of the nervous system. Instances of this are-father epileptic; father insane; two sisters insane. Direct inheritance of the disease is extremely rare (the special hereditary form being always excluded). A boy with distinct symptoms and optic nerve atrophy was the son of a man who presented characteristic indications of the early stage of tabes (Remak). But in most instances of this character the inheritance is effected by means of syphilis.

Males suffer far more frequently than females, the proportion being about ten to one, and this implies some proclivity inherent in the male sex. A like preponderance of males obtains in a disease that has some alliances with tabes-general paralysis of the insane. The middle period of adult life is that in which locomotor ataxy usually commences. No less than half the cases begin between thirty and forty, one quarter between forty and fifty, and rather less than a quarter between twenty and thirty. It rarely begins after fifty, but I have once known it to develop at sixty-six. Under twenty it is still more rare, but cases are met with as early as ten, and even in quite young children, the subjects of the cause next described.

Among the individual causes, one overshadows all the rest-the influence of syphilis. A very large proportion of the sufferers have had, at some previous time, constitutional syphilis, either distinct secondary symptoms or an indurated sore. The proportion is almost as large in the upper and middle classes as in the lower. Of fifty consecutive cases of the disease in men, seen in private consulting practice, no less than twenty-nine, or 58 per cent., gave a history of a chancre known to be hard, or of secondary symptoms; and eight others had had a venereal sore of unknown nature. In the lower classes the proportion is higher, and has been estimated at 80 per cent., or even more. The ascertainable facts are certainly below the real facts, as I have pointed out elsewhere.* When a deduction is made for possible accidental coincidence, there remains at least one half of the cases in which numerical coincidence must depend on causal relationship. It is probable, indeed, that, taking all cases, a causal proportion of three quarters would be nearer the truth. In women also antecedent syphilis can often be traced, although rather less frequently than in men. At the same time the facts are even more difficult to ascertain, since in married women syphilis so often runs a latent course. But in the cases of tabes that succeed syphilis the lesion is not syphilitic in histological character; it is as degenerative as in the cases in which syphilis can be excluded, and it is not influenced by the treatment for syphilis. Hence it must be regarded as a degenerative sequel of syphilis rather than as a true syphilitic disease. It is probably the influence of syphilis that determines the greater incidence on the urban than on the rural population, and the preponderance of cases in middle life. Inherited syphilis is also capable of causing the disease, and is to be traced in all cases in children. After the acquired disease the interval

Lettsomian Lectures,' 1889.

between primary syphilis and the first symptoms of tabes varies from one to twenty years. It is, however, rarely less than three years, and in most cases it is between six and twelve years. In rare cases the first symptoms occur during the active stage of syphilis.

It is certain, however, that syphilis is not the only cause of the disease. In a few cases, less than 10 per cent. of the whole, it can be excluded with confidence. The causes operative in these can be traced also in some of the patients who present a history of syphilis, and in such cases the causation of the malady is probably complex.

One of these causes, which can sometimes be clearly traced, is injury, such as involves concussion of the spine. The immediate results of the injury, whether slight or grave, transient or lasting, are followed by the symptoms of the degenerative malady. In one case a man fell from a height on to the deck of a ship; transient paraplegia resulted, but six weeks after the accident the man presented extreme ataxy, with good power, and no knee-jerk (Arnold). I have known the symptoms to develop gradually a few months after a fall from a horse. Exposure to cold and wet has occasionally preceded the onset so directly that it must be regarded as a cause. In other cases the disease has succeeded excessive fatigue and over-exertion, and also certain acute diseases, especially (it is said) acute rheumatism and typhoid fever; it follows diphtheria in rare cases, but the ataxic form of diphtheritic paralysis, passing away, is far more common than true tabes. (See also section on Pathology.) Alcoholic excess has been noted in some instances, and the influence of this cause is intelligible since it is known to cause sometimes such a form of porpital neuritis as occurs in tabes. Indeed, it is strange that this cause cannot be traced more frequently. Sexual excess has been supposed, by some, to be a cause; but its influence can rarely be detected, and its signi

