(unless the disease involves the lumbar enlargement), and great excess of the superficial reflex action is a common and important feature. The legs are often cold, and sometimes perspire continually. The sphincters are often affected, sometimes early, but they may escape even where there is complete motor palsy of the legs.

Complications.-Among common complications are bedsores, cystitis, various secondary effects of the bone disease, such as abscess, local scrofulous disease elsewhere, and general tuberculosis. Tubercular tumours in the brain occasionally coincide with the caries. In very severe cases peculiar secondary mischief has occurred in the spinal cord, and has run an independent course, giving rise to very anomalous symptoms. Thus a descending myelitis may invade the lumbar enlargement in its entirety and abolish its central and reflex functions, causing rapid wasting of the muscles and acute trophic changes in the skin. Inflammation may ascend the pyramidal tracts and thus paralyse the arms-an instance of the strange limitation of inflammation to functional tracts when it passes in a direction opposite to secondary degeneration. Ascending degeneration of the posterior median columns may spread to the postero-external columns, and cause symptoms of ataxy by invading root-fibres at a higher level. Ataxy may come on as the power returns, when the disease is in the dorsal region, probably by damage to the path from the muscles to the cerebellum. Lastly, myelitis may occur in disseminated foci in various parts of the cord, and even in the medulla, giving rise to scattered symptoms of anomalous character.

Course. The bone disease may heal, union occurring between the altered tissue, or it may persist with continued formation of pus, or may become quiescent with occasional periods of renewed activity. The cord mischief is influenced by the state of the bone disease, although its progress may be to some extent independent. Thus inflammation in the cord, in excess of the compression, may subside in spite of the continuance of the bone mischief. Pressure on the cord may be relieved, although the bone disease continues, and even sometimes as a result of the increased breaking down of bone and exit of pus by another channel. A case is mentioned below in which paraplegia passed away as angular curvature developed. Hence, there is no strict correspondence between the course of the bone mischief and that of the cord disease. In some cases the paralysis, motor and sensory, persists. More often the sensory loss passes away, while motor paralysis remains, usually as spastic paraplegia, and, in severe cases, flexor spasm comes on with muscular contractions. Life may

be prolonged in that condition for years, but often, in such cases, bedsores form, or cystitis leads to kidney disease, or other tubercular disease develops and leads to death, or the lessened respiratory power renders an attack of bronchitis fatal. In many cases, again, the paralysis gradually passes away even when the compression continues, and See Charcot, 'Leçons sur les Mal. du Syst. Nerv.,' tom. ii.

the cord is found considerably narrowed if the patient dies from some other cause. It is possible that such compression is sometimes produced slowly without impairment of conduction. In children recovery occurs far more readily than in adults. Even in adults, however, recovery may occur from palsy that has lasted for more than a year, with all the signs of descending degeneration in the cord, amounting to severe spastic paraplegia. Usually rest on the back or mechanical supports are necessary to secure recovery, but it occasionally occurs without these measures. A youth acquired angular curvature at sixteen; at twenty paraplegia came on slowly, and progressed, with some variations, during the next seven years. There was then absolute motor palsy in the legs, and sensation was lessened. He refused to rest, and continued to follow his occupation, which was however a restful one, that of a tailor; he took cod-liver oil and iron, and gradually regained useful power, so as to be able to walk about. Such a case, however, is exceptional.

