Complete Text (Part 11)

jaunes. By tearing a small bit of the cortex with needles, in a drop or two of water, and pressing lightly on the cover glass, a specimen is readily prepared for the microscope. The ganglion cells are, as a rule, recognizable from their pyramidal shape. Local, circumscribed lesion of the surface may also depend on the presence of the following tumors : tubercular nodules^ wrongly called solitary tubercles, gummata, and sarcomata, the last of which are generally larger than either of the other two. The differential diagnosis is often very difficult, and sometimes impossible, or rendered possible only by the condition of other parts. The most distinctive characteris- tic of tubercle is the presence of gray submiliary tubercles in the grayish transparent zone which surrounds the yellow and cheesy centre ; these miliary tubercles are easily isolated with the aid of needles, and often contain enormous giant cells. Again, tubercles are more entirely and uniformly caseous than gummata, the cheesy portions of which are either surrounded or penetrated by more strongly marked zones of tissue of varying consistency. Finally, tubercles — the larger ones, at all events — show central softening much oftener than gummata, although the surrounding cerebral substance is more liable to softening in syphilis than in tu- berculosis. The distinction between sarcomatous or glio-sar- comatous and syphilitic growths, is often attended with the greatest difficulty, for the reason that the sarcomata are so prone to partial fatty degeneration. A tumor which is com- posed of a gray and transparent or tough and fibrous ground- work, with numerous yellow and homogeneous masses scattered through it, — and especially if these masses are relatively dense, — may, nevertheless, be regarded as of syphilitic origin. Needle preparations of gummy tumors in the fresh state INTERIOR OF THE BRAIN. 67 show either richly cellular granulation tissue or tough cica- tricial connective tissue with clearly defined spindle and stellate cells. The yellow portions are seen to consist of a compact and amorphous groundwork which is here and there striated, and great numbers of small fat drops, but no true granular corpuscles are to be seen ; these, on the other hand, are usually very prominent in the fatty degenerated portions of the sarcoma, and occur isolated in the groundwork of the tumor. . The tissue surrounding a sarcomatous growth often contains large and highly developed cells, but that surround- ing a gummy tumor does not. Oysticerei are also found in the cerebral tissue, and when in the stage of fatty degeneration and cretification might give rise to error in diagnosis, were it not that they are invested by a tough capsule of connective tissue ; their microscopical characteristics we have already described. 10. EXAMINATION OF THE INTERIOR OF THE BRAIN. The time has now arrived for cutting into the brain, which should be opened in such a way as to permit the examina- tion of the ventricles first and then of their neighboring parts. (a.) Examination of the Ventricles of the Cerebrum. The brain being placed in the position which it occupies in the body in the erect posture, a shallow vertical incision should be made in the roof of the left lateral ventricle about one or two millimeters from the raphe of the corpus callosum (the incision should not be too deep lest the great ganglia be injured), and prolonged backwards and outwards into the posterior cornu as well as forwards and somewhat outwards into the anterior cornu. The two extremities of the cut should then be connected by another vertical cut outside of the great ganglia to the depth of the cortex of the inferior surface, and the left hemisphere will then be laid to one side like a prism which is convex on its under surface. The brain should then be turned round, and the right hem- 68 DIA GNOSIS IN PA THOL 0 GICAL ANA TOMY. isphere treated in tlie same manner. The lateral ventricles are now exposed, together with their anterior and posterior cornua, and are to be examined with reference to their size^ contents (a teaspoonful at most in the normal state), and the condition of the ependyma. 1. Dilatation of the ventricles, due to an accumulation of clear watery fluid, but very seldom of pus, is called internal, or ventricular TiydrocejjJialus, and may be either congenital or acquired. If the latter, it may be either of inflammatory or purely mechanical origin, — pressure of a tumor of the cere- bellum on the vena Galeni, for instance. In acquired hydro- cephalus the skull is rigid, and thus the brain, especially the white portion, becomes greatly atrophied ; in the congenital form, however, the skull which is still growing yields to the pressure of the dilated brain, and becomes larger itself. Abnormal openings are, indeed, sometimes thus caused in the skull, through which the brain may project under the skin : the favorite seats of this condition (hydrencephalocele') are the occipital regions and the lower portion of the frontal. These tumors do not always contain brain substance, but may be due also to a high degree of cystic oedema of the pia mater (Jiydromeningocele^. Hydrencephalocele in its highest development constitutes the condition known as acrania or anencephalia, in which the whole bony vault of the skull is wanting, or else only vestiges of it remain, and sometimes the brain itself is in large measure destroj^ed by rupture of the surface of the tumor. Spina bifida is often coexistent with this condition. 2. The normal ependyma forms a thin, smooth, colorless, and translucent investment of the inner walls of the ventri- cles, but may, pathologically, be either softened, or hardened and thickened. In chronic hydrocephalus it is generally softened, and may be separated from its attachments in the form of a coherent gelatinous mass. On the other hand, it is hardened in chronic conditions of the brain substance, at- tended with induration, such as sclerosis, and may resemble the toughest connective tissue in density (ependymitis chron- INTERIOR OF THE BRAIN. 