CHAPTER XVII. PATHOLOGY AND PATHOLOGICAL ANATOMY. (Part 1)

CHAPTER XVII. PATHOLOGY AND PATHOLOGICAL ANATOMY. Pathological Anatomy. {a) Macroscopic. The Brain. — The bone of the calvarium is in a pro- portionate number of cases, one third in the large series observed by Mickle, increased in thickness and density, with disappearance of the diploe. In a much less number it is thinner than normal, and very rarely it is abnormally soft. Often, also, the bone is con- gested and its inner surface may have a worm-eaten appearance. Occasionally there may be a distinct deposit of new bone, either in the form of a layer, or of one or more exostoses, on the inside of the inner table. The dura is frequently thickened and vascular, sometimes but slightly. According to Mickle this change is found in about one half the cases. In a smaller number, one fourth, it is also more or less tenaciously adherent to the bone, between which also (dura and bone), there may be numerous vascular connections, consisting of thickened and tortuous , vessels. The internal surface of the dura often shows evidences of internal pachymeningitis, usually of the hemorrhagic variety. This may be evidenced by either the existence alone of the characteristic false membrane and reddish-brown stainings, which mark the seat of previous hemorrhages, or more rarely, in addition marked hematomata, which may be present either externally, or internally, or both. 246 THE BRAIN. 247 In the subdural space there is an increase of cere- brospinal fluid, which may be either pellucid or turbid. The arachnoid is always more opaque and usually is much thicker and tougher than normal, and either mottled with white spots, or striated along the fissures with white fibrous appearing bands. These changes are more marked over the fronto-parietal con- vexity and internal surface of the hemispheres, and often the interpeduncular space is bridged by a tough thickened arachnoid. Calcareous plates are occasion- ally found in the membrane. Under the arachnoid, especially over the fronto- parietal regions of the brain, are seen covering the pia numerous varying sized dilated and congested vessels, lying in what appears like a milky or opaque jelly; if the arachnoid is perforated this material oozes out as a dirty opaque fluid. The pia is greatly thickened and may occasionally contain, either small bony plates, firm, fibrous, whitish nodules, or a few patches of lymph or pus. When the membrane is removed from the brain substance an intense edematous con- dition is found everywhere present, both in the fissures and over the surface of the convolutions and per- meating the cortical substance. The membrane no longer readily separates from the brain cortex, but is adherent to it, especially over the apices of the con- volutions, and the attempt at removal brings away also bits of the adherent cortex. These changes are well shown in Plate XII. The lobes of the brain, also, often are adherent one to the other, such cohesion being especially common between the frontal lobes. In very acute cases these cerebro-meningeal adhes- ions may be absent and the meningeal changes con- sist of a slightly opaque arachnoid, an edematous and congested pia. In such cases the brain may appear to be increased in volume, owing to the intense 248 PATHOLOGY AND PATHOi-UlilCAL ANATOMY. congestion and edema and, if the dura is removed, it may be impossible, owing to the projecting brain, to replace the calvaria. These changes, instead of involving entire lobes, may be confined to isolated areas. In the more chronic forms, which are the more common, the brain is more or less flaccid, smaller and lighter than normal. The appearance of the brain cortex varies, the changes being most pro- nounced in the frontal region and shading off gradu- ally toward the normal, as we pass backward. The one practically constant feature, ninety-four per cent, in Mickle's series, being that it is much reduced in thickness. The convolutions are also thin, shrivelled, or flattened. It may be softer, either in whole or in parts only, more rarely it is indurated, either in small areas, or diffusely, when it gradually shades off to normal, or to lessened consistence as we examine from the frontal towards the occipital region. Usu- ally it is the seat of areas of hyperemia of more or less irregular distribution, but may be anemic. In the former case its color would be reddish, in various degrees, or mottled, while in the latter it is either pale, fawn color, dirty white, or slate colored. The strata are often indistinct. The cortex is found hyperemic and softened in cases of comparatively brief duration, the longer the course of the disease the more apt we are to find it indurated and anemic; some authorities, Clouston and Berkley among others, describe the latter as the condition more commonly met with. Where the pia has been adherent the convolutions present an irregularly eroded appearance; as Clouston expresses it, they resemble the surface of a cheese where a mouse has been. This tearing off of the cortex has been termed decortication. The erosions may be red in color, or THE BRAIN. 