be noted before the calvaria is removed. <Callout type="important" title="Important">Carefully note any adhesions between bone and dura to avoid injury.</Callout> 4 50 DIAGNOSIS IN PATHOLOGICAL ANATOMY. the bone through the temporal muscles and other soft parts which still remain, from the glabella to the occipital protuberance, and the bone then sawn through in this line, care being taken not to injure the brain. ^ A great saving in labor can be effected by sawing only partially through the bone and completing the work with the mallet and chisel. The latter should then be inserted into the track of the saw, and a turn of the handle will generally suffice to remove the calvaria entirely. Slight pathological adhesions between the bone and the dura, such as are chiefly met with in the frontal region, can often be broken up by trying to pry off the calvaria from behind forward instead of from before backward ; but if, as is common enough, the adhesions be strong or extensive, the calvaria and dura must be removed together. In order to do this the dura should be divided in the track of the saw, and then its attachment to the crista galli should be put on the stretch by drawing the frontal portion of the calvaria firmly backward, when it may be severed. This method must also be followed in children under seven years of age, for the reason that in them the dura still serves as internal periosteum and is hence firmly adherent ^ to the bone. The dura can then generally be torn from the bone, though it may be necessary to use a little force and the examination can be continued in the usual way. In case, however, that it cannot be torn off even then, all idea of examining the inner surface of the bone and the outer surface of the dura must be given up, and the longitudinal sinus should then be opened. 1 "When it is desirable to avoid the chance of disfiguring the corpse this in- cision should be wedge-shaped, the apices of the wedge being at the base of the mastoid processes. The temporal fascia adhering to the calvaria should be united by sutures to that portion attached to the lower part of the skull. Eev. 2 The examination of the brain can be much simplified in many cases, and particularly in young children, in whom the brain is normally softer than in adults, by the adoption of Griesinger's method, which consists in sawing through the bone and brain together. The injury M^hich the brain receives thereby is but trifling ; often, indeed, less than when the usual method is followed. CRANIUM. 51 3. EXAMINATION OF THE BONE FROM WITHIN. (a.) By examining the sawn edge of the calvaria informa- tion may be gained as to its gross thickness., as to the relative thickness of its several parts — outer table, diploe, inner table — and as to the amount of blood present. The cal- varia should also be examined by transmitted light in order to ascertain from the degree of translucency and color the thickness of the skull in general, and that of the diploetic portion in particular, as well as the amount of blood in the latter. Although we shall postpone the description of the various morbid changes which may occur in these parts till we come to the bones of the extremities, we must call atten- tion here to the importance of carefully noting the coloration of the diploe. A greenish-yellow or slaty discoloration of the diploe suggests the existence of severe inflammatory affections (as osteomyelitis, particularly its infective form) whose presence might otherwise be overlooked owing to the small amount of cancellated tissue present. (5.) The inner surface should next be examined, and its configuration be noted ; this may be varied by the presence or absence of juga cerebralia, hyperostoses, exostoses, digital impressions, abnormal depressions due to internal atrophy, etc. Depressions on either side of the longitudinal groove caused by the Pacchionian bodies are nearly always present ; these are of very subordinate importance, although the bone may be actually perforated. The width and depth of the grooves in which the meningeal arteries lie should also be noted ; these may be deepened by internal hyperostosis, though it should be remembered that their normal limit of variation is very wide. The color of the surface, which in the normal state is a grayish-yellow, should be carefully noted, for the reason that discoloration is often the sole indication of the presence of a morbid condition. I refer particularly to that chalky-white discoloration which occurs in isolated spots in the form of a network, and depends on the presence of osteophytes which 52 DIAGNOSIS IN PATHOLOGICAL ANATOMY. are so little elevated above the surface as, otherwise, easily to escape detection (puerperal osteophytes of the frontal bone, etc.). The presence of adherent coagula on any por- tion of the inner surface of the skull should always awaken suspicion of fracture through that portion, and induce fur- ther careful examination. 