capacity undergoes subsequent failure, which can only be due to a process of structural change. It is possible that we have here, again, a double morbid process, and that a tendency to early degeneration in the nerve-elements is associated with a converse tendency to overgrowth of the interstitial tissue, analogous to that which we have in the muscles in Pseudo-hypertrophic Paralysis (q. v.). In this connection it is important to note that, in one case, the neuroglial overgrowth suggested a pure increase of the normal tissue, rather than a result of inflammation; and the peripheral sensory nerves, although not degenerated, contained a considerable number of embryonal nerve-fibres in the fasciculi. Déjérine would regard the neuroglial increase as the sole element in the morbid process; but the fact last mentioned, as well as the preponderant affection of certain tracts, makes it improbable that this exclusive view is correct.

DIAGNOSIS.-In most cases the inco-ordination is sufficiently predominant to suggest that the disease is a form of ataxy, and the unsteadiness of the head, the affection of articulation, the nystagmus, and the age at onset, suffice for the distinction from ordinary tabes. The common form of ataxic paraplegia bears a close resemblance to this disease, a resemblance that is more than superficial, although the excessive knee-jerk and foot-clonus, almost always present in ataxic paraplegia, are usually absent in hereditary ataxy; much spasm is always absent, and nystagmus is common. The difference in the state of myotatic irritability is, as we have seen, not absolute; cases of combined lateral and posterior sclerosis occur, of tabetic type, in which the knee-jerk is lost, and in at least one case of hereditary ataxy the knee-jerk has been excessive. The age of onset and family multiplicity may decide the question, but the isolated cases, which are by no means rare, commencing soon after puberty, are not distinguishable from the hereditary disease; they seem to be analogous to the isolated cases of pseudo-hypertrophic paralysis. A greater difficulty is presented by cases of slight tabes in children, the subjects of inherited syphilis, in whom it is not uncommon for some weakness of the legs to co-exist, or speech to be disordered, in consequence of some early lesion of the brain. The loss of the iris-reflex should suggest inherited syphilis, and other indications of this will often decide the nature of the case.

Disseminated sclerosis presents inco-ordination, nystagmus, and impaired articulation, but the ataxy of the arms differs in the wide range and violent character of the disordering jerks which characterise this disease; while simple unsteadiness of the legs is very rare, and the course of the malady is more rapid. The affection of speech differs from that of hereditary ataxy in being simply " staccato," with undue separation of syllables, which are rarely run together. The cases are always isolated.

Cerebellar tumour and hereditary ataxy can hardly be confounded,

Auscher, 'La Semaine Méd.,' 1890, No. 32.

in spite of the fact that the unsteadiness in walking is very similar in the two diseases; the common affection of the arms in the one, and the conspicuous head symptoms (severe pain, optic neuritis, &c.) of the other, sufficiently distinguish them. It is very common for the tremor of the head to be at first ascribed to mere 66 nervousness," and also for the isolated form, in girls, to be regarded as hysterical. The presence of nystagmus should at once decide the question; it is absolute proof of definite disease.

PROGNOSIS. The prognosis in every case is very serious, since the disease, being a developmental affection, is essentially progressive; but life may be prolonged for many years, and in slight cases the malady may interfere comparatively little with the patient's occupation. Thus I have known a man, with very marked symptoms, follow his business as a tradesman for many years. The only guide to individual prognosis is the observed rate of progress, which has little relation to the age at which the symptoms commence.

TREATMENT.-As in other diseases that depend on a congenital tendency, treatment is almost powerless. The measures recommended for ordinary locomotor ataxy (apart from those suggested by the special symptoms of tabes) are those most suitable to the hereditary form. Arsenic, phosphorus, and nitrate of silver deserve a trial; now and then they seem to check the progress of the disease for a longer or shorter time, but its individual tendency determines its course, almost irrespective of treatment.

SIMPLE SENILE PARAPLEGIA.