As

Relapses sometimes occur in cases that improve, although they are certainly not nearly so frequent as might be expected from the nature of the disease. In the majority of cases recovery, once obtained, is permanent. In a minority the paralysis returns when some exciting cause renews activity in the bone disease. The tendency to relapse and possibility of repeated recovery are very strikingly shown by the following case. In a girl of fifteen, paraplegia developed during nine months, slowly at first, more rapidly towards the end of that time. She came under my care six months later, having been unable even to move her legs for that time. Bone disease had not been previously suspected, but there was slight tenderness and enough lateral irregularity of the lower dorsal spines to show the nature of the case. Rest in bed and tonics were soon followed by improvement; in six weeks she could stand, and in four months was able to walk well. she gained power, angular curvature came on, prominence of the seventh and eighth dorsal spines. Five months after her discharge, she fell and struck her back; the curvature increased, and her legs gradually became weak again. Seven months after the fall she was readmitted, unable to stand, although the paralysis was not absolute. There was foot-clonus on each side. Sensibility was lessened below the ensiform cartilage. Rest on the back was again followed by slow improvement. In three months she could just walk. She was then suspended, and encased in plaster of Paris. At the end of another month she could walk about the room, and no clonus could be obtained. She was soon afterwards discharged, and her progress continued, so that, at the end of nine months, she could walk five miles, and there was no trace of clonus, although there was still some excess of the knee-jerk. She soon afterwards married, and bore a child, which died two years and a half after her discharge. She caught cold at the funeral, and a fortnight later again began to lose power; in six weeks the legs were almost motionless, with marked

foot-clonus; sensation to touch was lost up to the umbilicus, that of pain being preserved. Neither rest nor encasement caused any improvement. After some months sulphide of calcium was given, and in a few days power began to return; in a month she could take a few steps, and in four months she could walk about the ward without difficulty. She made another good recovery. Some years later, however, paralysis again came on, and this attack proved permanent.

Several cases have come under my notice in which the subjects of caries in early life, which healed without damaging the cord, have at some period in adult life presented the symptoms of primary lateral sclerosis-simple spastic paraplegia, without any root symptoms or evidence of renewed activity of the bone disease. If there is a connection between the two, it is probable that the cord has suffered compression so slowly that its functions have not been interfered with, but, nevertheless, the vitality of the pyramidal fibres has been rendered less enduring

It is important to remember that the deviation is often lateral,* and the chief difficulty is due to the fact that a slight lateral deviation or slight prominence is not unusual in normal spines. Hence it is important for the student to make himself familiar with the degrees of deviation that occur in health. At the same time it must not be forgotten that a deviation not greater than occurs in health may be due to disease. If it coincides with distinct tenderness, and especially also with the position of root symptoms, it may be accepted as evidence of disease, probable or certain, according to the character of the symptoms.

The pathology of the affection only concerns us so far as it relates to the effect on the spinal cord, and this is considered in the chapter on Compression.

DIAGNOSIS.-When clear indications of caries precede the paralysis, the nature of the case can hardly be mistaken. The obvious inference, that the affection of the cord is secondary to that of the bone, is scarcely ever wrong. When the two develop together, mistakes in diagnosis are often made, but are usually due to the want of repeated examinations of the spinal column. It is when the root or cord symptoms precede distinct evidence of bone disease, and when the latter is so slight as to be equivocal, that the chief real difficulty in diagnosis occurs; the affection is apt to be mistaken for a primary disease of the cord or its membranes-a transverse myelitis when the dorsal region is affected, a progressive muscular atrophy, or primary pachymeningitis, when the disease is in the cervical region. A correct diagnosis can only be made in these cases by recognising the significance of the slight bone symptoms that are always present, the deep tender. ness, and often slight irregularity. Even slight irregularity derives

To discover lateral deviation it is well to make an ink-dot on the skin over the middle of the tip of each spine, care being taken that the skin is not stretched to one side. The ink-dots may be copied on tracing-paper.

significance from tenderness, limited in extent and corresponding in position to the deviation. The irregularity may be absent at first, and then its development is doubly significant. An observed increase in the amount of displacement gives significance to even a slight irregularity.

The early excess of the cutaneous reflex action (from the sole, for instance), while not conclusive, adds weight to the other symptoms of bone disease. It may be very marked even while the patient is able to walk about. Distinct root pains are always of great significance, and this is increased by the detection of spots of anesthesia along their course. All these symptoms derive additional weight from their coincidence in level with the spinal irregularity.