4. THE DUEA MATEE OF THE CONVEXITY FROM WITHOUT. (a.) The Membrane itself. On the removal of the calvaria the dura mater comes into view, and is to be examined with reference to its thick- ness, tension, color, and amount of blood. The thickness of the dura is indicated by the greater or less distinctness with which the veins of the pia and the convolutions are visible through it. The veins have a bluish color, the convolutions a yellowish gray, and both can, in the normal condition, be everywhere clearly distinguished. The degree of tension should always be tested near the anterior margin, for the reason that posteriorly the membrane is put on the stretch by the gravitation of the brain against it. In the usual position of a body (on the back), one should be able to raise up the membrane in a small fold near the apex of the fron- tal lobe ; if a pretty large fold can thus be lifted, the con- tents of the skull are diminished ; if no fold at all can be raised, they are increased (hemorrhage, hydrocephalus, tu- mor, abscess, etc.). The membrane is commonly gray in color^ but grows whiter as it increases in thickness. It is only the larger vessels, and particularly the arteries, which contain blood, as a rule ; the arteries are easily recognizable as such by their venas comitantes. Sometimes, the smaller vessels also are full of blood, but the membrane is relatively so feebly vascular that it does not, even then, appear very red ; another consequence of this anatomical peculiarity is that the membrane is never reddened around recent injur- ies. Haemorrhage between the dura and the bones is called extrameningeal, and may be of traumatic origin, even though MEMBRANES OF THE BRAIN. 53 the bone itself be intact. One of the most common affec- tions of the external surface of the dura, is ossifying inflam- mation Qp achy meningitis externa ossificans^, which renders the membrane firmly adherent; if it then be forcibly de- tached, fibrous shreds remain adherent here and there to the bone, which shreds are portions of the dura itself and are not to be confounded with new-formed false membranes as found on serous surfaces. Purulent inflammation {jpacliy men- ingitis externa purulenta) is less common on the convexity, and is usually dependent on injuries in which the bone may or may not be involved. The membrane is then thickened, opaque, yellowish in color, and covered with a thin film of pus which is never found in large quantities. True syphilitic inflammation (^pachymeningitis externa gummosa') is generally associated with similar changes in the bone. Recent gummata are yellowish-gray in color, and have a gelatinous appearance; older gummata present this gelatinous appearance only at their periphery and contain in their interior bright yellow masses of irregular form. Needle preparations of the recent formations show great numbers of round and spindle cells ; those of the old and yellow forma- tions contain great numbers of fatty degenerated cells and fatty detritus. Tubercular inflammation is rare and always associated with tubercular change in the adjacent bone. The true new formations which are met with in the dura will demand consideration in another place, and here I will only call attention to those small gray nodules consisting of several rounded lobules which are so often seen near the longitudinal sinus in a spot corresponding to the anterior extremity of the sagittal suture. These appear to be out- growths from the dura, but in reality have made their way through it and belong to the pia (Pacchionian bodies'). (5.) The Longitudinal Sinus. The longitudinal sinus is now to be opened ; its superior wall should be made tense with two fingers of the left hand, and then be divided with the knife, the blade of which should be kept parallel with the surface of the membrane. Some- 54 DIAGNOSIS IN PATHOLOGICAL ANATOMY. times the sinus is found empty, sometimes it contains fluid, or freshly coagulated blood. It may not be amiss to men- tion the fact that not infrequently the Pacchionian bodies penetrate the inferior wall of the sinus, and project into its cavity without causing further trouble. When the dura is more or less forcibly removed, they are often torn off with it, and one might be deceived into regarding them as por- tions of it ; but if the dura is carefully dissected off they re- tain their connection with the pia, and the former is found to be perforated at its points of contact with these bodies : the same thing may also occur on other portions of the dura. Occasionally the longitudinal sinus contains a more or less decolorized old blood clot which may be firm through- out or softened at its centre, and more or less adherent to the wall (thrombosis of the sinus'). This condition is gen- erally met with in children, and results from general disturb- ances of the circulation (marantic thrombosis) ; while throm- bosis of the transverse sinus is more phlebitic in nature — as, for instance, in caries of the petrous bone — and affects adults. 