Although an occasional relation to syphilis had been noted by several preceding observers, Fournier was the first (in 1876) to assert the wide extent of this relation. His statements were received with doubt (because syphilitic patients constituted his field for observation), but they were confirmed from the neurological side by myself (British Med. Journal,' March 1, 1879) and Erb (Arch. f. klin. Med.,' July, 1879); while abundant corroboration has been since afforded. Many who at first doubted have been convinced by fresh observations. Facts collected without reference to the point at issue have proved useless, and freshly collected facts have thrown a new light on the subject. The proportion of cases with previous syphilis necessarily varies according to the absolute frequency of syphilis, because the number due to other causes will be the same. Syphilis is rare among Hebrews, and hence a smaller ratio of Jewish tabetics have had syphilis. The difference in the character of the lesion from that of changes known to be syphilitic was urged as an objection by many writers, but such considerations are theoretical, and must yield to facts; instead of denying that this or that lesion can be produced by a given cause, we may have to widen our view of the operation of that cause. Other degenerations of the nervous system seem also to have a relation to syphilis, as I pointed out some years ago (Lancet,' Jan. 15, 1881). As will be shown in the section on Pathology, recent discoveries lessen very much the difficulty of comprehending the relationship.

ficance is uncertain, since sexual excitement is undoubtedly sometimes an early symptom of the disease.

Secondary Tabes.-Symptoms of locomotor ataxy sometimes succeed other diseases of the spinal cord, and such sequence is especially common in syphilitic subjects. Myelitis and syphilitic gummata may be thus succeeded by tabes. An officer in India, who had had syphilis, having suffered for a day or two from pains in the back, took a bath in snow water, and in a few days his legs were absolutely powerless. He gradually recovered power, but could not co-ordinate the movement: as power returned, lightning pains came on, and a year afterwards he presented the typical condition of locomotor ataxy. Again, a man, twelve years after syphilis, had a severe fall, followed by gradual loss of power, so that at the end of three weeks he could scarcely stand. The legs remained weak for a month, and then improved, but ataxy came on; three months later, power was good, incoordination extreme. A similar succession may occasionally be observed in those who have not had syphilis. In many cases, however, the ultimate condition is one of combined weakness and ataxy.

SYMPTOMS.-A typical case of developed tabes presents certain motor, sensory, and reflex symptoms. There is inco-ordination of movement of the legs, sometimes of the arms also, without loss of power or muscular wasting. There are pains in the affected parts, especially sharp momentary "lightning" pains; there is some loss of sensation; there is often loss or diminution of reflex action from the skin, and almost always entire loss of the myotatic irritability that is revealed by the so-called "tendon-reflexes," and especially by the kneejerk; there may be retention or incontinence of urine, constipation, and often loss of sexual power. Of this group of symptoms, two usually precede the others—the pains, and the loss of the knee-jerk. These may exist alone, even for years, before inco-ordination comes on. Thus the symptoms are far wider in range than the name "ataxy" suggests; and while inco-ordination, if it exists, is the most obtrusive objective symptom, it may never be developed. Hence physicians have extensively fallen back on the older term tabes dorsalis." But recent expansion of our knowledge, especially the discovery of the extent to which the symptoms may depend on disease of the peripheral nerves, shows that even the qualifying "dorsalis narrows the name unduly, and "peripheral neuro-tabes" has been added to the terminology of the disease.

Besides the symptoms above enumerated, others are occasionally present. Of these the most important are atrophy of the optic nerve (and occasionally of other cranial nerves); trophic changes in the skin, the bones, and the joints; peculiar paroxysmal visceral disturbances and occasionally motor paralyses and muscular wasting supervene. The combinations of symptoms present in different cases vary much. It will be convenient to consider first the individual symptoms in their various degrees, and then their grouping and sequence.

VOL. I.

