Complete Text (Part 10)

gray or white bands. The two conditions — and particularly oedema and thickening — are very often coexistent. All these changes, with the exception of simple oedema, involve discoloration of the membrane, which becomes gray or grayish-white from fibrous thicken- ing ; yellow, from pus ; red, from blood, etc. Marked dry- ness of the surface, as in the dura, points to undue pressure from within. Before drawing any conclusions from the amount of blood in the pia, it is well to remember that the distribution of the blood is greatly influenced by the position of the body, and that the fullness of the large veins in the posterior portions, which is usually present, is chiefly hypostatic. It is a notori- ous fact that beginners are very apt to diagnosticate conges- tion when it does not exist. One should, therefore, not be satisfied with a general impression, but follow up particular vessels, and notice whether they are completely or only par- tially filled with blood, whether some portion or portions of a vessel are more full of blood than others, etc. The arteries, as a rule, lie in the furrows, the veins are superficial, but when the nature of a vessel is doubtful a solution may some- times be reached, in this situation as in others, by pressing the blood out of it and noting the nature of the larger ves- sels with which it communicates directly. The capillaries not being visible to the naked eye, capillary congestion can only be diagnosticated when the red spots cannot be resolved into a collection of delicate red lines — the finest arteries and veins. Thromhosis of the larger veins is secondary to throm- bosis of the sinus. (J.) Special Morlid Conditions. 1. Hsemorrhages are met with either on the surface of the pia Qicemorrhagice iyitermeningeates')^ or in the tissue of the MEMBRANES OF THE BRAIN. 59 pia or arachnoid itself QicemorrTiagice araehnoidales, formerly- called suharachnoidales) . The former, as we have already mentioned, may come from the dura as well as the pia. That form of intermeningeal hsemorrhage which sometimes occurs in new-born children from rupture of the large veins of the pia at their junction with the sinus, in consequence of great compression and overlapping of the bones of the head, is chiefly important from a medico-legal point of view. With regard to haemorrhage in general, it may be remarked that if the blood be coagulated one is justified in drawing the conclusion that the hsemorrhage took place before death. This rule is subject to the exception that blood which was still fluid may coagulate during the progress of the autopsy if mixed with cerebro-spinal fluid. On the other hand, flu- idity is not positive proof that the blood escaped after death ; especially if the blood be infiltrated within the tissue of the pia instead of lying free on its surface. 2. Inflammation. The most common form of inflammation which is met with in the pia is arachnitis or leptomeningitis chronica fibrosa, and is characterized by thickening, whitish opacity, and, as a rule, by oedematous swelling, which latter is most strongly marked in the sulci where the membrane is thickest. The pia, when perfectly normal, lies in immediate contact with the convolutions and follows them into the sulci ; but when oedematous, its outer layer passes directly over the sulci from one convolution to another, and if the oedema be very marked may be actually separated from the surface of the convolutions by a layer of fluid. OEdematous infiltration is not always uniformly distributed, but may as- sume the form of large vesicles (oedema cysticum, hydrops multilocularis'). Pacchionian bodies are, indeed, often found without the above mentioned signs of chronic inflammation, but it is in connection with these signs that they are most numerous and attain their largest size. They form villous, gray nodules which are thickly aggregated along the superior longitudinal fissure (though at times farther outward also), and are shown by the microscope to consist of papillary col- 60 DIAGNOSIS IN PATHOLOGICAL ANATOMY. lections of connective tissue enveloped in a layer of endo- thelium. Small laminae of bone are sometimes found, but not so often as in the pia of the spinal cord. Virchow draws a distinction between superficial and deep chronic arachnitis ; the latter is the more important on account of its intimate relation with the vessels which pass from the pia into the cortex cerebri, and hence its tendency to set up inflammation in the brain tissue itself (vide meningo- encephalitis). Acute, more or less fibrinous., purulent inflammation (^arachnitis suppurativa)^ is characterized by an infiltration of the tissue of the pia with fibrine and pus, which imparts to it a whitish-yellow, or, if, as sometimes happens, the inflammatory product be pure pus, a yellow discoloration. The favorite seat of this affection being the convexity, it is sometimes called meningitis of the convexity. The pus is chiefly collected along the larger veins in the form of yellow strips of variable width ; this is especially the case in deep suppurative arachnitis., while in the superficial form the ves- sels are often completely obscured by the pus. Circum- scribed purulent inflammation is nearly always of traumatic origin. Tubercular inflammation of the convexity is rare, and if present has spread upward from the base in almost every instance. 