392 PATHOLOGY women, but it disappears with delivery. The movements are intermittent, beginning from a state of repose with a certain fidgety restlessness, and going on to the most irrelevant and un rhythmical jerkings, hitchings, and twistings of the limbs, head, and body, or of one limb only, or one shoulder, or of the head only, or of the tongue. The muscles do not cease to be the ministers of the will, but voluntary movements are performed with some want of aim and certainty ; and the gait in walking may be seriously affected. The choreic movements themselves can not be restrained by the will ; excitement and self-consciousness intensify them ; and they cease during sleep. One of the most singular facts in this strange nervous habit is its association with rheumatic fever ; a significant proportion of those subject to it are found to have had rheumatic fever, but there are others, curiously enough, who afford indications only of that state of the endo cardium (or lining membrane of the heart and its valves) which often goes with rheumatic fever. This fact of endocarditis has suggested a theory that the disease is due to the minute arteries of the corpus striatum being blocked with small fibrinous plugs washed off from the inflamed interior of the left ventricle, or from the surface of its valves. It is more accordant, however, with all the phenomena to regard the disease as a functional habit of muscle and nerve, with the usual intermissions of a nervous habit and the usual exacerbations, in which the implication of the heart-muscle creates a peculiar liability to endocarditis. A further analysis is offered at the end of the remarks on rheumatic fever (p. 398). Mimetic Mimetic and Epidemic Chorea. The choreic habit has, like and epi- hysteria, a singular power of becoming a fixed idea in others ; there demic is no doubt that choreic movements are involuntarily mimicked by chorea, young persons who witness them in orphanages or other institutions Avhere a number of girls are living under the same circumstances of work and leisure. Chorea may thus be said to be contagious, while epilepsy is hereditary. It is no great step from these cases, which depend solely upon the fantastic trick being caught under the influence of the idee fixe, to the remarkable epidemics of dancing frenzy of which some are historical, and of which there are still instances occurring from time to time under some general excite ment, particularly the vivid prepossession of a large number of persons at once by the same religious hopes and fears. In this connexion come certain other diseases ecstasy, catalepsy, and hysteria, -of which the details are given in the respective articles, ECSTASY, &c. Degenera- Diseases of the Spinal Cord. In the foregoing group of errors of tiou.s the nervous control we have had to consider a mere functional con- of spinal dition, a molecular state, no doubt, but one which cannot be seen cord. any more than can the electricity in a wire. Structural changes, when they occur at all, are a very late effect, as in some cases of epilepsy. But there is a very large and important part of the functional errors in the controlling nervous mechanisms which are associated with textural changes or degenerations. The most obvious of these are disorders of the reflex functions of the spinal cord. In respect of these structural changes accompanying func tional irregularities, the spinal cord approximates to the organs and parts of the body which we have already considered. But there is one character in the textural changes of the spinal cord (and of the brain) which is in a sense unique, namely, their tend ency to spread up and down in the particular tracts of fibres. Hence the ascending and descending degeneration and sclerosis of the cord, the extensions of bulbar paralysis, and the like. Loco- Locomotor Ataxia, or Tabes Dorsalis. The muscles of the body act motor ordinarily in groups, so that complex movements, such as carrying ataxia. a spoonful of soup to the mouth, are performed by a number of independent voluntary muscles as if by a mechanism or automaton. The highest point attained by the muscles in this direction is the precision of military drill. In the disease called locomotor ataxia the muscles that are ordinarily grouped together in their action become slow to act in concert, the want of co-ordination being most obvious in the legs and hips in walking. Progression is not of the usual well-considered kind, but the leg is thrown outwards as well as forwards, and the foot is brought down as if the inten tion were to strike the ground with it, the knee having been pre viously straightened. With so little case are these muscular com binations initiated that the patient requires to look at his feet as if the sense of effect were failing and had to be aided by the sight. Later on the muscles of the upper extremity are in like manner unable to act consentaneously, so that the patient cannot fasten a button, pick up a pin, or the like. Still later there is not only loss of the nicely-adjusted harmonious action among the muscles, but there is a loss of all moderation or graduation in the move ments instituted. Whether or not this also be due to loss of the sense of effect, the movement is not adapted to the effect required ; it is quick and of short range even when it should be slow and sweeping, and the time and range of the movement of the given limb are practically the same under all circumstances. These errors of the locomotor control are so conspicuous as to have given the disease one of its names ; to them we have to add other symptoms