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Chapter 11
Nervous system diseases
Diseases of the nervous system present with a
rather bewildering combination of clinical
symptoms and signs. For a clinician to make
sense of these, it is necessary to have some
knowledge of the anatomy and of the
pathologies that may occur.
Clinical examination should help to identify the
anatomical site of the problem, and a
knowledge of the possible pathologies that may
occur should be a guide to the further
investigations, immediate treatment and further
management.
The major pathologies encountered are
Pathology of the arteries or veins which result
in cerebrovascular accidents (CVA’s or strokes)
Abnormalities in the circulation of the cerebro
spinal fluid (CSF)
Congenital anomalies
Neural tube defects
General diseases
Dementia: for example, Alzheimer’s disease
in adults and tuberous sclerosis in children
Parkinson’s disease
Multiple sclerosis
Infections
Tumours
Benign, malignant and metastatic
The pathological entities to be illustrated in this
chapter provide a basis for the practical
knowledge needed to interpret the clinical
findings in patients presenting with diseases of
the nervous system.
Normal anatomy
Before embarking on a discussion of the
pathology of the nervous system it is necessary
to know something about the normal anatomy
so as to be able to understand and interpret the
symptoms and signs of diseases of the nervous
system with which patients present.
Anatomical parts of the brain
1(a) and (b)
(a) These diagrams indicate the main gross
features of the brain as seen from above and
from the under surface of the brain.
The brain surface is folded (concertinered) so
that a large surface area can be packed into a
smaller space. These folds are called gyri.
The wavy black lines in the diagrams are spaces
between the gyri and they are called sulci.
Black arrows frontal lobe.
Blue arrows occipital lobe.
Green arrow temporal lobe.
Grey arrow parietal lobe.
Red arrow cerebellum.
Brown arrow pons.
Yellow arrow medulla (or medulla oblongata)
The anterior part of the medulla contains the
pyramids which carry the motor fibres from the
cortex to the spinal cord.
Orange arrow spinal cord.
Light blue arrow in the right hand diagram is
the central sulcus. The gyrus anterior to this
sulcus is the central gyrus and it contains the
motor neurons in its grey matter. It is
sometimes called the motor cortex.
Purple arrow indicates the two optic nerves and
the optic chiasm in which half the sensory
fibres from each eye cross to the other side of
the brain.
(b) This is a normal brain for comparison with
the diagram.
The black arrow indicates where some of the
leptomeninges have been stripped from the
surface of the brain. The cortex to the right of
the arrow has no leptomeninges, while to the
left the leptomeninges are intact.
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2(a) and (b)
(a) The right lateral view of the brain with the
same coloured arrows as before. The light blue
arrow indicates the lateral sulcus that marks the
superior extent of the temporal lobe.
When this sulcus is opened, the insula which
runs vertically in its base can be seen
The other coloured arrows are as in the
previous figures.
(b) This is a view of the right lateral surface of
the brain of an adult who had dementia caused
by Alzheimer’s disease.
The leptomeninges have been stripped off so
that the cortical surface can be seen more
clearly.
The brain is atrophied and smaller than normal.
The gyri are thinner than normal which makes
the distinction between gyri and sulci more
obvious.
Can you identify the various parts of the brain
from the diagram in 03?
3(a) and (b)
(a)
5 The left medial view of the brain. The arrows
are the same colours as before except for the
following:
The light blue arrow indicates the pituitary
gland.
The yellow arrow is the corpus callosum.
The grey arrow is the fornix.
The orange arrow is the choroid plexus.
(b) Left medial view of the brain shown in Fig
04.
Can you identify the various anatomical
features illustrated in the diagram, and can you
identify some other anatomical features not
mentioned in the diagram?
4(a) and (b)
(a) The cranial nerves are paired.
Red arrow. Cranial nerve I (olfactory nerve)
sense of smell. Its distal end is widened and this
is called the olfactory bulb.
Purple arrow cranial nerve II. (optic nerve)
sense of sight.
Yellow arrow cranial nerve III (oculomotor
nerve) Eye movements
Orange arrow cranial nerve IV. It is thin and is
the motor nerve to the superior oblique muscle
which moves the eye downwards and outwards.
Black arrow cranial nerve V. A big nerve that
arises from the middle of the pons and is
sensory to the face.