249 pale, according to the progress of the disease. They are most common in the frontal and parietal lobes and the gyri about the olfactory bulbs at the base, but may occur elsewhere. Mickle claims that they do not always correspond to the adhesions on the sum- mits of the gyri, but may be found at the bottom of the fissures. Sometimes the entire depth of the gray matter comes off, leaving the white matter beneath. Decortication in greater or less degree, is the most characteristic and frequent of the gross lesions of paresis, but is not pathognomonic. The white matter, as the gray, may be either of diminished consistence, when it is hyperemic and reddish, or mottled in color; or of increased consist- ence, when it is of an unnatural whiteness and may display a sieve-like appearance. The ventricles are dilated, filled with fluid and the ependyma is thick- ened, roughened and tougher than normal. In marked cases it is covered with granulations and feels dis- tinctly rough to the touch. This condition is usually most marked in the floor of the fourth ventricle and there it often presents a grayish gelatinous appearance. The ganglia at the base of the brain are often atro- phied and they may be either softer or harder than normal. The pons and medulla^ may also in some cases be the seat of morbid changes, either softening or induration being present, more rarely distinct atrophy may be seen. Similar changes arc sometimes found in the cere- bellum. Mickle claims to have found adhesions ot the membranes to the cerebellum in forty-four per cent, of his cases. Other writers deny that cerebellar adhesions occur. * That the pons and medulla are anatomically parts of the spinal cord is believed by the writer, but as in most text-books they are considered as parts of the brain, they are here so included and will be, also, when the microscopic changes are described. 250 PATHOLOGY AND PATHOLOGICAL ANATOMY, The olfactory bulbs and tracts are often atrophied and soflened, and similar changes have been found in the optic nerves. The prominent macroscopic changes in the brain and its membranes may be summed up as follows : 1. Thickening of the dura, with internal hemor- rhagic pachymeningitis (about fifty per cent, of the cases). 2. An increase of the fluid in the subdural space and meshes of the arachnoid. 3. Opacity and thickening of the pia with adhe- sions to the cortex, causing portions of the cortex to adhere to the membrane, when it is stripped off (decortication). 4. General flaccidity and diminution of the weight of the brain and marked narrowing of the cortex. 5. Areas of softening and hyperemia and of undue firmness and anemia scattered over the cortex. 6. Dilatation of the ventricles, thickening and roughening of the ependyma and increase of fluid within them. The Spinal Cord. — As has been noted in discussing symptomatology, the prominence of spinal symptoms varies. In those cases in which they are slight, the morbid anatomical changes present are slight, in those in which they are prominent, the changes in the cord and its membranes are likewise prominent. Alterations of some sort arc found in most cases. The following changes may be present. The men- inges are often thickened and hypcremic, opaque, granulated and adherent to each other and to the cord. These appearances are more apt to be found posteriorly. In a small number of cases evidences of hemorrhagic pachymeningitis, in the shape of re- cent or old clots, may be found. Clots are some- times also found extra-dural. THE BRAIN. 