Another nervous disease, corresponding in some of its features to paresis and indeed sometimes spoken of as a spinal form of paresis, is locomotor ataxia. This affection {321} begins usually with loss of sensation in the soles of the feet so that the patient thinks that he is walking on carpet all the time. Before this there may have been some disturbance of vision. The pupils may fail to react to light. Occasionally the first symptoms are motor, that is, the man notices that he is not able to walk as readily as before. He staggers easily. If he tries to turn round while walking he is apt to lose his balance. If he tries to walk in the dark, he is almost sure to have so great a sense of insecurity that he dare not go far from the wall. Occasionally the first sign is a sinking of the limbs on the way down stairs. In certain very sad cases, the first and only symptom is a failure of sight which goes on progressively, until the optic nerve is completely destroyed and sight forever rendered impossible. All these symptoms are traceable directly to certain changes which have been noted in the spinal cord. These changes are due to disturbance of the blood and lymph supply of the nervous tissue. Once the changes have taken place, there is no hope of the patient ever recovering the normal use of his limbs. Not infrequently he becomes bedridden and can not walk at all because he is not able to steady himself. He may not suffer in his general health, however, to any serious extent, and may live on for twenty years, though usually his resistive vitality is lowered and he is carried off by some intercurrent disease. At times locomotor ataxia begins with very severe pain seizures, known as crises. These may occur in the legs or arms or in the stomach or sometimes in other organs. Occasionally they are the first symptoms of the disease that are noticed, and they may continue for months or even years before other symptoms manifest themselves. This sometimes makes it difficult to recognise the disease for what it really is. The pains are usually most excruciating, are tearing or boring in character, and are sometimes described by the patient as being similar to the sensation that would be felt if a red hot iron were forced into them, or if a knife were inserted and then twisted round. Hence the descriptive name which has been applied to them of "lightning pains" which describes the suddenness of their onset and the intensity of their character. {322} Most of the ordinary anodyne or pain-killing medicines fall to influence them, and the patient is one of the most pitiable of objects while they last.