Nerves VI, VII and VIII arise from the lower
border of the pons.
Green arrow cranial nerve VI which is motor to
the lateral rectus muscle of the eye.
Light blue arrow the medial half of this nerve
bundle is cranial nerve VII (facial nerve) motor
to the face muscles.
Light blue arrow the lateral half of the nerve
bundle is cranial nerve VIII (auditory nerve)
sense of hearing.
Cranial nerves IX to XII arise from the
anterolateral surface of the brain stem.
Brown arrow cranial nerves IX, X and XI.
Grey arrow cranial nerve XII. (vagus nerve)
(b) In this image the under surface of the brain
is shown and the cranial nerves are arrowed.
The specimen is not perfect because the brain
was not removed as carefully as it should have
been. Hence not all the paired nerves can be
seen.
The nerves are labelled with the same coloured
arrows as in the diagram.
The orange arrow indicates where the IVth
nerve should be.
The white arrow indicates the base of the brain
from which the pituitary gland arises. It has
been left in the base of the skull in the pituitary
fossa when the brain was removed.
5 This is a view of the base of the skull from
which the brain has been removed. The stalk of
the pituitary gland is marked by a green arrow.
The pituitary is in a bony compartment called
the pituitary fossa. The blue arrows indicate the
internal carotid arteries.
The outer sides of the lateral walls of the
pituitary fossa are lined by layers of dura mater
3
in which pass the cavernous sinus, the carotid
artery and the cranial nerves, 111, 1V, V and
VI.
Pathology in the region of the pituitary fossa
causes pressure on one or more of these cranial
nerves and paralysis of one of these nerves is a
good sign of the site of such pathology.
Autonomic system
There are two components sympathetic and
parasympathetic.
They have complex connections throughout the
brain and spinal cord.
One component of the system that can be seen
naked eye and which has some clinical
associations is the sympathetic trunk.
This is a recognizable length of nerve fibers
that has ganglia (nodules of aggregated
neurons) placed at regular intervals along the
‘trunk.’
The sympathetic trunk runs along the
anterolateral aspect of the vertebral bodies for
the whole length of the spinal column from the
base of the skull to the coccyx.
6 Diagram of the sympathetic trunk.
Clinical aspects of the sympathetic trunk
The operation of lumbar sympathectomy is
done to improve the blood supply to arteries in
an ischaemic leg.
The operation consists in excision of a segment
of the sympathethic trunk (sometimes called the
sympathetic chain).
Cervical sympathectomy may be done for
similar reasons, and sometimes to relieve
intractable pain.
Destruction of the upper portion of the thoracic
section of the sympathetic trunk results in a
clinical syndrome called Horner’s syndrome.
By far the commonest cause of this is
infiltration by a lung cancer in the apical
segment of the right lung.
Examples of clinical signs that can be
correlated with the anatomy.
Cranial nerve palsies
7 This man has been asked to look to his right.
His right eye has not moved, which indicates
that he has a right lateral rectus muscle
paralysis.
This was due to a pituitary tumour expanding
his pituitary fossa and damaging his right VIth
nerve.
8(a), (b), (c)
(a) This woman has been asked to look to her
right while keeping her head still.
Her right eye has not moved, indicating that she
has paralysis of the right VIth nerve.
(b) She has been asked to put out her tongue.
It deviates slightly to the right, and the right
side is slightly atrophic as compared with the
left side.
She has a paralysis of her right XIIth nerve.
The only place where both of these nerves can
be damaged at the same time is where they
leave the brain stem between the lower border
of the pons where the right VIth nerve emerges,
and the lower part of the medulla where the
right XIIth nerve emerges from the brain stem.
In fact she had a tumour that arose from the
tissue covering the brain at this site. It was
removed surgically.
(c)
The blue line represents the VIth nerve arising
from the lower border of the pons and running
forwards through the cavernous sinus beside the
pituitary gland and through the posterior aspect
of the orbit and then innervates the lateral
rectus muscle of the eye.
The green line represents the XIIth nerve
emerging from the brain stem between the
pyramid and the olive, leaving the skull via the
foramen in the mastoid bone and passing
4
forward in the floor of the mouth to innervate
the tongue.