This name seems the most unobjectionable for a condition, somewhat rare, which appears hitherto to have been unrecognised. It is confined to late life, occurring in those over 40, and especially over 50. Its characteristic is simple weakness of the legs, with some slowness of movement, but without wasting, sensory disturbance, or reflex alteration. The knee-jerk is normal, and there is no foot-clonus. The malady develops very gradually and is slowly progressive, although it seems seldom to attain such a degree as to prevent standing. The condition of the legs resembles that in cases of paralysis agitans without tremor, in which the malady is manifested only by weakness, and stiff slowness of movement of the limbs, face, and trunk. Cases are met with in which the condition of the legs above described is associated with slight symptoms in the arms and face, such as characterise these cases of paralysis agitans. This senile paraplegia is probably a partial development of the morbid process of that disease; instead of being general, it is limited to the structures for the legs. If, as the condition seems to suggest, paralysis agitans depends on peculiar changes in the A uote upon it by myself appeared in the Centralbl. f. Nervenkr.,' 1890.

nutrition and function of the motor cells of the cortex cerebri (which impair the power and alter the action of the cells, but do not usually go on to such destructive alteration as entails secondary degeneration of the pyramidal fibres), we can readily conceive that such a process. may be sometimes limited to the leg-centres, and may cause the symptoms. If so, the malady is a cerebral and not a spinal one, but it is mentioned here on account of its paraplegic features, and their resemblance to those of disease of the spinal cord. Degenerative changes may, however, be various in kind and degree, especially in late life; cases occur, similar to these, but with myotatic excess connecting them with the destructive changes of lateral sclerosis, while others present such symptoms as nystagmus or impeded articulationevidence that the altered nutrition is wider in its range.

CHRONIC SPINAL MUSCULAR ATROPHY

(PROGRESSIVE MUSCULAR ATROPHY; WASTING PALSY; AMYOTROPHIC LATERAL SCLEROSIS; CHRONIC POLIO-MYELITIS).

The disease which has long been known by the names "progressive muscular atrophy" and "wasting palsy" is characterised by slow wasting of the muscles, beginning in some one part, and usually spreading and increasing until it is wide in extent and extreme in degree. The changes in the muscles depend on changes in the spinal cord, a slow degeneration of the ganglion-cells of the anterior cornua, accompanied by a similar degeneration in the motor nerve-fibres which spring from the cells. With this degeneration of the cells and peripheral fibres there is usually also associated a degeneration of the pyramidal tracts in the cord, sometimes, at least, to be traced up to the motor cortex of the brain.

Chronic muscular atrophy was separated from primary paralysis by Sir Charles Bell, and was afterwards described more fully by Aran and Cruveilhier. Bell and Cruveilhier regarded it as a spinal disease. Aran (who first called it "progressive muscular atrophy ") thought that it was primarily a disease of the muscles, a view that was afterwards held by Duchenne, and subsequently also by Friedreich. This opinion was supplemented by a theory that the wasting was due to a disturbance of the sympathetic. Lockhart Clarke first discovered the disease of the grey substance of the spinal cord, and Charcot specially associated the atrophy with the wasting of the ganglion-cells. When the constancy of the spinal lesion was demonstrated, it was thought that every form of chronic muscular atrophy was of spinal origin; but this view has proved erroneous, and it has been shown that there are forms of muscular atrophy which are purely local and idiopathic. The morbid process is not confined to the spinal cord. Atrophy of the nerve cells from which the motor bulbar nerves arise often accompanies

that of the spinal cells, and "progressive bulbar paralysis" is then associated with "progressive muscular atrophy:" it often comes on after the disease has existed for some time, and ends life; occasionally it initiates the malady.

Two varieties of the disease have been distinguished by Charcot, who has been followed in this by most subsequent writers. In the one variety the disease is manifested only by the wasting of the muscles; in the other there are, in parts other than those much atrophied, the indications of degeneration of the pyramidal tracts of the cord. In the latter cases, Charcot regarded the degeneration of the pyramidal tracts as the primary lesion, and the affection of the cornua as secondary. He therefore termed the cases of the first class "protopathic," and those of the second class "deuteropathic," and gave to the latter the name "amyotrophic lateral sclerosis." In Germany, however, and especially by Leyden, doubts have been expressed as to the validity of the distinction between the two classes of cases, and as to the sequence of the lesions in the second class. These doubts are not without foundation. The subject will be discussed when the pathology of the disease is considered, and reasons will then be given for the course here adopted of considering the two varieties together as essentially one disease.