5. THE DURA MATEE. OF THE CONVEXITY FROM WITHIN". The dura of the right side should be divided near the sawn edge of the bone from one extremity of the falx to the other, the blade of the knife being kept as nearly parallel with the surface as possible, and the left hand drawing the upper portion of the membrane away from the brain as pre- cautions against injuring the latter. The portion which is thus partially separated from its attachment should' be then reflected over on the opposite side, so that its whole inner surface is exposed to view. If adhesions between the dura and the pia are present, they are to be divided. (a.) General Appearance and Character. The color of the inner surface is like that of the outer, sometimes gray, sometimes whitish. A common pathologi- cal condition consists in the presence of a more or less marked brown discoloration which may be diffused over a pretty MEMBRANES OF THE BRAIN. 55 large surface or limited to smaller circumscribed patches, but generally occurs in the form of more or less minute specks (hasmatoidine formed from old ha3morrhage). Most of the modifications of color are due to blood within or without the vessels. The vessels of the dura in its normal condition, are small and form a coarse network ; whenever they are rela- tively large and closely interwoven, they are to be regarded as newly formed. Hoemorrliage may occur either in the sub- stance of the membrane — intrameningeal — or on its inner surface ; in the latter situation it may vary in extent from the size of a point merely to that of the hand. It is always of great importance to decide whether the htemorrhage is free on the surface (inter meningeaV)., or whether it is separated from the pia by a membrane (licematoma of the dura mater'). In the case of small haemorrhages as well as in that of newly formed vessels or of brown pigmentation, it is important to ascertain whether they are seated in the old tissue of the dura or in false membranes. The character of the surface often throws light on this question, for the surface which nor- mally is smooth and reflects light, often becomes uneven and dull when a morbid deposit is present ; but absolute certainty may be attained by scraping the surface with the edge of the knife, which readily removes any existent deposit. Apart from the presence of deposits, the inner surface may have lost that moist glistening appearance which normally belongs to it, if, for any reason (haemorrhage, hydrocephalus, tumor, abscess), the volume of the brain be increased and thus pressure be exerted on the dura and its inner surface rendered dry. In such a case, however, the surface always remains smooth. Increased moisture of the surface and, es- pecially, the presence of free fluid on the inner surface, are artificial conditions, and depend on cerebro-spinal fluid which has escaped from an injury of the pia. (5.) jSjjecial Morbid Conditions. Of the changes which are met with on the inner surface of the dura the most frequent and hence the most important are those which are due to — 56 DIAGNOSIS IN PATHOLOGICAL ANATOMY. 1. Inflammation. Purulent inflammation (^pachymenin- gitis interna purulenta'} is, as on the outer surface, rare and gives rise to much the same appearances. So, also, ossifying inflammation (pachymeningitis interna ossificans^, which re- sults in the formation of thin, irregular, and angular bits of bone on various parts of the dura, but particularly on the falx. That form of inflammation which is attended with fibrinous exudation, on the contrary, occurs only on the inner surface of the dnrs, (^pachymeningitis int. fibrinosa"). Such exudation may later become organized and converted into a fibrous false membrane (pachymeningitis int. fibrosa'). It is in this latter case that not only the above mentioned newly formed vessels are chiefly met with, but also haemorrhages (pachym. chronica int. hoemorrhagica, hcematoma') and pig- mentation (pachym. chronica int. pigmentosa), — the two lat- ter conditions being sequelae of and dependent on the former. It is a very simple matter to examine any of these conditions microscopically : it is only necessary to scrape off the fibrinous exudation or the false membrane, and spread it out under a covering glass with the addition of a drop of a solution of common salt. The membranes consist of cells and fibrous tissue in varying proportions, and the more abundant the cells are, the more recent is the membrane. The blood-vessels, which are often present in enormous numbers, are remarkable for their large caliber as contrasted with the extreme tenuity of their walls, which consist of little more than a layer of endothelium ; and thus, also, is explained their extreme lia- bility to rupture. If one of the brownish spots is examined under the microscope the discoloration is seen to depend on the presence of collections of reddish-brown or yellowish-red pigment which is generally amorphous, but may occur in the form of crystalline rhombic plates (hcematoidine) . Adhesive inflammation, which is so common in serous membranes, is rare in the dura, and when it does occur is usually of syphilitic origin — especially if the dura and pia be adherent over a large extent. I should not think it nec- essary to mention the fact that the membranes are, in their MEMBRANES OF THE BRAIN. 