The red square represents the site of the tumour
that was surgically removed from this patient.
9 This boy has involvement of the middle
(maxillary) branch the right Vth nerve by
herpes zoster. The herpes zoster infection
involves a cranial nerve or a spinal nerve trunk
unilaterally. This case demonstrates the way in
which the Vth nerve supplies sensation to the
face. The Vth nerve has 3 branches ophthalmic, maxillary and mandibular.
It extends for a variable distance from the
midline (the vertebral column) in the back to
the midline anteriorly.
The rash demonstrates the distribution of a
nerve root which sweeps downwards and
around to the anterior abdominal wall.
12 Diagram of the surface markings of the
nerve roots
Horner’s syndrome
13(a) and (b)
(a)
10(a) and (b)
(a) This man has paralysis of the right V11th
nerve.
The right side of his forehead is not wrinkled.
His right eye will not close
and the right side of his face is drooping.
He was dribbling saliva from the right side of
his mouth.
This paralysis has been accentuated by asking
him to ‘show his teeth.’
The main causes of VIIth nerve palsy are CVA
(stroke), Bell’s palsy and traumatic damage to
the nerve.
Bell’s palsy is a sudden onset of unilateral
paralysis of the VIIth nerve.
Its cause is not known except that it may follow
a viral infection.
It may be transient or permanent.
(b) Operative dissection of the left VIIth nerve.
The branches of the nerve (black arrows) have
been displayed after the superficial lobe of the
parotid gland has been removed as treatment of
a pleomorphic adenoma of the parotid.
It is important to carefully preserve all the
branches of the nerve or else the patient will
have post operative partial paralysis of the
VIIth nerve.
(a) This 67 year old man has a Horner’s
syndrome.
He has ptosis of the right eyelid.
The right eye is smaller than the left one and it
is sunken into the orbit (enophthalmos)
The pupil of the eye is small and it does not
respond to light stimulus.
There is no sweating on the right side of his
face although there is profuse sweating on the
left side.
Note that he has the blue marks of the
radiotherapist over the left side of his upper
chest.
(b)
(b) Chest X-ray shows that he has an advanced
lung cancer involving the apical segment of his
right lung.
The tumour has invaded the upper portion of
the right thoracic sympathetic trunk.
Blood supply to the brain
I will begin with the arterial supply and
illustrate some of the pathology associated with
arteries. Then I will illustrate the normal venous
supply and the pathologies that affect the veins.
Arterial supply
11 This patient has herpes zoster of the right
first lumbar nerve root
The erythematous, vesicular rash involves one
nerve root unilaterally.
The brain has a double arterial supply.
Vertebral arteries:
5
One vertebral artery arises from each
subclavian artery in the base of the neck. They
pass through foramena in the lateral processes
of the cervical vertebrae and enter the skull
through the foramen magnum on the anterior
surface of the upper cervical cord and medulla.
At the inferior border of the pons they fuse to
form the basilar artery.
Internal carotid arteries:
A right and a left common carotid artery arise
from the arch of the aorta. In the upper neck
they divide into an internal and an external
branch.
The external supplies blood to the face and
neck, while the internal one enters the skull
through a foramen in the base of the skull. It
passes in the cavernous sinus and then forms
the main blood supply to circle of Willis.
The circle of Willis consists of the internal
carotid arteries, the middle cerebral arteries, the
anterior cerebral arteries and the posterior
communicating branch which connects with the
posterior cerebral artery.
14 This diagram illustrates the main arterial
supply to the brain.
Yellow arrow vertebral artery
Red arrow basilar artery
Brown arrow posterior cerebral artery
Grey arrow internal carotid artery with the
middle cerebral artery shown as a light blue
hatched line.
Light blue arrow anterior cerebral artery. The
two anterior cerebral arteries are connected by a
small anterior communicating artery.
The internal carotid arteries are connected to
the posterior cerebral arteries by posterior
communicating branches.
Black arrow superior cerebellar artery arising
from the distal end of the basilar artery.
Blue arrow anterior inferior cerebellar artery
arising from the proximal end of the basilar
artery.
Green arrow posterior inferior cerebellar artery
arising from the vertebral artery.
(a)
(b)
15(a) and (b) These diagrams give some idea of
the brain territories supplied by the three main
cerebral arteries.
