early and most active stage. It must be remembered that in all inflammations of the sheath and interstitial tissues this proceeds to a considerable degree before the fibres of the nerve suffer, and thus sudden loss of sensibility does not show that the nerve was previously healthy. This occasionally sudden onset is of much practical importance; one case was sent to me from a place in which the disease is endemic, by a doctor well acquainted with it, who had not suspected leprosy because the anesthesia came on almost suddenly.

Accompanying anesthesia there is usually some muscular wasting, which may be great. In the case figured it was considerable, although only in the small muscles of the hands was it comparable to that of progressive muscular atrophy. The electrical excitability of the mus cles was greatly lowered to each current, and this is perhaps the most common condition; either the damage to the nerves is so chronic that the fibres undergo slow changes pari passu with those in the nerves and their endings, or the patient comes under observation at a late stage in the local affection, at which the changes present in the early stage have disappeared; sometimes, indeed, all irritability has vanished. In cases that are seen soon after the onset of the lesion of the nerves, there may be the reaction of degeneration in the muscles, either partial or complete, and there is often a conspicuous exaltation of the mechanical irritability of the nerve-trunks. When the facial nerves are affected this may be well seen, and may resemble that met with in tetany.* The thickening of the nerve may be felt when that which is affected is accessible. The state of myotatic irritability varies according to the distribution of the neuritis; it is lost at places where the sensory or motor fibres are involved, but those supplying the front of the thigh and its muscles often escape, and the knee-jerk is preserved. Anchylosis of the joints may occur, as in other forms of neuritis.

The "mutilations" of leprosy, by which the ends of the fingers and toes are lost, are also regarded by some as a consequence of the neuritis. The numerous other symptoms of the disease are independent of the nerves (except perhaps the pigmentation of the skin), and are beyond the province of this book.

The neuritis of leprosy is typically adventitial (Fig. 62). The primary sheath and the secondary sheaths of the fasciculi are greatly increased in thickness, and consist of nucleated fibrous tissue arranged concentrically (A, B). From the sheath, tracts extend into the inte rior of each fasciculus (B), isolating the groups of nerve-fibres. The increase of tissue even extends between the fibres themselves (c), and these undergo slow wasting; many of the fibres in the figure are seen to be distinctly narrower than normal. The concentric growth of fibrous tissue may even invade the whole area of the fasciculus, all the nerve-fibres perishing before it (D). The characteristic bacillus of leprosy is found abundantly, in recent cases, in the new tissue of the Peculiar cells are met with, infiltrated with the organisms.

nerves.

As the fibrous tissue develops and contracts, the bacilli seem to perish, and ultimately can no longer be discovered.

The diagnosis depends on the occurrence of irregular areas of anæsthesia, generally associated with irregular patches of pigmentation and pallor in the skin, and often with muscular atrophy, in a person who has been exposed to the risk of infection, generally by having lived in a district in which the disease is endemic. The irregularity of distribution and the limitation of considerable sensory changes sufficiently distinguish it from other forms of neuritis. The spinal affections with which the mixed anæsthesia and wasting are most likely to be confounded are, as Schultze has pointed out, cases of syringo-myelia in which the distension of the central cavity damages the grey matter, and may cause similar symptoms of irregular distribution. But these are limited to the arms; and if the legs suffer it is in a different way-as simple paraplegia with excess of myotatic irritability that may go on to spasm.

FIG. 62.-Sections of nerves from a case of anæsthetic leprosy, under the care of Dr. Buzzard. A, median nerve at wrist x 5; B, portion of same more highly magnified; c, part of a less diseased fasciculus from the ulnar nerve; D, a small fasciculus from median in which the concentric fibres have invaded the whole area of the fasciculus.

The prognosis of the disease in the simple anesthetic form is grave only when the sufferer is still exposed to fresh infection, or in cases of considerable severity. But it must be remembered that, just as the disease may develop long after exposure to its cause, so it may slowly increase for a long time after this exposure has ceased.

The treatment of the affection is beyond the scope of this work; in so far as the nerve symptoms require special measures, these are the same as in ordinary neuritis. A trial may be made of the stimulation of the muscles by whatever form of electricity they will respond to, and of the anesthetic areas in the skin by the wire brush and faradism.

11

VOL. I.

PART III.

DISEASES OF THE SPINAL CORD.

INTRODUCTION.

ANATOMY OF THE SPINAL CORD.*

THE spinal cord, it will be remembered, is much shorter than the spinal canal, reaching only to the second lumbar vertebra. Hence the nerve-roots descend to their foramina of exit. The lower they arise, the longer is their intra-spinal course. All those below the second lumbar pair leave the canal below the lowest portion of the cord. It is customary to speak of the portion of the spinal cord from which each pair of nerves arise as the corresponding "segment" of the cord. The segments are longest in the dorsal region, and shortest in the lumbar enlargement. They are also called "metameres."