25 1 The thickened pia surrounds the spinal nerves as they emerge, forming, as Mickle expresses it, muffs for them. In acute cases the spinal membranes may be red- dened, thickened, somewhat opaque and markedly edematous. Mickle found in two thirds of his cases softening of parts of the cord; in one third, he found induration and in from ten to twelve per cent, atrophy. Either hyperemia, or pallor of the cord substance, may be found in a few cases. In a^considerable number of cases, 15.9 per cent, according to Bevan Lewis, sclerosis of the posterior columns and of the dorsal and lumbar posterior nerve roots, with thickening of their sheaths, similar to that in tabes, is found. When found, the sclerosis is usu- ally most marked in the lower part of the cord, becoming narrower and more confined to the columns of Goll as it ascends, to cease at the floor of the fourth ventricle. In other cases the sclerosis is con- fined to the posterior commissural zone and the pos- terior median columns (columns of Goll), the root zones escaping. ' More rarely a secondary descending degeneration of the pyramidal tracts occurs either alone, or asso- ciated with the posterior sclerosis. Either a diffuse slight sclerosis, causing generally increased hardness, or a slight diffuse myelitis, causing general softening, may be occasionally present. Atrophy of parts of the gray matter, especially the horns, is sometimes present. (d) Microscopic. The Brain. — The microscopic changes found in gen- eral paresis are manifold; none however are strictly characteristic of the disease and it is doubtful if it 252 PATHOLOGY AND PATHOLOGICAL ANATOMY. can positively be diagnosed with the microscope.^ The main interest, of course, attaches to those found in the pia and cortex. These changes may be classi- fied as follows: 1. Those in the blood-vessels of the cortex and pia, and the perivascular or lymph-spaces. 2. The neuroglia. 3. The nerve cells and fibers. I. The Blood- Vessels — The walls of the capillaries are thickened and present a granular appearance, with an increase in the number of nuclei that are normally present there. (See Plate XIII., Fig. 2.) Fre- quently there is some migration of leucocytes, which are founcl in the perivascular spaces. The adventitia of many of the pial and intra- cerebral arterioles is, according to the state of the disease, infiltrated more or less densely with small round cells, which in marked examples are found also in the neighboring nervous tissues. In advanced cases the cells may be so dense that the vessel wall is hidden; indeed, Mickle has compared the appearance to that of a muff surrounding the vessel. This infil- tration is probably due to a periarteritis. (Plate XIIL, Fig. 3.) The perivascular, or lymph spaces finally become full of these cells, so that finally many of them become impervious to the passage of the lymph. Hematoidin and cellular debris are also found in these spaces. Some, owing to the pressure of the fluid in attempt- ing to get through, are dilated. In addition to the vessels so affected W. Ford Robertson* lays stress upon the large numbers of capillaries and arterioles that are affected with that form of degeneration known as hyaline fibroid degen- 1 Vid€ O. Schmidt, AUgemeine Zeitschrift fUr Psychiatrie, 54, 1897-. 1898, p. 178. 'Pathologj of Mental Diseases, p. 140 et seq. THE NEUROGLIA. 253 eration, orarterio-capillary fibrosis; this, while present to a greater or less extent in all persons after middle life, is especially prominent in cases dying of general paresis. It is characterized by the proliferation of the endothelial cells, the formation of new fibrous tissue, and finally by a hyaline degeneration of these cells and fibers, causing the vessel to present a thick- ened, vitreous appearance. In the arterioles and venules affected with this form of degeneration the adventitia is converted into a broad, homogeneous band of regular outline. In these vessels there is also usually some degeneration of the middle coat. The short vessels of the first layer of the cortex are particularly affected. Other vascular changes, not so commonly met with, are pigmentation of the vessel walls; dilatation of the vessel ; obliteration or narrowing of the lumen. 