Blue area middle cerebral artery
Brown area posterior cerebral artery
Green area anterior cerebral artery
16 This is a real dissection of the arteries that
form the circle of Willis at the base of the brain.
Brown arrows anterior cerebral arteries
Light blue arrow anterior communicating artery
Yellow arrow internal carotid arteries
Blue arrows middle cerebral arteries
Green arrows posterior communicating arteries
White arrows posterior cerebral arteries
Purple arrow superior cerebellar artery
Red arrow basilar artery
Grey arrow vertebral artery
I think that the easiest way to understand the
arterial and venous systems of the brain is to
see some of the effects of pathology in arteries
and veins. The pathology in veins will be dealt
with after the anatomy of the veins is
demonstrated.
Pathology in arteries
The underlying pathology in arteries is
atherosclerosis and hypertension.
Complications of these pathologies
Infarction caused by occlusion of arteries by
either thrombi or emboli.
Haemorrhage from rupture of their walls as a
result of hypertension.
The artery most often involved is the middle
cerebral artery.
Infarction
(a)
(b)
17(a) and (b)
(a) This middle aged patient died from a
‘stroke.’
The post mortem examination of the brain
indicated that there had been an infarction of
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the brain tissue in the distribution of the right
middle cerebral artery.
The brain tissue involved felt abnormally soft.
In (a) both middle cerebral arteries are exposed.
In (b) it can be seen that the right middle
cerebral artery (black arrow) is filled with
thrombus because it is a solid blue colour which
is different from the colour of the left artery.
The posterior communicating artery also
appears to be thrombosed (blue arrow) and
there is haemorrhagic infarction of the cerebral
peduncles.
This would indicate that the thrombotic
occlusion was at the bifurcation of the right
internal carotid artery.
Can you also see a small unruptured aneurysm
on the anterior communicating artery?
Small branches from the middle cerebral artery
supply blood
to the internal capsule on the deep aspect of
the artery
to the posterior part of the frontal lobe on the
upper part of the artery and
to the temporal lobe on the lower part of the
artery.
(a)
(b)
18(a) and (b) In this specimen a deeper
dissection of the middle cerebral artery has
been made.
Its distribution can now be seen more clearly.
Below the artery there is haemorrhagic
infarction in the temporal lobe and internal
capsule. (blue arrow)
above it there is haemorrhagic infarction of the
most posterior portion of the frontal lobe. (red
arrow)
(a)
(b)
19(a) and (b) View of the under surface of the
brain of a 65 year old male who had a ‘stroke’ 6
years before he died.
During this time he suffered a severe loss of
memory.
The peculiar aspect of this memory loss was
that he remembered events until age about the
age of 30 years. Memory stopped at this time.
The infarcted tissue has been absorbed and
there are spaces in the distribution of the right
middle cerebral artery.
Red arrow infarction of the anterior end of the
temporal lobe and the posterior end of the
frontal lobe.
Blue arrow an area of infarction of the
inferomedial part of the temporal lobe.
This area includes the hippocampus, and
infarction of this would have been responsible
for the severe memory loss.
20 This brain shows the presence of infarction
of both occipital lobes as a result of occlusion
of both posterior cerebral arteries.
The edges of the infarcted brain tissue can be
seen as the haemorrhagic areas beneath the
surface of the brain.
21 This brain shows the appearances of a recent
infarction caused by thrombosis of the left
middle cerebral artery.
The left hemisphere is much larger than the
right.
This is due to oedema in the white matter in the
left hemisphere.
There is always a great deal of oedema
associated with such an acute infarction.
Resolution of the oedema occurs in the post
infarction recovery stage, and this accounts for
the restoration of varying amounts of brain
function.
An acute cerebral infarction (CVA) affecting
one hemisphere causes a sudden onset of
paralysis of the whole side of the body on the
opposite side to the infarction, and loss of
consciousness.
Some generalizations:
When the CVA is caused by a thrombosis, the
paralysis appears a little more slowly than if it
was caused by a haemorrhage.
When the CVA is caused by a haemorrhage the
paralysis and unconsciousness appear very
quickly.
7
Recovery is more likely from a thrombotic
infarction than from a haemorrhage because
there is less loss of cerebral cortical tissue.
