An Atlas of Pathology of the Brain - E. Payne (SANDOZ, 1969) WW

63 Pages·1969·29.78 MB·English

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An Atlas of Pathology
of the Brain

E.E. Payne, M.D.
The Welsh National School of Medicine
Department of Pathology
Cardiff/ Wales

Published by SANDOZ
1969
Contents Page

Preface i
The Normal Brain 2
Hydrocephalus 8
Cerebral Oedema 12
Intracranial Space-Occupying Lesions and Cerebral Herniations 14
Intracranial Vascular Disease 16
Intracranial Neoplasms 30
Intracranial Infections 42
Demyelinating Diseases 48
Degenerative and Metabolic Diseases 50
Congenital Malformations 56

Index of Illustrations 61
Preface

This atlas has been designed to present the gross pathological
appearance of the brain in a number of disorders which affect
this organ. The illustrations have been selected to demon-
strate the common and a few of the less common pathological
conditions. The legends to the illustrations indicate the
general nature of the pathological process shown in each
specimen. A detailed explanatory text on each case has been
purposely omitted; it was felt that the written word would
distract the observer’s attention from the basic pathological
features which are self-evident in the illustrations.

The nervous system forms the central core of our actions,
reactions and responses and as such we are all concerned
to learn more about the disturbances which affect it. The
delicate mechanism of the brain may be upset by either
physiological disturbances, by disorders of the viscera or by
disease of the brain itself. On frequent occasions the medical
practitioner is cognizant that some temporary derangement
of cerebral function is present in his patient, but in many
cases he is unaware of the precise pathological process
that is being enacted within the nervous system. The com-

plexity of the anatomical connections, the physiological proc-
esses and the pathological disturbances of the central nervous
system make its study something of a speciality. Much detailed
research work will be necesssary before many of the common
pathological conditions are completely understood. In the
meantime this atlas will serve as a reminder of the pathological
appearance of the brain in a number of conditions. Most of
the disorders illustrated are commonly met in clinical and
pathological practice. The few uncommon or rare conditions
shown will be of interest to the physician, surgeon or pa-
thologist who specializes in the study of neurological dis-
orders.

Some of the illustrations are of fresh tissue while others are of
formalin fixed tissue. The colour of the large thin sections is
that seen by the pathologist when he examines a fixed spec-
imen; the sections have not been stained. The large thin
sections have been reproduced in this atlas at their natural
size, allowing the reader to make direct measurements of the
dimensions of the lesions.

The technique for the preparation of large thin sections of brain mounted on paper

The brain is fixed by suspending it from the basilar artery in
6000 ml of 4°/o formaldehyde in water. About one week later
the brain is examined and cut into slices in some convenient
plane; one slice, between 2 and 5 cm thick, is selected for
processing for large thin sections. The selected slice should
contain part of the main pathological lesion that is to be
studied. If necessary this slice can be placed in fresh fixative
for another 5-6 days to ensure complete fixation. When
convenient the slice is washed in running water for two days
to remove any unbound formalin. The washed slice is em-
bedded in warm 25°/o gelatin solution; the gelatin block
containing the specimen is affixed by gelatin to the specimen
plate of a modified “sledge” large section microtome. The
block and plate are placed in a deep-freeze overnight. The
specimen plate is bolted to the microtome, the upper surface
of the block is painted with warm 7° gelatin solution and
large sections of brain are cut at 500 microns thickness. The

sections, each separated by a piece of cellophane, are stored
in 4°/o formaldehyde solution.

When it is convenient to mount the sections they are washed
in running water for 3—4 hours. Each large thin section of
brain is then mounted between layers of cellophane and
backed with a layer of absorbent paper. The layers are built up
on a perspex plate and between each layer there is a thin film
of mounting solution (7°/o gelatin and 7°/o glycerol in equal
parts). Any air bubbles present are removed and the section
enveloped in cellophane on the perspex plate is allowed to
set for half an hour. The plate is hung in a drying cabinet at
27°C for about 18 hours and then the sections can be peeled
off the perspex plate.

Serial sections are labelled and can be examined at leisure.
The sections provide an accurate record for research pur-
poses and a useful aid in teaching.
The Normal Brain

The appearance of the brain alters between birth and the
senilium. In the newborn the brain is soft and grey in colour,
the differentiation between the grey and white matter is not
distinct. As myelination of nerve fibres proceeds the brain
takes on a firmer consistency and the white matter stands
out clearly. The main tracts in the brain acquire their myelin
by the end of the second year of life, thereafter the myelination
process proceeds more slowly. An intact myelin sheath
appears to be essential for the proper function of the nerve
fibres. The whole process of myelination is completed about
the end of the second decade of life wnen some of the associ-
ation tracts receive their myelin coat.

The brain is fully formed in the young adult and at that stage
the weight should be between 1250-1450 g. for the male and
1200-1400 g. for the female.

