due to compression, to extend farthest along certain tracts, irrespective of their secondary degeneration, and in some cases this extension occurs through a considerable extent of the cord. An ascending inflammation limited to the pyramidal tracts may, for instance, be traced through several segments. The fact suggests that the neuroglial elements may share to some extent a difference that obtains between the fibres of different tracts, and it may easily lead, and probably has led, to erroneous conclusions. Softening of the spinal cord is very common. Whenever the nervefibres are broken up into disconnected globules of myelin, separated by serum in a sort of emulsion, the consistence of the part is necessarily lessened. Acute inflammation always causes such a breaking up of the nerve-fibres, and hence inflammation always causes softening as its first effect. The separate particles are augmented by leucocytes, which escape abundantly into the tissue. Ultimately, connective-tissue elements are formed, which increase the consistence, it may be up to, and even beyond, the normal degree. In a very chronic inflammation the formation of new tissue may proceed pari passu with the destructive process, and there may be at no time much diminution of consistence. It is in these cases that it is difficult to draw the line between inflammation and degeneration. Does such softening of the cord occur apart from inflammation ? The question is not easy to answer. In the brain, necrotic softening is very common as a consequence of arterial obstruction-is indeed the common form of softening. But in the spinal cord we have no evidence of the occurrence of necrotic softening. If embolism occurs, it is excessively rare. The course of the vessels does not favour the passage of a plug into them, while the vertical connection in the anterior spinal and anastomotic arteries (see p. 188) will prevent damage from obstruction in the central system unless this is situated in the terminal vessels of the grey matter. Arterial thrombosis, due to atheroma of the walls of the vessels, such as is so common in the brain, probably does not occur in the cord. The arteries are smaller than those in which atheroma is met with in the brain, and the lowness of the blood-pressure within them involves the absence of the chief cause of atheroma. It is possible that spontaneous thrombosis may sometimes set up the changes that are now regarded as those of primary inflammation; and such a lesion has actually been met with, but only in isolated form, and we have no evidence of its frequency. Besides the morbid processes to which the cord itself is liable, it suffers also in consequence of disease outside it. It may be compressed by growths springing from the membranes or bones, and by products of inflammation within the spinal canal. Compression not only causes degeneration of the nerve-elements, but usually excites actual inflammation. This "compression-myelitis " may attain a degree and an acuteness out of all proportion to the causal compression. The membranes may be the seat of hæmorrhage which com at a later date. Symptoms of such injury, in slight degree, are not uncommon. Fracture may occur at any part of the spine, but is most frequent at the fifth or sixth cervical, and at the last dorsal or first lumbar vertebræ. In the dorsal and lumbar regions, the bodies are broken in two thirds of the cases, but in the cervical region, the arches alone are fractured in one half. Usually there is a displacement of the vertebral column at the seat of fracture. Rarely the bodies may be crushed without displacement. The displacement of the bone involves a narrowing of the canal and, usually, compression of the cord. This may also result when the arches only are driven in. But the cord may be seriously damaged when there is no permanent narrowing of the canal, as in Figs. 85 and 86. The dura mater is rarely torn except There FIG. 85.-Fracture of the first lumbar vertebra. DM. Dura mater. by a splinter. Blood is almost always extravasated outside the dura mater, often in considerable quantity, from the rupture of the large veins in this situation. There are usually only small extravasations in the pia mater. The cord is, in most cases, bruised and compressed by the lower fragment (Fig. 87). Sometimes it is flattened, and it may even be divided, all nerve-substance being squeezed out of the pia-matral sheath at the spot. In the case shown in Figs. 85 and 86 the cord appeared to have been split longitudinally at the spot, perhaps by the nerve-force of the concussion. It is very common to have local myelitis, opposite the fracture, without any permanent narrowing of the canal or compression of the cord, the inflammation seems to be the direct result of the concussion. Blood may be extravasated into the bruised part, sometimes in minute spots, sometimes in larger hæmorrhages, and even into the central canal. These changes are usually limited to the spot directly damaged, but secondary myelitis may be set up, and sometimes extends beyond the contused area. It FIG. 86.-Spinal cord damaged by the fracture shown in Fig. 85. The elements of the cord itself are changed beyond the possibility of identification. The ascending degeneration is shown in Fig. 74. FIG. 87.- Fracture of the body of the fifth dorsal vertebra and of its processes. (After Gurlt.) may even extend through the whole length of the cord below the injury, and then its central functions are abolished (see p. 228). In cases of some duration the usual ascending and descending secondary degenerations are also found. It is important to note, moreover, that the secondary degenerations have sometimes the irritative character already described (p. 229, note), and that an ascending inflammation may for a short distance above the lesion be limited to a tract that degenerates downwards (see p. 232). Fig. 74, p. 177, represents sections of the cord from the case of fracture figured above. Occasionally the injury leads to secondary caries of the bone, with all its consequences. SYMPTOMS.