22 This brain shows haemorrhage into the
internal capsule and adjacent brain tissue of the
right hemisphere.
This may have been the primary pathology, but
following a thrombotic infarction the brain
tissue is softened and secondary haemorrhage
often occurs and results in death.
On clinical grounds alone it is not always
possible to identify the exact site of a
haemorrhage, but modern imaging makes this
possible.
With the introduction of highly sensitive
imaging techniques in the late 20th century,
patients who have had an acute CVA have
imaging investigations as soon as possible after
the acute episode to ascertain whether the CVA
has been caused by a thrombotic episode or by
a haemorrhage.
The results of this imaging determine the
immediate treatment and make it possible for
effective treatment to be instituted. As a result,
the survival after a CVA has been greatly
improved.
Ancillary treatment of CVA’s such as
Occupational therapy, Physiotherapy and
Speech therapy have also contributed to the
revolution in the treatment of ‘strokes.’
23 This is a brain from a patient who had a
thrombotic infarction in the region of the right
internal capsule a number of years before death.
He died from another cause.
The infarcted tissue has been resorbed and a
cavitated area is left. (red arrow)
In passing, the black arrow indicates the insula
which is also supplied by the middle cerebral
artery.
Haemorrhage
24 Haemorrhage into the cerebellum.
Longitudinal section view.
25 Haemorrhage into the cerebellum in another
patient. Transverse view.
Subarachnoid haemorrhage
This is defined as the presence of blood in the
subarachnoid space which is the space between
the two layers of the leptomeninges, the soft
tissue coverings of the whole surface of the
brain and spinal cord.
One thin layer of leptomeninges is adherent to
the surface of the brain and spinal cord. This is
called the pia mater. There is a filmy lattice
work layer between this and the outer layer
which is called the arachnoid mater.
This space is called the subarachnoid space.
CSF circulates in this space.
The brain and spinal cord are covered by a
further layer of dense fibrous tissue called the
dura mater.
Subarachnoid haemorrhage occurs from rupture
of cerebral aneurysms or arterio-venous
malformations.
26(a) and (b)
(a) is a segment of spinal cord in which the dura
mater has been opened with a vertical cut.
Subarachnoid haemorrhage can just be seen.
(b) the dura mater has been removed to reveal
the haemorrhage in the subarachnoid space.
The presence of blood in the subarachnoid
space can be demonstrated by the technique of
lumbar puncture in which a fine needle is
inserted through the dura mater in the lower
lumbar region into the subarachnoid space and
the CSF is sampled through this needle.
27 In this specimen the arteries forming the
posterior part of the circle of Willis have been
dissected.
Yellow arrows carotid arteries
Green arrows posterior communicating arteries
White arrows posterior cerebral arteries
Blur arrows middle cerebral arteries
Red arrow shows an unruptured cerebral
aneurysm (sometimes called a ‘berry’
aneurysm.
28 In this specimen the arteries at the base of
the brain have been dissected. There is an
8
unruptured aneurysm on the right middle
cerebral artery (black arrow) and a ruptured
aneurysm on the right anterior cerebral artery
(red arrow), with haemorrhage into the brain
tissue and subarachnoid space
29 This specimen shows a ruptured aneurysm
(red arrow) on the left vertebral artery with
haemorrhage into the subarachnoid space.
30(a) and (b)
(a) and (b) This specimen shows the presence
of an arteriovenous malformation in the
leptomeninges covering the lower lumbar
portion of the spinal cord.
It ruptured causing subarachnoid haemorrhage
that resulted in death from the effects of raised
intra cranial pressure.
These malformations may occur in the
leptomeninges anywhere in the central nervous
system.
They are usually amenable to surgical excision
with recovery.
Subdural haemorrhage (haematomas)
Bleeding into the subdural space results from
traumatic rupture of veins.
The bleeding proceeds slowly and results in
symptoms arising days after the original injury
which may be so trivial as not to have been
noticed by the patient.
The symptoms are increasing drowsiness with
unconsciousness from the result of raised intra
cranial pressure.
Once a diagnosis has been made surgical
treatment is effective.
