the cervical portion, the arms are involved. Occasionally the whole posterior columns of the cord are found diseased. The exciting causes of this malady are but ill understood. Exposure to cold and privation, intemperance, over exertion, and mental anxiety have been supposed to give rise to it. In some instances the disease appears to be hereditary. Locomotor ataxy is much more common among men than among women. It is a disease of middle life, being most frequently observed to occur between the ages of 30 and 50. From the nature of the structural changes affecting the spinal cord in locomotor ataxy, it is evident that, beyond the employment of means to alleviate the various painful symptoms, little can be done towards its cure. Numerous medicines have from time to time been brought forward as supposed to possess special efficacy in the treatment of this disease, but none of them have proved to be of much value. The employment of electricity in the form of the continuous current has been recommended by many high authorities. Probably most good will be found to result from careful efforts to maintain the general health by a well-appointed diet and regimen. (J. O. A.)