3. Cystieerei occur in the form of cysts from the size of a pea to that of a hazel-nut, as well as in the form of yellowish- white, fatty degenerated and cretified nodules. The cysts are filled with transparent watery fluid, floating in which the naked eye can discern a whitish body about the size of a hemp-seed ; this is the head of the animal, and with the aid of a lens the hooks and four suckers can easily be distinguished. Even after the animals are dead, their presence may be de- monstrated by tearing a portion of the nodule to pieces with needles, dissolving the lime salts with hydrochloric acid, and pressing the glass cover firmly down upon the specimen ; the large hooks with their strong attachments will thus be brought to view. Cystieerei very often cause depressions on the surface of the brain and sometimes complete circum- scribed atrophy of the cortex. MEMBRANES OF THE BRAIN. 61 ' 4. We shall postpone what we have to say about Tumors till we come to the consideration of the surface of the brain itself. When the examination of the right side has been completed a small cut should be made into a fold of the dura near the left anterior extremity of the falx ; the knife should then be held like a fiddle bow, with the ends of the thumb and fingers, and its point, with the cutting edge outward, is to be inserted into the small incision ; then, the left side of the dura, the left hand meanwhile drawing the membrane away from the brain, should be divided as far as the poste- rior extremity of the falx, reflected, and examined in the same way as on the other side. One should never neglect to compare the two sides, especially as to the fullness of the vessels. Both halves of the dura should then be firmly grasped in the left hand and drawn upwards and backwards in order to put the attachment of the falx to the crista galli on the stretch. The knife with its edge directed forwards should now be passed, parallel with and to the left of the falx, down to the cribriform plate of the ethmoid ; the edge should then be turned toward the right, and the attachment severed, when the knife is withdrawn, its edge being turned forward. By drawing the membrane firmly backward the veins of the pia can be cut through at their entrance into the sinuses, and thus the whole brain as far as the tentorium be laid bare. 7. REMOVAL OF THE BEAIF FROM THE SKULL. In order to remove the hrain the opposed fingers of the left hand should be introduced under the frontal lobes, these drawn gently backward, and the nerves which are given off from, as well as the vessels which go to, the base, should be divided one after another ; in this procedure one should cut from within outwards ; i. e. against the bone. When the tentorium is reached, beginning at its right anterior extrem- ity and keeping the knife close to the bone, it should be divided by a series of short, sawing cuts, as far back as 62 DIAGNOSIS IN PATHOLOGICAL ANATOMY. possible. The same operation should then be repeated on the left side while the left hand gives the hemispheres sup- port from behind to prevent the base from being lacerated. Then, after severing the roots of any cranial nerves which may remain undivided, the knife with its edge turned to one side should be inserted as far as possible along the anterior wall into the vertebral canal, and the spinal cord be divided by elevating the handle of the knife. The knife should then be withdrawn at the side and the vertebral artery be divided at the same time.^ Lastly, the knife should be reintroduced into the canal, but this time with its edge turned toward the other side, and the operation repeated. Now, the left hand still supporting the weight of the hemispheres from behind, the right hand should be so applied to the inferior surface of the brain that the medulla oblongata rests between the fore and middle fingers, and the brain may then be raised com- pletely from the skull. The base of the skull should be examined with reference to abnormal contents. 8. THE PIA MATER AT THE BASE. The lateral and basal portions of the pia should now be ex- amined in the same manner as that of the convexity ; but special attention should be given to the great arteries, and especially the artery of the fissure of Sylvius, which should be examined in its whole course on account of its being the favorite seat of emboli, aneurisms, etc. (a.) Changes in the Great Vessels. The great vessels of the base of the brain, although of ar- terial nature, are characterized by the relative thinness of their walls ; hence any fatty or atheromatous changes in their intima can be readily seen from the outside, and are indicated by the presence of grayish, or yellowish- white spots of variable size and more or less diminution in the calibre of the vessel at the seat of the spots. The smaller branches opened longitudinally may be placed with the in- 1 If the cord has already been removed it is only necessary to divide the lat- eral attachments of the portion which remains. MEMBRANES OF THE BRAIN. 63 tima upward, under the microscope, and the cells of the inner coat are then often seen to be transformed into an- gular groups of minute, refractive, dark-contoured granules which are altered by neither acetic acid nor dilute alkalies — fatty degeneration. Aneurismal dilatation is another morbid condition which is often found, and, as has already been mentioned, occurs with greatest frequencj^ in the arteries of the fissures of Syl- vius and their branches. Such aneurisms are generally sac- cular, vary in size from that of a pea to that of a cherry- stone, but seldom exceed the latter, and generally prove fatal from rupture. They should always be borne in mind in cases of profuse hsemorrhage at the base, and the vessels carefully examined for their presence, as this otherwise might easily be overlooked in a large clot. Embolism gives rise to a third morbid condition. The plugs are readily recognizable by their dryness and pale, grayish-red color, and are most fre- quently met with either at the origin, or at the first bifurca- tion of the arteries of the Sylvian fissures ; these large em- boli generally prove rapidly fatal, and hence are but seldom adherent to the wall of the vessel. (5.) Changes in the Pia itself. The most important changes which are found in the pia of the base are those which are due to arachnitis tuberculosa, and, from the fact that they are generally confined to the base, the disease has received the name of basilar meniiigitis. The anatomical appearances consist in the presence of col- lections of a yellowish, gelatinous substance of varying con- sistency in the network of the pia within the circle of Willis, and, especially, about the optic commissure ; the exudation may, also, extend far into the fissure of Sylvius. The diag- nosis is confirmed by the discovery of minute miliary tuber- cles which seem to follow the course of the blood-vessels, and are most abundant on the under, surf ace of the frontal lobes or on the island of Reil. The tubercles may also be met with in the connective tissue of the pia apart from any vessels. For microscopical examination a small bit should 64 DIAGNOSIS IN PATHOLOGICAL ANATOMY. be cut away from the pia, and carefully separated from the surface of the brain, with the aid of a stream of water, and then the bits of cerebral substance which still adhere to it are to be removed under water with a camel's-hair brush. The tubercles may now be seen in the walls of the vessels with the naked eye, and when examined in water under the microscope appear as round-celled fusiform swellings of the adventitia. The nuclei are rendered more distinct by acetic acid and the preparation may be readily stained. Giant cells are never found in these tubercles. Purulent arachnitis is rare at the base of the brain, though not so rare as the tubercular form on its convexity ; epidemic cerebro-spinal meningitis, however, is nearly always attended with the formation of pus, and is most marked at the base. 9. EXAMINATION OF THE BEADT FROM WITHOUT. When the examination of the pia of the base has been completed, the brain should be turned over and the pia mater removed, that the surface of the brain itself may be the bet- ter seen. The best method of removing the pia is to cut through the artery of the corpus callosum near the genu in front and over the posterior border, and then seizing the intermediate portion of the vessel with forceps to detach the membrane as carefully as possible. When the surface of the convexity is reached it is better to use the finger than the forceps; but if the pia gets torn at any place it should be seized with the forceps again in a sulcus, this being the sit- uation of the larger (arterial) vessels. In case the brain is very soft the hemisphere must be supported with the other hand, meantime, to avoid injury to the corpus callosum and roof of the lateral ventricle. A hint as to manipulation may not be out of place : with the thumb on the inner and the fingers on the outer surface of that portion of the pia which has been already detached, the brain should be gradually pressed away from the membrane, from without inwards, by the finger tips and the dorsal surface of the last phalanges ; the force can thus be carefully regulated, and it is not neces- SURFACE OF THE BRAIN. 65 sary to toucli or soil the exposed surface of the brain. If cir- cumstances allow, it will be found a great assistance to let an attendant pour on water in a gentle stream. The pia is not always detached with ease, on account of more or less exten- sive adhesions between it and the brain, portions of which may remain sticking to the membrane. These adhesions are due to chronic inflammatory changes in the cortex (^encephal- itis chronica corticalis')^ which changes Virchow attributes to deep-seated chronic arachnitis, and the condition has hence been called meningo-encephalitis. It is in paralysis of the insane, so called, that this condition chiefly occurs. After the pia has been removed the general size and form of the brain can be determined (for the weight see page 75), but the general condition of the convolutions should receive spe- cial attention. The form of the convolutions is often indic- ative of changes in the brain itself; in general atrophy of the brain they are narrow and sharp on top, but they are broad and flattened from pressure against the calvaria, if from any cause the volume of the brain be increased. The amount of blood in the cortex as a whole is not easy to deter- mine from without, for the reason that the superficial vessels are torn out with the pia ; still, the presence of numerous and well-marked reddish points (puncta vasculosa) is pretty clearly indicative of congestion. Sometimes more or less extensive portions of the surface of the pia, which normally is of a uniform gray tint, present a reddish or even violet discoloration ; such portions are particularly liable to become torn when the pia is removed, and are very apt to be the seat of the adhesions of which we have spoken above. Punctate as well as moderately large hcemorrhages may be met with in any situation in consequence of injury ; they also occur in connection with recent inflammation, em- bolism of the arteries, and thrombosis of the veins second- ary to that of the sinus : in these two latter cases the ter- ritory supplied by the affected vessels is generally softened. True hsemorrhages differ from the puncta vasculosa, the pres- ence of which, to a moderate extent, is physiological, in that 5 66 DIAGNOSIS IN PATHOLOGICAL ANATOMY. the blood being effused into the tissue cannot be readily washed away. The surface of the convolutions is sometimes somewhat de- pressed and brownish in color (hsematoidine), in consequence of old injuries, and Virchow has found the ganglion cells of the cortex cretified in these plaques