-Three classes of symptoms result. (1) The local indications of the injury to the spine. (2) There may be certain nervous symptoms not distinctly due to the damage to the cord. One of these is general shock, which may be so great as to entail transient loss of consciousness. Vomiting occasionally occurs. There is great pain in the position of the fracture, rendered very intense by pressure, and often radiating along the nerves which come from this part, the roots of which are compressed. In rare cases epileptiform convulsions have followed fracture, usually at an interval of some days. (3) Symptoms which result from the damage to the cord, and consist in paralysis of the parts below the injury. Its character depends on the amount of damage. If this is considerable, there is both motor and sensory paralysis up to the level of the lesion, with loss of power over the sphincters. Reflex action is lost at the level of the lesion, and the examination of the trunk-reflexes often gives important VOL. I. 16 information regarding the extent of the damage, when this is in the dorsal region. Below, reflex action is commonly in excess, unless the centres are impaired by descending myelitis. Spasmodic twitchings sometimes occur in the limbs immediately after the injury, accompanied by priapism. The pains are severe in the arms when the fracture is opposite the cervical enlargement, and in the legs when at or below the lumbar enlargement, so as to damage the nerve-roots. In these cases there may be rapid wasting of the muscles, with loss of electric irritability. There is usually at first incontinence, afterwards retention of urine, but the former is persistent if the lumbar centres are damaged. Cystitis, bedsores, &c., may supervene. Ultimately, if the damage is above the lumbar enlargement and the patient lives, there may be increased myotatic irritability in the limbs, progressing to spasm, so that spastic paraplegia results. Special symptoms result when the injury is in certain parts of the spine. Fracture of the first two cervical vertebræ causes instant death, unless the displacement is very slight, and even then there is imminent danger of further displacement, with the most serious consequences, on any incautious voluntary movement. With slight displacement persons have been known to live for weeks, and then die from secondary myelitis; they have even recovered altogether. Now and then there is no compression of the cord, although there is distinct displacement, even sufficient to be recognised in the pharynx (Leyden). In such a case death has resulted at a later period from caries. The characteristic symptoms are local pain, increased by all movements (which are rendered almost impossible), displacement, and spinal symptoms. The latter may be slight merely difficulty in breathing or swallowing-or considerable, and involving the trunk and limbs. Sometimes there is hyperpyrexia. Not more than one case in fifty recovers. Middle Cervical Vertebræ.-The third, fourth, and fifth vertebræ are most frequently fractured. When the injury to the cord is considerable, death usually occurs very rapidly, because the roots of the phrenic nerve are involved, the intercostals being necessarily paralysed with the parts below. In some cases there is little immediate displacement, and the symptoms are slight until further displacement occurs in some movement. Thus a man who had met with an injury of this kind went to be shaved; during the proceeding, his head was turned on one side by the barber, with the unexpected result of causing displacement of the fracture, and immediate death. When the fracture is at the cervico-dorsal region, opposite the lower part of the cervical enlargement, the arms frequently escape at first, the early paralysis being confined to the legs and muscles of the trunk. Respiration is diaphragmatic only. After a few days the arms become involved, but their paralysis is often partial, affecting, for instance, only certain muscles, as the extensors of the hand, and it is often accompanied by local spasmodic movements. Movements and pressure cause pain, and there is local muscular rigidity. The head may be in normal or in abnormal position. Vaso-motor disturbance in the face and general hyperpyrexia have been observed. In fracture of the dorsal vertebræ (2-11) the arms escape, the legs are paralysed, and the trunk-muscles up to the height of the lesion. The pain in the trunk may be very severe. There is hyperesthesia or anæsthesia in the parts below. The reflex action in the legs is excessive; that in the trunk is abolished at the level of the lesion. The last dorsal and first lumbar vertebræ are fractured more frequently than the others, and there result paralysis of the legs, complete or irregular, severe pains, tingling, &c., sometimes followed by hyperæsthesia or loss of sensibility, and by rapid disturbance of nutrition, in both the muscles and the skin. In fracture of the lower lumbar vertebræ the symptoms are often slight; below the extremity of the cord the nerves occupy a smaller space in the canal, and so may escape compression by a moderate displacement. If they suffer, the fractured vertebræ unite very slowly. A false joint is occasionally formed. Secondary myelitis and its consequences are frequent causes of death at a variable period after the injury. CARIES OF THE SPINE. Caries of the bones of the spine is a frequent cause of paraplegia. It is often termed "Pott's disease," from the English surgeon, Percival Pott, who first described it (in 1779) as a cause of paralysis. CAUSES. Males are said to be rather more liable than females, but the difference in sexual incidence is not great. It is more common in childhood (after three), and next in early adult life, but it may occur at any age, and is perhaps more common in the second half of life than any other scrofulous lesion. I have known it commence at fifty, and it has been met with as late as seventy. It is distinctly a manifestation of the tubercular and scrofulous diathesis, and evidence of such inheritance is to be traced in most cases. Occasionally the sufferer bimself presents such indications, lung disease, &c., or caries of other bones. It occasionally develops simultaneously with other signs of acute general tuberculosis. Injuries seem frequently to excite the bone mischief in the spine, as they certainly do analogous bone disease elsewhere, in those who are predisposed; possibly, sometimes, in healthy persons. Falls, blows on the back, and severe strains are the most frequent traumatic antecedents. The last may act by straining the ligaments and setting up inflammation, which spreads to the bones directly or through the invertebral cartilages. There is usually an interval, sometimes of many months, between the injury and the definite symptoms of bone disease. LANGI DILICA LIBRARY UV RIY. EDICAL CENTER |