(a)
(b)
31(a) and (b) are the front and back views of a
brain specimen that shows the presence of
accumulated blood beneath the dura mater over
the right hemisphere.(blue arrow)
The underlying brain is compressed from the
pressure and the right hemisphere is deviated to
the left.
The subdural haematoma must have gone
undetected during life.
When there is raised pressure within the skull
as in this case, the brain stem is pushed down
into the foramen magnum which is the only
outlet for the relief of the pressure.
This is called cerebellar ‘coning’ and is the
cause of death.
Extra dural haemorrhage
This occurs as a result of rupture of the
superficial temporal artery.
This small artery runs vertically just anterior to
the ear along the surface of the dura lining the
inner surface of the skull.
32 Diagram to show the surface marking of the
superficial temporal artery.
Trauma to the side of the head in this ‘temple’
region may cause a fracture of the skull with
rupture of this artery.
Such an injury has a fairly typical history.
There is an injury either during football or from
a hit by a cricket ball.
The person falls to the ground and is
unconscious for a short time.
He then recovers and continues with the game.
Some time later he becomes drowsy and then
unconscious.
He will die from the effects of raised intra
cranial pressure unless a craniotomy (a hole in
the skull bone that allows access to the dura and
the brain) is performed to let the blood out.
The bleeding from the artery can be stopped at
the time of the craniotomy.
Venous supply of the brain
The cerebral veins drain blood from the brain
and it is then returned to the heart via the
internal jugular veins.
i33(a) and (b)
(a) Diagram of the cortical surface of the brain
showing the main cerebral veins.
Red arrow superior sagittal sinus.
Green arrow middle cerebral vein
Light blue arrow transverse sinus
9
Light green arrow sigmoid sinus
Black arrow internal jugular vein
(b)
(b) Diagram of the medial surface of the brain
to show the venous drainage.
Red arrow superior sagittal sinus which runs in
a tube produced by folds of the dura mater. This
fold forms the superior margin of the falx
cerebri, the dura mater that separates the two
cerebral hemispheres.
Blue arrow inferior sagittal sinus which runs in
the folds of dura mater along the inferior border
of the falx cerebri.
Black arrow anterior cerebral vein
Green arrow internal cerebral vein that drains
blood from the deep parts of the brain, and
anteriorly from the cavernous sinus. The latter
drains blood from the orbit.
Yellow arrow great cerebral vein which drains
blood from most of the deep parts of the brain.
Light blue arrow straight sinus which drains
into the sigmoid sinus and then into the internal
jugular vein.
Practical application of the anatomy of the
cerebral venous system.
(b) The thrombus is more clearly demonstrated
in this specimen in which more dura mater has
been included.
Thrombosis of deep cerebral veins
(a)
(b)
35(a) and (b) This brain came from a male 16
who had a cyanotic congenital heart
abnormality before the advent of effective
surgery for these anomalies.
The green arrow shows thrombosis of the
superior sagittal sinus and other surface veins
that drain into it.
Yellow and red arrows also show thrombosed
cortical veins and associated infarction of
underlying brain.
Patients with cyanotic congenital heart
conditions develop polycythemia which makes
the blood susceptible to coagulation (clotting).
CNS symptoms in such a patient are a signal
that venous thrombosis has probably occurred.
Thrombosis of the sagittal sinus
36 This brain came from a male 5 who
developed thrombosis of the deep cerebral
veins as a result of severe diarrhoea that led to
severe dehydration.
Cerebral vein thrombosis is a well recognized
complication of severe dehydration.
34(a) and (b)
Thrombosis of the cavernous sinus.
(a) A female 23 developed a rare post partum
complication – disseminated intravascular
coagulation.
One of the vessels that became thrombosed was
the superior sagittal sinus.
This resulted in death.
The red arrow indicates the thrombus in the
sagittal sinus.
The green arrow shows where thrombosis has
extended from the sagittal sinus into the veins
that drain the surface of the brain.
37 This brain shows thrombosis of the
cavernous sinus.
There is haemorrhage and infarction in the
adjacent brain whose veins drain into the
cavernous sinus.
This resulted from untreated acute infection of
the right orbit.
Thrombosis of the sagittal sinus
Thrombosis of deep cerebral veins
Thrombosis of the cavernous sinus
(b)
Orbital cellulitis - one cause of cavernous sinus
thrombosis.