69 ica) ; it is then usually thickened, either generally or locally, in the form of small nodular or warty prominences (ependy- mitis proliferans). These local thickenings are common enough in all sorts of conditions, and are usually associated with thickening of the pia mater ; in the lateral ventricles their favorite seat is along the border of the corpora striata at either side of the septum lucidum, but they are still more common in the fourth ventricle. They often appear like minute dew-drops, and then might be mistaken for very young tubercles, but they may attain the size of a hemp- seed, and, in rare cases, even of a pea. When torn to pieces, and placed in water under the microscope, they are seen to consist of a close network of the most delicate connective tissue fibres, which swell when placed in acetic acid, and enclose a variable number of cells, and, as a rule, great num- bers of corpora amylacea. The ependyma may become ad- herent in consequence of chronic inflammation. Such ad- hesions are usually only partial, and are chiefly met with in the posterior cornua : the peripheral portion of the cornu is thus shut off from the central cavity of the ventricle, and hydrocele of the posterior cornu results: there may be a series of these detached cavities. A rich network of large veins lies under the ependyma of the lateral ventricles, and these veins communicate with the vena magna Galeni through the velum interpositum. Small multiple hsemorrhages are not very unfrequently found in and under the ependyma, especially in cases of arachnitis tuber- culosa. If it be desired to obtain a view of the middle or de- scending cornu, and the pes hippocampi, the former must be cut into externally to the optic thalamus. The choroid plexus can be easily raised from its place and examined. The amount of blood which it contains should be noted as well as the presence of any pathological conditions, the most common but least important of which are cysts containing clear fluid, and varying in size from that of a millet-seed or pea to that of a cherry-stone ; these are not to be mistaken for cysticerci, which may also be found in this situation. 70 DIAGNOSIS IN PATHOLOGICAL ANATOMY. To open the third ventricle^ the corpus callosum and the fornix should be severed from below upwards and the pos- terior portions reflected backwards ; in doing this they are to be raised up midway in their course, and the knife is to be passed into the foramen of Monro. The ventricle is still hidden by the velum interpositum ; the handle of the scalpel should be inserted under this, and it should then be likewise reflected from before backwards over the pineal gland and the corpora quadrigemina, the presence or absence of congestion or other morbid conditions being noted. In basilar meningitis, tubercles are sometimes found in the velum interpositum and choroid plexus, but are recognized with difliculty, from the fact that small papillary growths greatly resembling tubercles occur normally in these situa- tions. They can be distinguished microscopically from tuber- cles by placing the suspected portion on a dark colored sup- port of some kind ; if they are tubercles they will be seen to lie along the course of the vessels. The condition of the velum interpositum should receive special attention in all those cases in which abnormal contents are found in the ven- tricles, for the reason that effusions generally, though not invariably, come from the velum interpositum. The part played by the vena magna Galeni in those cases of hydroce- phalus which are due to passive congestion, has been already alluded to. (5.) The Cerebrum. 1. Examination of the Hemispheres. Supporting the everted left hemisphere in the palm of the left hand it should be laid open by long, straight, vertical incisions extending to the depth of the cortex ; the little fin- ger, meanwhile, being kept immediately under the place where each incision is made, and serving by a slight upward movement to make the two surfaces of the cut fall apart ; thus all danger of injuring or soiling the parts, whether with knife or finger, is avoided. By taking care to make the in- cisions always along the upper edge of the ridges which result from the cuts made in the previous stage, the whole white INTERIOR OF THE BRAIN. 71 substance can be thoroughly examined. The cuts should not be so deep as completely to sever the connection of the parts, but should be deep enough to expose the cortex in various places. The brain should then be turned round, and the right hemisphere treated in the same way. The degree of moisture of the cut surface is to be noted — whether glistening with the moisture of oedema, or dry, — as also the number and size of the red spots (^puncta cru- entd) where the blood-vessels have been divided. These red spots differ from punctiform haemorrhages in that they can- not be permanently washed away, while the latter can. If, after washing with a stream of water, the red spots reappear rapidly and in great numbers, considerable injection of the vessels of the white substance is present. It is very impor- tant to note the relative proportion both of one hemisphere to the other, and of the white and gray portions of each hemisphere ; but, above all, the width of the cortex should be noted. By noting whether the white and gray portions occupy the same level on the cut surface, one is greatly as- sisted in determining the presence of either swelling or atrophy of one or the other portion. The most important form of atrophy is that which is characterized as senile., and affects chiefly the cortical portion. The causes of swelling or enlargement are threefold : 1st. simple hypercemia., as indi- cated by the color of the brain, and the large size and num- ber of the pun eta cruenta ; 2d. oedema, as indicated by ex- cessive moisture of the cut surfaces ; 3d. inflammatory pro- liferation of the neuroglia. The last form may be called parenchymatous enlargement, and is especially common in young children. It is very difficult, and sometimes even impossible, to distinguish the two last forms from each other. ( Vide Encephalitis neonatorum.) We shall have something to say about circumscribed lesions at the close of our remarks on the examination of in- dividual portions of the brain. 