It is this which enables the pains to be distinguished from the condition for which they are most frequently mistaken-a trunk neuralgia. This error is especially common when the pain is chiefly unilateral. In all such cases the spine should be carefully examined, and any tenderness of the bone at the level of the pain should excite suspicion. I have also known unilateral abdominal pain due to caries to be mistaken for that of renal calculus.

When damage to the cervical roots causes muscular wasting in the arms, the case may be mistaken for one of progressive muscular atrophy, but differs in the distribution of the wasting, in the pains, and the impairment of sensation. These occur in primary cervical pachymeningitis, which is distinguished by the absence of the signs of bone disease, and in the wider extent through which the root symptoms extend.

In the first half of life the recognition of bone disease is practically tantamount to the recognition of caries. In the second half, however, the relative infrequency of caries, the greater frequency of growths in the bone, and the occurrence of eroding aneurisms, introduce a fresh diagnostic problem. The absence of any other indication of a tumour or an aneurism is the first distinction; and the second is the fact that in both these diseases the root pains commonly reach a degree of severity scarcely ever attained in caries, and are especially increased by movement.

When there are merely tenderness of the spine and slight weakness of the legs, the question may arise whether there is organic disease, or merely the condition termed "spinal irritation," or mere functional pain and tenderness and weakness of the legs. In these cases the tenderness is usually found over a considerable area of the spinal column, with more than one point of special intensity; it is superficial as well as deep, and may change its seat; there are no root pains or spots of anesthesia. There is more danger that caries of the spine in a young woman may be passed as hysterical paraplegia than of the opposite error. Especially when the subjects of caries present distinct symptoms of hysteria, there is risk, as experience shows, that unequivocal symptoms of caries may be overlooked. Some other

diagnostic indications are mentioned in the chapter on Slow Compression.

PROGNOSIS. Our ignorance of the precise character of the morbid process which is damaging the cord renders the prognosis, in every case of caries, a matter of much uncertainty. Nevertheless there is no disease of the cord in which symptoms of equal gravity so often pass away. The cases are few, therefore, in which hope is unjustified, but they are equally few in which we are warranted in a confident expectation of recovery. In childhood the prospects of recovery are certainly better than in adult life, and they are least in declining years. Damage to the cord between the enlargements is less serious than when these are affected, because the strong tendency to trophic changes constitutes a grave danger when the lumbar enlargement is diseased, and the diminished breathing power an equally serious danger in disease of the cervical enlargement, especially when this is high enough to entail the additional danger of paralysis of the diaphragm.

But how perilous a condition may be recovered from is shown by the fact that the child mentioned on p. 247 had paralysis of all four limbs, the diaphragm, and weakening of the intercostals, and yet recovered. Still more striking is a case narrated by Dr. Buzzard, in which disease in the region of the third cervical vertebra caused almost complete palsy of arms, legs, intercostals, and diaphragm, respiration being carried on by the accessory muscles of the neck. Yet the child recovered in spite of the occurrence of an attack of pneumonia when the paralysis was at its height. A girl of thirteen, whose cervical caries was accompanied by all the symptoms of cerebellar tubercle, recovered. All these, it will be noted, were children. Neither rapidity nor slowness of onset affords any guide to prognosis, nor does the relative order of paralysis and curvature, or the degree of palsy. Severe spastic paraplegia may pass away entirely, provided it remains extensor in character. The prognosis is perhaps a little better when there is no loss of sensation, since this proves that the damage to the cord is moderate in degree; but even complete anæsthesia does not preclude recovery, as the cases mentioned show. The danger to life is dependent in considerable degree on the evidence that the scrofulous or tubercular tendency is active elsewhere, and also on any difficulty in securing proper treatment. The prognosis is, moreover, at present in a transitional state on account of the uncertainty regarding the range of successful surgical treatment.

TREATMENT.-The first and chief element in the treatment of paralysis is that of the bone disease which causes it, and for full details of this the reader is referred to treatises on Surgery. It includes both the older means of securing an arrest of the morbid process, and, secondly, the still recent measures of operative treatment. If the bone disease heals, the spinal cord, in most cases, will The two most potent therapeutic agents are persistent

recover.