38 This child has acute infection of the tissue in
the right orbit.
10
Such infection is usually caused by a
staphyloccus infecting the skin near the eye.
The orbital veins drain posteriorly directly
through the orbital foramen into the cavernous
sinus.
If the infection drains in this direction, the
cavernous sinus becomes thrombosed.
If the infection is not controlled by appropriate
antibiotic treatment, death may occur.
A result of cavernous sinus thrombosis from
another cause.
39 This patient had a sudden protrusion of her
right eye.
It was due to congestion of the orbital veins
caused by a thrombosis in the right cavernous
sinus.
The thrombosis resulted from severe
dehydration.
Congenital abnormalities that result in
obstruction to the flow of CSF
Acquired obstruction e.g. by infection or
tumour.
Constituents of the CSF
Cells - occasional mononuclear cells are present
but there are no red blood cells or neutrophils.
Glucose - 2.8-4.4 mmol/L
Protein - 0.15-0.45 g/L
When CSF is obtained at lumbar puncture as
part of the ‘workup’ in the diagnosis of a
suspected neurological disease, tests are made
to assess the levels of these constituents.
If meningitis is suspected, microbiological
cultures of the CSF are done as well.
An example of hydrocephalus caused by
obstruction of the foramena in the roof of the
4th ventricle.
Cerebro spinal fluid (CSF).
(a)
CSF is formed from the choroid plexus which
consists of vascular membranes that protrude
into the lateral, third and fourth ventricles.
It is a clear, colourless fluid that circulates
through the ventricles, into the central canal of
the spinal cord and out through two outlets in
the roof of the fourth ventricle into the
subarachnoid space that covers the whole of the
brain and spinal cord.
CSF acts as a protective buffer against trauma
to the nervous system.
It circulates into the venous system by passing
through projections into the superior sagittal
sinus called arachnoid granulations.
If there is a blockage at any point along the
pathway of this circulation, CSF accumulates
proximal to the obstruction and the ventricles
dilate.
This condition is called hydrocephalus.
Hydrocephalus results in raised intracerebral
pressure which is recognized by the presence of
headache, vomiting and papilloedema
(observed by ophthalmoscopic examination of
the retina).
Causes of hydrocephalus
(b)
(c)
40(a), (b), (c) This brain shows the presence of
fibrosis in the leptomeninges in the roof of the
fourth ventricle.
This resulted from meningitis.
Red arrow fibrosed (thickened) meninges.
Black arrow dilated fourth ventricle
Green arrow dilated superior part of the lateral
ventricle.
Yellow arrow dilated temporal part of the
lateral ventricle.
Further anatomy of the brain and spinal cord
41(a) and (b)
(a) Diagram of a slice through the middle
portion of the brain.
Black arrow corpus callosum (anterior end or
genu)
Light blue arrow at the top of the brain - grey
matter of the cerebral cortex. The inferior
11
extent of the grey matter is marked by the
dotted blue line.
W white matter
Blue arrow head of caudate nucleus
Red arrow thalamus
Green arrow basal ganglia and lentiform
nucleus
Brown arrow internal capsule
Orange arrow insula
Grey arrow third ventricle
Purple arrow hippocampus
(b) Slice through the middle portion of a brain.
The various anatomical features are marked
with different coloured arrows from those in the
previous diagram.
Red arrow the caudate nucleus with the
superior cerebral vein at the tip of the arrow.
Blue arrow inferior cerebral vein
Both of these veins drain blood from the deep
parts of the brain.
Orange arrow internal capsule
Dark green arrow basal ganglia
Light green arrow lentiform nucleus
Light blue arrow insula
Black arrow thalamus
Grey arrow corpus callosum
Yellow arrows mamillary bodies.
Portions of the ventricular system can be seen.
The lateral ventricles can be seen opening by a
small foramen (foramen of Munro) into the
anterior end of the third ventricle.
Applied anatomy of the fibre tracts of the CNS
The axonal fibres of the motor neurons carry
impulses from the cortex to all parts of the body
via the internal capsule, midbrain, pons,
medulla and spinal cord.
The sensory fibres carry impulses from all parts
of the body to the cortex via the same pathway.
The cerebellum is connected to this pathway
via three fibre tracts – the superior, middle and
inferior cerebellar tracts.