varying in the different cases, such as flying pains in the limbs, numbness, squinting and double vision, and functional disorders of the abdominal and pelvic organs. A certain painless structural alteration of the joints (especially the knee), first described by Charcot, is now and then met with, and the remarkable condition known as perforating ulcer of the foot is sometimes found (but not every case of it) to be associated with locomotor ataxia. The structural changes in the spinal cord begin in the lumbar region and spread upwards ; they are in the posterior columns, and especially on their outer limits. Grey degeneration is the name given to the structural condition, and it depends essentially upon the loss of the opaque white substance that invests the axis- cylinder of each nerve like an insulating stratum ; this layer gives the colour to the white tracts of the cord, and the loss of it reduces these tracts to the grey condition of the central columns of cord where the nerves are normally without the white insulat ing layer. The degenerations of the spinal cord, however caused, have little variety ; the loss of the white substance may be followed by hardening of the tract of tissue (sclerosis), or there may be a development of the cells of the supporting tissue or neuroglia, keeping pace with the decay of the nerves themselves, whereby the tract acquires a gelatinous appearance. Sometimes the degen eration is not perfectly continuous, but occurs at many isolated spots (multiple disseminated sclerosis). The causes of the degeneration in locomotor ataxia are various. Cause: According to the statistics of Erb, it is nearly always associated of the with constitutional syphilis ; other causes are probably always degem ] peripheral somewhere within the region supplied with nerves from tions. the lumbar part of the cord. The causes of degeneration other than that of tabes dorsalis are also various, and associated with various groups of symptoms, which need not further be considered. Mechanical injury to the cord is followed by degeneration, and the pressure of a tumour may have the same effect. It is found that the solution of continuity of a nerve causes the same loss of the white substance in its peripheral portion as in these degenerations of the cord, and the degeneration of the nerve is set down to its being cut off from its <; trophic centre." The same "trophic" hypothesis is applied to the spinal decay. If the structural degeneration in the cord differs from the degenerations that elsewhere go with disordered function, in its remarkable tendency to spread up or down, that is a difference which may be itself associated with the distinctive conducting function of the nerves and nerve-centres. In so-called bulbar paralysis, associated with inarticulateness ofBulba I speech, there is described a certain decay of the ganglion-cells in paralj the nucleus of the hypoglossal nerve, situated in the " bulb " or medulla oblongata, together with general shrinkage of the nucleus ; this condition progresses both structurally and functionally towards a more general paralysis. In infantile paralysis the structural degeneration is found per- In fall vading the anterior horns of grey matter of the cord (anterior polio- paralj j myelitis), and it includes the ganglion-cells. Pscudo-hypcrtrophic Paralysis, Progressive Muscular Atrophy. Pseud : These are two closely allied conditions, the one in young children and hyper the other mostly in male adults, which afford the most instructive trophi contrasts. There is gradual loss of muscular power in both, in the paralj case of the children s malady chiefly in the coarse or static muscles sis, pr ; that keep the body erect, and in the nimble and richly inner- gressi- vated muscles of the hand, forearm, and tongue in the progressive muscu muscular atrophy of male adults. In both the loss of muscular atropl power goes hand in hand with a loss of muscular structure ; but in the coarse and sluggish groups of muscles which are mostly affected in growing children the loss of muscular structure is more than made up for, in mere bulk, by the development of interstitial con nective tissue and fat, while in the nimble muscles of the hand and tongue, chiefly and primarily implicated in the characteristic disease of maturity, there is visible shrinkage of the part. It is only in the limbs, when the affection extends to them, that the bulk and outline are preserved in adults. Hence the affection in children is called pseudo-hypertrophic paralysis, and in adults progressive muscular atrophy. A few cases of great interest have been recorded in which adults have had the two conditions in combination. Children so affected walk as if on tiptoe, with a waddling gait, balancing the body for a perceptible interval on one foot ; when they are stripped the dorsal contour is peculiar, the shoulders being thrown back and the belly forward, the calves and hips standing out prominent and hard. In the muscular atrophy of adults the ball of the right thumb is nearly always wasted, and if the other muscles of the hand are equally attenuated there is pro duced the characteristic appearance of a bird s claw ; the tongue also is often shrivelled. In contrast to locomotor ataxia, and to paralysis from injury to or pressure on the brain and spinal cord, these two diseases arc illustrations of the peripheral relationship of muscle and nerve, of a loss of integrity in that executive relationship, which brings with it both loss of power in the muscle and concomitant failure of its nutrition. They may be quoted as instances of tropho-neuroses,