But cases are also met with (although not frequently) that present every gradation to subacute polio-myelitis in one direction, and perhaps also to polyneuritis in another. Attempts are being made to classify these, but types may be multiplied indefinitely from the intermediate forms, and many more pathological and clinical observations are necessary before a useful classification of the cases can be made. In the following description the common forms are chiefly considered.

CAUSES. The disease is more frequent in males than in females, the proportion being about three to one. It is chiefly a disease of adult life, commencing usually between twenty-five and forty-five. I have known it to begin at fourteen and as late as seventy, and a case is recorded in which it began at twelve; there was wasting and rigidity in the limbs, tongue, lips, and lower face. But most cases of muscular atrophy in early life are idiopathic, and not spinal. Heredity is to be traced only in less than half the cases, and generally as an indirect neuropathic disposition. Rarely there is direct inheritance of the disease. Among instances that I have met with are a lady whose mother died from a similar atrophy, and another case (from which Fig. 135 is taken) in which a brother had died from some chronic disease of the cord, attended with wasting; but three cases with bulbar symptoms have been recorded, two of whom were cousins, the children of two sisters: the third, who had had syphilis, was a cousin, but his affection was untypical Direct inheritance seems to be most common in cases that occur late in life. When many members of a family suffer from

• H. Blumenthal, “Inaug. Diss.,” “Neur. Cent.,' 1884, p. 376.
† Virchow's Archiv,' 1889, p. 115.

muscular atrophy, the malady is nearly always idiopathic and not spinal. The affection occurs in all classes of society, and it is doubtful whether workers with the muscles furnish a larger proportion of the cases than can be accounted for by their greater exposure to certain exciting causes.

Of these more direct causes one of the most frequent is mental distress and anxiety, and this is especially met with in females and in late life. A severe fright has been thought to excite it. Another cause is exposure to wet cold, which is also a cause of many other chronic spinal diseases. Sometimes the exposure has been habitual; sometimes a single exposure has been effective, and some neuralgic pains, indicative of the deleterious influence on the nervous system, have followed the exposure and connected it with the later wasting. The pain has been either in the part afterwards wasted, or in some other, more common, seat of neuralgia. Thus one patient, after remaining in wet clothes for twelve hours, suffered for six weeks from severe neuralgia in the left side of the face, and then the muscles of the left shoulder began to waste. Although excessive use of individual muscles may cause them to waste, it is doubtful whether this influence produces general muscular atrophy. Injury to the cord, such as results from concussion of the spine, is a rare cause. It more often produces disseminated myelitis, which may be manifested by muscular wasting combined with other symptoms.* In a few instances I have known progressive atrophy, of typical characters, to slowly follow a concussion, as if this had set up a perversion of the nutrition of the nerve-elements. Still more rarely a fall, injuring one limb, has been followed by muscular atrophy commencing in this limb and becoming general. Thus a woman fell downstairs, and pitched on her left hand and wrist; she had pain in the arm for a long time; two years after the fall this arm began to waste, and the atrophy ultimately became general. The relation might be passed as an accidental coincidence, were it not that in other central diseases-even, for instance, in paralysis agitans-the symptoms may commence in an injured limb. In rare cases, the disease develops, during adult life, in a subject of old infantile palsy (polio-myelitis), and may start from the most affected part (see p. 364).

The disease sometimes succeeds syphilis, and no other cause may be traceable. As with other degenerative diseases, an interval of years elapses between the primary disease and its nervous sequel. The cases that I have seen after syphilis have been typical in course, and evidently degenerative in nature. That syphilis has some share in the causation of these cases is probable from its relation to other diseases, such as tabes; but it is noteworthy that in one case the wasting commenced during, and in another directly after, an energetic

In one unusual case the wasting (ultimately general) began in the deltoids a month after a fall, which probably fractured the base of the skull (Manor, 'Alienist and Neurologist,' 1886, p. 430).