2. Examiyiation of the G-reat Ganglia. The great ganglia, the corpora striata and optic thalami, 72 DIAGNOSIS IN PATHOLOGICAL ANATOMY. may be laid open either in the direction of their fibres by in- cisions radiating like the sticks of a fan from the peduncle, or by simple transverse incisions. The latter method is better suited for instituting a comparison between the two sides, and is best carried out by cutting through corresponding portions of the ganglion of either side at one incision ; for this purpose a large thin-bladed knife should be used. In order to make the cut surfaces fall well apart the left hand should be introduced under the brain, and the tips of the fingers in close apposition should be placed under the por- tion where the incision is being made ; by then raising the finger tips slightly the cut is made to gape open widely. There is normally a lack of uniformity in the grayish shade of the ganglia : the corpus striatum, and particularly the outer zone of the nucleus lenticularis are darker and rather brownish in color, while the two other zones of the nucleus lenticularis as well as all three of the optic thalamus are lighter and of a more yellowish-gray. (c.) The Fourth Ventricle. In order to spare the fornix, it, together with the velum interpositum and the pineal gland, should be laid over to the left ; the corpora quadrigemina are thus exposed to view, and may be laid open by transverse cuts. The left hand should then support the cerebellum from below, and an incision be carried along the vermiform process, remembering that the cavity of the ventricle lies deeper behind than in front. If the cut has been made exactly in the median line, the aque- duct of Sylvius will also be opened to view. The fourth ven- tricle is to be examined with reference to the same points as the other ventricles have been. The granvilar thickening of the ependyma, which is so often found here, has been already alluded to, and we should not neglect to note the degree of prominence of the auditory striae. INTERIOR OF THE BRAIN. 73 (d.'y The Cerebellum. The hemispheres of the cerebellum., which have ak-eady been sep9,rated by the cut which opened the fourth ventricle, should now be further divided, one at a time, by a cut extending from the ventricle in the direction of the middle branch of the arbor vitse, and through the substance as far as the con- vexity ; the surfaces resulting from this cut are fan-shaped, white at the centre, and gray at the periphery. The corpus dentatum is seen imbedded in the white matter, and sur- rounded by a delicate gray capsule. The examination of the cerebellum, and at the same time of the brain from above, is now to be completed by cuts radiating out from the cerebellar peduncle. (e.) The Pons and the Medulla Oblongata. It only remains to open the pons and the medulla, and to examine the cranial nerves. In order to do this the hemi- spheres should be folded together like the leaves of a book, thus restoring the brain to its normal shape, and then, the palms of the hands being placed under the sides, it should be turned over on its transverse axis. If it be desirable to investigate the condition of special vessels more minutely this can still easily be done, and then the size and color (whether grayish or not) of the nerves should be noticed ; finally the pons and medulla oblongata are to be cut ti-ans- versely while the left hand supports them from beneath. In the cerebellum and in these parts, just as in the brain proper, the points which should receive special attention are the color and the amount of blood. It is advisable in all cases, and absolutely necessary when calcification is present, .to dissect off the vertebral and basilar arteries from behind, and then lay them over forwards before cutting into the pons. 74 DIAGNOSIS IN PATHOLOGICAL ANATOMY. (/.) Other Methods of laying open the Brain. It is not always necessary and may be undesirable to cut up the brain in the minute manner which we have laid down above ; especially when a local affection which can be recog- nized from the outside — tumor, abscess, large effusion of blood — is present. For the sake of the clinical interest which attaches to such cases the attention should be chiefly directed to determining the size and exact seat of the lesion, what portions of the brain are completely disorganized by the same, and what portions are only secondarily affected in consequence of pressure, softening, etc. The best method of procedure in these cases is — without removing the pia or making any other cut at present — to make a transverse cut completely across the brain and through the middle of the lesion with a long and thin-bladed knife, thus laying open the healthy as well as the diseased hemisphere, at as nearly the same level as possible, and securing a standard of comparison. A general view of the seat, extent, and na- ture of the lesion may thus be obtained, but, if it be de- sired to pursue the examination further, it will be found of advantage to harden the brain before doing so, for the reason that the diseased portions are usually so soft that