The only parts of the spinal column that we can usually feel are the vertebral spines. Many of these are not on a level with the bodies of their vertebræ. It is important, therefore, to know the relation of the spines to the bodies of the several vertebræ, and of these to the origin of the nerves. These relations are shown in the accompanying figure (Fig. 63).

Of the Membranes, the pia mater closely invests the surface, and is continuous with the tracts of connective tissue that pass within the substance of the spinal cord. It is also prolonged along the nerveroots as their sheaths. The arachnoid forms a much less close investment. The dura mater is not in contact with the bones, as it is in the cranium, but a layer of fat and a plexus of large veins intervene

The following outline of the anatomy of the spinal cord is intended merely to place before the reader those points that are essential, or likely to become so, for understanding the functions of the organ and the symptoms of its disease. It does not profess to be exhaustive even in outline, and is designedly kept as free as possible from whatever, in either the substance or terminology of recent science, does not come within the scope of those objects. Many of the results reached by modern investigators are mutually incompatible, and where a choice has been necessary the observers have been followed who possess the greatest authority and whose conclusions best agree with facts previously ascertained.

163

between the two. It thus forms a loose sheath for the cord, and variations in the amount of blood in the plexuses outside it permit corresponding (but inverse) variations of the amount of cerebro-spina fluid within it. An extension of the dura mater passes along each nerve-root and blends with its sheath.

STRUCTURE OF THE SPINAL CORD.The general form of the cord, the enlargements it presents, and its constitution of white and grey substance, are too well The known to need description here. white substance surrounds the grey, except at the two points at which the posterior horns come to the surface (Fig. 64). It consists of medullated nerve-fibres, chiefly longitudinal. The posterior cornua isolate the posterior columns from the rest of the white substance. These columns are separated by a "posterior median septum" of connective tissue, and a little distance from this another incomplete septum, "posterior intermediate septum," corresponding to a depression on the surface, marks off a portion next the median septum, the "postero-median column," or "column of Goll," from the part next the posterior horn, "postero-external column,"

FIG. 63.-Diagram (framed from an original investigation) showing the relation of the vertebral spines to their bodies and to the origin of the several nerve-roots. It will be seen that the ends of the vertebral spines are opposite the middle of their own bodies only in the lumbar region; they correspond to the lower edge of their own bodies in the cervical and the last two dorsal vertebræ, and to the upper part of the body below in the rest of the dorsal region. Each cervical spine is rearly opposite the lower roots of the nerve below; the vertebra prominens, is opposite the first dorsal roots, and from the 3rd to the 10th dorsal the spines correspond to the second root below; the 11th spine corresponds to the 1st and 2nd lumbar nerves, the 12th to the 3rd, 4th and 5th; the 1st lumbar to the 1st, 2nd and 3rd sacral nerves, while the top of the cord is opposite the upper part of the 2nd lumbar.

S

4

2

C 1

3

3

5

6

6

8

7

DIV.7.

8

2.

Co.

2

234

3

L

2

3

4

5.

or "column of Burdach," the part of which next the cornu is called the "posterior root-zone," because many fibres of the

posterior root pass through it. The rest of the white substance is divided, in the middle line in front, by the anterior median fissure,

FIG. 64.-Diagram of a section of the spinal cord in the cervical region. A. C., anterior commissure; P. C., posterior commissure; I. g. s., intermediate grey substance; P. cor., posterior cornu; c. c. p., caput cornu posterioris; L. L. L., lateral limiting layer; A.-L. A. T., antero-lateral ascending tract, which extends along the periphery of the cord.

down which the pia mater and blood-vessels pass, and at the bottom of which is the anterior or white commissure. Between the anterior median fissure and the posterior cornu the white substance is continuous and undivided, extending round the front and side of the cord. It is artificially divided into an anterior and a lateral column, the line of division being the outermost of the anterior nerve-roots, which pass through the front of the cord; but there is no corresponding distinction of structure, and hence it is often termed the "anterolateral column."

The white substance varies in amount in different parts of the cord, but, as a whole, lessens gradually from above downwards (see Fig. 65). It is everywhere composed of medullated nerve-fibres, which, however, possess no neurilemma-sheath. In carmine-stained sections the axis-cylinder is seen within each fibre, not always in the centre, and around this are concentric cloudy lines due to the irregular refraction of the white substance.

Between the fibres is a peculiar substance, the "neuroglia" or nerve-cement. It appears to consist of fine fibres, which form a network, embedded in a finely granular or homogeneous matrix. At their intersections are peculiar cells consisting of a nucleus and small cell body ("glia-cells," "cells of Deiters"). The fibres are generally regarded as their processes, but, according to Ranvier and