57 normal condition, necessarily connected together where the veins of the pia empty into the longitudinal sinus, if I had not learned by experience how liable beginners are to forget it. It is somewhat more difficult to distinguish between these vessels and inflammatory adhesions which, beginning at some little distance from and extending as far as the longitudinal sinus, sometimes unite the dura and pia ; though error may always be avoided by carefully observing the char- acter and distribution of the vessels in such adhesions. The inner resembles the outer surface also in the rarity with which it is the seat of tubercular inflammation ; when this does occur here, it is merely an extension of the process and never results in the formation of relatively large cheesy nodules ; should these be found, they may be regarded as in all probability the remains of gummata. These are often adherent to the pia, are associated with changes in the brain itself, and always set up at their periphery chronic pachy- meningitis (fibrinous, hsemorrhagic, etc.). 2. True neoplasms of various kinds are met with in the dura. Sarcomcu, generally the spindle-celled variety, occurs primarily in this situation, and may attain great size and perforate the bone (^fungus durce matris). Sometimes such a degree of inflammatory action accompanies the sarcomatous growth as to mask its characteristic nodules. Carcinoma^ on the contrary, is always secondary and either metastatic or an extension of a process which originated elsewhere. There is a peculiar kind of morbid growth which is sometimes found and is composed entirely of large flattened cells which may show a concentric arrangement ; this was formerly considered by all authorities to be epithelioma of the dura mater; but of late it has received the name of endothelioma^ and has been referred to a growth of the endothelial cells of the membrane. 6. THE PIA MATER OP THE CONVEXITY. The next step after the examination of the right half of the dura is to examine that of the corresponding half of the pia. 68 DIAGNOSIS IN PATHOLOGICAL ANATOMY.
Key Takeaways
- Carefully note adhesions between the bone and dura to avoid injury during examination.
- Use Griesinger's method for examining young children’s brains, as it causes less damage than traditional methods.
- Examine the inner surface of the skull and dura mater for signs of inflammation or neoplasms.
Practical Tips
- When examining a patient with suspected brain injury, prioritize careful handling to avoid further damage.
- Use Griesinger's method when dealing with young children to minimize trauma during diagnosis.
- Be aware that the presence of certain discolorations on the inner surface of the skull can indicate underlying conditions.
Warnings & Risks
- Avoid forcibly removing adhesions between bone and dura as it may cause further injury or complications.
- Do not confuse Pacchionian bodies with false membranes, as they are part of the pia mater.
- Be cautious when examining the longitudinal sinus to avoid damaging underlying structures.
Modern Application
While the techniques described in this chapter are rooted in historical practices, many of the principles and observations about brain injuries and diseases remain relevant today. Modern medical imaging has improved diagnostic accuracy but cannot replace a thorough physical examination. Understanding these historical methods can provide valuable context for interpreting clinical findings.
Frequently Asked Questions
Q: What is Griesinger's method, and why is it important?
Griesinger's method involves sawing through the bone and brain together to examine the brain in cases where the patient is a young child. This technique causes less damage than traditional methods because the brain of a young child is softer and more easily damaged.
Q: How can one identify signs of inflammation on the inner surface of the dura mater?
Signs of inflammation on the inner surface of the dura mater include brown discoloration, which may be diffuse or limited to smaller patches. These changes are often due to blood within or without the vessels and can indicate conditions such as purulent or ossifying inflammation.
Q: What should one do if they encounter adhesions between the bone and dura during examination?
If adhesions are encountered, it is important to carefully divide them rather than forcibly removing them. Forcible removal can cause further injury or complications. Carefully dissecting off the dura will help avoid damaging underlying structures.