26

Motor Symptoms.—The characteristic inco-ordination of movement develops gradually. It is usually increased (as Romberg pointed out) by closure of the eyes, and at first may only exist when the guiding influence of vision is thus withdrawn. Before it causes ataxy of movement, it may render difficult the maintenance of equilibrium when the base of support is narrowed by the feet being placed close together, toes and heels; if then the eyes are closed, the patient sways, and tends to fall. In health slight unsteadiness is thus produced, varying in degree in different persons, but never amounting to even a suggestion of a fall. The effect of closure of the eyes is greatest when sensation in the soles of the feet is defective, but does not depend on this defect; it may be marked when sensation on the soles of the feet is perfect. The early defect in co-ordination may be discovered by the patient when he walks in the dark, or backwards, or, not uncommonly, when he shuts his eyes in the process of washing the face. In a further degree of inco-ordination there is inability to stand with the feet together, even when the eyes are open, and the patient is only steady when the feet are wide apart. If the feet are bare, the diffi culty is greater, because muscular action has to replace the rigid basc of the boot. The irregular contraction of the muscles is shown by the conspicuous movement of the tendons on the back of the feet. The patient may oscillate from toes to heels before he comes to rest. As the defect progresses, uncertainty is felt in walking even with full visual guidance, especially on uneven ground, or on a very smooth surface. A slight visible alteration in gait is then appreciable, the feet are not placed on the ground quite as in health, or there is distinct difficulty in maintaining equilibrium when the patient turns quickly, and he has to put a foot down suddenly to keep from falling. As the inco-ordination increases, the change in gait becomes greater, but varies much in its precise characters, according to the muscles that are most affected. Often the feet are raised too high, thrown forwards too far, brought down too suddenly, and the whole sole comes in contact with the ground at once. There may be a tendency for one foot to be brought in front of the other, or moved too far outwards. Often the foot becomes inverted when it touches the ground. Efforts to correct error in movement have themselves to be corrected. other cases the defect in maintaining equilibrium is greater than the actual disorder of movement of the legs, and the patient sways about in the manner of one who has cerebellar disease; this probably depends on a preponderant affection of the muscles of the hip-joint.

In

As the defect progresses, the patient is only able to walk by steadying himself with a stick, or by taking hold of the arm of another person or of adjacent objects. At first a very slight degree of this help is sufficient; guidance rather than support is needed. Afterwards, however, considerable support is necessary, and ultimately the patient. may be unable to stand even with help. When he attempts to rise, the legs move hurriedly forwards and backwards, and if the upright

posture is at last achieved, the legs slip forward, and only strong support saves the patient from a fall. The ataxy is manifest also in other movements of the legs. If the patient, when lying, tries to touch an object with his foot, the leg is moved irregularly, goes beyond the place, and then is brought too far back, and only at last does it come in contact with the object, often with unintended force. This inco-ordination, like that in standing, is much greater if the eyes are closed.

The arms may present similar inco-ordination, although they often escape, even when the affection of the legs is extreme; very rarely the arms suffer before the legs. The commencing defect is revealed by delicate movements, such as writing. When slight, it may be conspicuous if the patient tries, with closed eyes, to touch some object, such as his own nose, or, having abducted his arms, tries to bring the forefingers together. As it increases, all movements become irregular; it is impossible for the patient to button his coat, or to pick up a small object from the table; the fingers twist about in the attempt. The grasp is not sustained; first one finger is felt to relax and then another. If the patient attempts to hold out his hand in a fixed posture, it is seen that the same irregularity obtains; instead of a uniform balanced contraction the muscs contract and relax involuntarily, and slow unintended movements of the fingers result, sometimes closely resembling those of athetosis. The same spontaneous movements may also be observed in the legs. They cease at once when the muscular effort is relinquished. Occasionally the muscles of the trunk present inco-ordination. Thus one patient could sit steadily on a chair when his eyes were open, but if he closed them would at once fall off. The movements of the head, face, tongue, and eyes, escape the characteristic derangement.

Even with extreme inco-ordination, the power of the muscles may be unimpaired. Occasionally some group of muscles, as the flexors of the ankle, become weak for a little time and then strong again, just as may the eyeball muscles, as we shall presently see. In some cases motor power in the limbs remains unimpaired to the end; more often, when the ataxy has become great, some muscular weakness supervenes, with or without wasting of the weak muscles. There is a distinct group of cases in which weakness and ataxy come on together, but these are considered separately (" Ataxic Paraplegia ").

Sensory symptoms are prominent in most cases,-subjective sensa tions, especially of pain, and loss of sensibility. Spontaneous pains are present in some degree in nine tenths of the cases of tabes. The most frequent and characteristic are the sudden and lancinating pains called "lightning pains." They occur chiefly in the legs, but may be felt in the trunk, arms, and even in the head. They are usually paroxysmal and apt to come on at night; attacks of such pains last for some hours or for a day or two, varying in seat, but often felt in the same part throughout an attack, or through many attacks.