As middle age passes and senescence appears the brain
shows slight general reduction in its volume; this is thought
to be due to a diminution of its water content. A study of large
thin sections of the brain of various age groups shows that in
general the brain substance atrophies with increasing age.
While the consistency, colour and functional ability of the
normal brain alter during life, there is no change in the general
shape of the brain structures.

The gyral pattern on the external surface of the normal brain
shows a slight variation from one case to another. Marked
deviation from the normal size and shape of the cerebral
convolutions are occasionally seen as a feature of congenital
brain anomalies: the gyri may be exceptionally large and
smooth with few sulci (lissencephaly) or at the other extreme
the convolutional surfaces may be tracered with multiple
shallow sulci (micropolygyria).

There is very little space between the normal brain and the
inner surface of the cranium (Fig. 1). Some common neuro-
pathological conditions such as cerebral atrophy and cerebral
oedema are most evident when the brain is examined in situ
after removal of the skull-cap for it is only at this time that
a true comparison can be made between the size of the brain
and the capacity of the cranial cavity.

The membranes which cover the external surface of the
central nervous system help to protect and support the deli-
cate nervous tissues. The outermost membrane, the dura, is
thick, strong and pliable; it conceals the venous sinuses
between its fibrous lamelae at the points where the processes

2

of the membrane project into the skull cavity to form the
tentorium cerebellum and the falx cerebrum. The normal
arachnoid mater is a thin homogeneous transparent mem-
brane; slight thickening of this membrane is a common finding
in advanced life. The pia mater, also a thin membrane, is
adherent to the brain tissue; the pia with the arachnoid con-
stitute the leptomeninges which form the boundaries of the
cerebrospinal fluid space.

The brain receives its nutriments by way of the carotid and
vertrebral arteries; the interconnection of these vessels on the
basal surface of the brain forms the Circle of Willis.

Three main arteries (the anterior, middle and posterior cere-
bral arteries) leave the circle on each side and supply the
respective areas of brain tissue. At the peripheral part of
their distribution the arteries on each hemisphere form an
anastomotic network with each other, producing the so-called
“boundary zones” or “watershed areas”. The boundary zone
areas of brain tissue are particularly susceptible to haemor-
rhagic infarction in hypotensive states.

The cut surface of the brain reveals something of the complex
architecture of cerebral tissues. The over-folding of the corti-
cal ribbon produces the convolutions which tend to be
rounded in outline and are separated by narrow sulci. The
grey matter of the cortical ribbon and the basal ganglia stand
out clearly from the myelinated nerve fibres which constitute
the centrum ovale and capsular systems.

A sagittal section through the median plane of the brain
(Fig. 4) shows the septum pellucidum and parts of the ventri-
cular system. For most routine examinations, the brain is cut
in the coronal plane (Fig. 5): this plane of section provides
the observer with an adequate view of the basal ganglia,
ventricular system and the general characteristics of the
hemispheres. The cavities of the normal ventricular system
are little more than slit-like spaces; in the normal young adult
the corners of the ventricles are pointed and the ventricular
volume is of the order of 15 to 20 ml. As age advances, the
ventricular volume increases to compensate for the slowly
progressive reduction in the amount of brain tissue.
Transverse section of the brain (Fig. 7) cut through the level
of the basal ganglia clearly shows the relative positions of the
central masses of grey matter and the slight irregularity in the
size of the cerebral hemispheres, the dominant hemisphere
(commonly the left) being usually slightly larger than the right.
Fig. 1. Vertex of the brain in situ.

There is very little space between the normal brain and the cut edge
of the skull. When the dura mater is removed the brain sinks
downwards and consequently leaves a small space between the brain
and the frontal bones.

Fig. 2. The base of the brain.

The normal arachnoid membrane is transparent and as such does not
interfere with the view of the structures at the base of the brain.

This view of the brain allows for the examination of the cranial nerves,
the major blood vessels, the brain stem and the inferior surfaces of
the cerebrum and cerebellum.
Fig. 3. Lateral aspect of the brain.

The normal brain has rounded contours, the
gyri are wide and the sulci are narrow.

_. Fig. 4. Medial aspect of the brain.

Note that the posterior end of the septum
pellucidum tapers to a point (arrowed).
Fig. 5. Oblique coronal section.

The section passes through the red nuclei which are situated just
above the substantia nigra in the mid-brain.
Fig. 6. Sagittal section.

The large thin section of the brain is cut in the sagittal plane to one
side of the mid-line. The cerebral convolutions and cerebellum are
clearly shown. The head of the caudate nucleus is prominent. The _
thalamus and substantia nigra can be distinguished.
Fig. 7. Transverse section.

This cut is through the basal ganglia and the thalamus. The normal

ventricular system is seen to be little more than a slit in the brain
substance.

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