2. The Neuroglia. — Those elements of the neuroglia known as Deiters', or spider cells present marked changes in the affection that we are considering. Bevan Lewis* terms these cells and their processes the " lymph connective tissue of the brain '' and first advanced the view that they play some part in " the reabsorption and distribution of the effete material and surplus plasma.'' By means of methods de- veloped by him, it is found that these cells throw off two sets of processes: (i) "An enormous number of extremely delicate fibers, which spread into the intervascular area around, and (2) a much thicker, coarser process, which often, after a tortuous course, ends in the adventitial sheath of the blood-vessel." (See Fig. 4.) These processes, in crossing the perivascular canal, give off a number of delicate proc- esses that traverse the canal. This view of the > Mental Diseases, 2d Edition, p. 98 et seq. 22 254 PATHOLOGY AND PATHOLOGICAL ANATOMY. ENQER-CELLS. SECTION FAOM FIFTH CORTtOAL LAVER OH MOTOR REQION. X21CL (BCVAN LEWIS.) THE NERVE CELL. 255 function of these cells has been accepted by other, but not by all pathologists. In general paresis there is a general hypertrophy of this system, the cell body becomes considerably en- larged, often exhibiting subdivisions of the nucleus, and stains much more deeply with aniline than does the normal cell.^ The processes also stain deeply and the vascular processes, which stain still more deeply (those attached to the blood-vessels), are in- creased in size and often in number and are seen to be attached to the vessel by a nucleated mass of protoplasm. The other processes are often seen to surround and embrace the nerve cells. (See Fig. 4.) These changes occur in the later stages after the perivascular spaces have become blocked up, (see p. 252) and it is proper to state are not always found markedly developed. In a series of sixty-four cases, examined by Ford Robertson, only one third showed them to a great degree. According to Bevan Lewis * they are due probably to an effort of these cells to remove the effete materials and cellular debris that are found in the brain from degenerated nerve cells, and whose removal is hindered by the obstruction of the perivascular spaces or lymph chan- nels. He often speaks of them as " scavenger cells.'' 3. The Nerve Cell. — Various forms of degeneration of the neurone are met with, all of which may also be found in other conditions. That most commonly met with is the pigmentary or yellow globular. Bevan Lewis was the first to lay stress upon this form, which he termed pigmentary or fuscous. It consists in the early stages of the formation below the nucleus of a quantity of yellow pigment; at this time also the iNormalljrthe cell body and processes, 1. e., Deiters' cells, do not stain at all with aniline, the nucleus alone staining faintljr. ^JLoc, cit.f p. 183. 256 PATHOLOGY AND PATHOLOGICAL ANATOMY. cell body becomes swollen, and the protoplasm stains more deeply than normally. As the process con- tinues the amount of pigment increases, the nucleus is displaced and even it sometimes becomes pig- mented. The protoplasm stains more faintly than nor- mally (chromatolysis) and the processes begin to dis- appear until finally none are left, the nucleus disin- tegrates and the cell becomes a mass of translucent colorless finely granular material that practically does not stain at all. (See Plate XIII., Fig. 5.) Bevan Lewis believes that the pigment accumula- tion is " invariably a witness of bygone functional activity" and that its increase is due to an over- activity of the cell. This view is also held by Schafer, but is combated by many pathologists, not- ably Marinesco and Robertson. The different stages in the process have been well summarized by Bevan Lewis^ thus: Period of Over- Activity? — (i) Swelling of cell with increase of pigment. (2) Advancing degenera- tion, cell more globose, protoplasm retracting. Scle- rotic investment of cell and cincture formed. Period of Diminished Activity. — Nucleus eccen- tric, deformed, fatty, with narrow encircling zone of protoplasm. Processes few; these, as well as cell- protoplasm, faintly stained. Period of Absorption. — Fatty transformation and decoloration of cell. Atrophy with shrinking or rup- ture into a heap of granules. Agapoff, who examined the brains of six cases of general paresis, lays stress upon the number of the 1 For further description of this process see Mental Diseases, 2d Edition, Bevan Lewis, p. 527 et seq.; W. Ford Robertson, Pathology of Mental Diseases, p. 243 et seq. *It must be borne in mind, as has been before stated, that many pathol- ogists do not believe in the existence of a period of over-activity, but that the entire process is due to one of diminished activity. THE NERVE CELL. 257 pyramidal cells in which the gemmules of the den- dritic processes were either lost entirely, or were diminished in number.^ There is also disappearance of the medullated fibers in portions, principally the frontal and antero-parietal of the cerebral cortex. There is