All of these fibres occupy a precise position
along these pathways.
Pathways of fibre tracts in the CNS below the
internal capsule.
42(a), (b), (c)
(a) shows slices of the brain as marked.
Purple arrow tectum of the midbrain which
includes the anterior and posterior colliculi.
One pair of colliculi can be seen adjacent to the
purple arrow.
Blue arrow the cerebral aqueduct through
which the CSF flows from the third ventricle to
the fourth ventricle.
Red arrow cerebral peduncle.
Yellow arrow the fourth ventricle in the middle
of the pons. The transverse fibres of the pons
can be seen.
Blue arrow pyramids in the medulla.
They are the cortico spinal tracts that carry
motor signals from the cortical neurons to the
neurons of the anterior horns of the spinal cord.
Green arrow dentate nucleus of the cerebellum.
The white matter and the cortical grey matter of
the cerebellum can be seen.
The cerebellum is responsible for the control of
balance.
(b) part of the lumbar portion of the spinal
cord.)
Red arrow spinal cord
Blue arrow dura mater that covers the spinal
cord
Green arrow transverse process of a vertebral
body.
The vertebral bodies are attached to each other
by fibrous ligaments that allow movement of
the spine.
Yellow arrow spinal nerve passing through an
intervertebral foramen.
(c) At the level of lumbar vertebra 4, the spinal
cord ends and becomes a mass of large nerves
that supply the lower abdomen and lower limbs.
This is called the cauda equina.
Note the filum terminale and cauda equina in
Fig.
43 Slice of the brain from a young adult with
acute leukaemia who died from multiple
12
cerebral haemorrhages caused by a deficiency
of platelets in the blood.
One of these haemorrhages can be seen in the
temporal lobe on the left.
Green arrow opening of the cerebral aqueduct
from the third to the fourth ventricle.
(d) and (e) (x2) and (x10) views of the Xth
(vagus) nerve nucleus (green arrow)
There are 3 cerebellar peduncles.
Superior which connects the cerebellum with
the cortex,
Middle which connects the two lobes of the
cerebellum
Inferior which is formed by the anterior and
posterior cerebellar tracts from the spinal cord
before they connect to the cerebellum.
(f) and (g) (x2) and (x10) views of the XIIth
nerve nucleus (black arrow)
(f)
(g)
(h)
(i)
(h) and (i)(x2) and (x10) views of the nucleus
of the spinal tract of Vth nerve (yellow arrow)
Red arrows the superior cerebellar peduncles
(j)
Anatomy of the medulla
(k)
44(a) to (n)
(a) Microscopic section (x1) through the upper
part of the medulla just below the pons.
(j) and (k) (x2) and (x10) views of the medial
lemniscus (pink arrow)
(l)
Purple arrow floor of fourth ventricle
Red arrow inferior cerebellar peduncle
Brown arrow pyramid
Orange arrow olive
Yellow arrow nucleus of the spinal tract of Vth
cranial nerve
Blue arrow nucleus of VIIIth nerve
Green arrow nuclei of IX and X nerves
Black arrow nucleus of XIIth nerve
Pink arrow medial lemniscus, the sensory fibres
from the spinal cord
(m)
(l) and (m) (x2) and (x10) views of the olive
(orange arrow)
(n)
(n) (x2) pyramid (brown arrow)
(b)
The anatomical distribution of the fibres can be
seen in pathological conditions that cause
destruction to the tracts. Some of these will be
demonstrated.
(c)
The cortico spinal tracts
(b)and (c) (x2) and (x10) views of the VIIIth
nerve nucleus (blue arrow)
45(a), (b), (c)
(d)
(e)
(a)This brain shows the presence of an old,
healed infarcted area in the insula and superior
surface of the left temporal lobe.
This was caused by a thrombus in the left
middle cerebral artery.
13
The infarcted area is cystic and there is a gliotic
reaction in the region from which the infarcted
tissue was resorbed.
45(b) and (c)
(b) This slice through the midbrain shows the
effect of the old infarction by loss of tissue in
the left cerebral peduncle.
This is due to loss of fibres in the corticospinal
tract (motor fibres).
(c) shows atrophy of the right pyramid in the
midbrain.
At this level the cortico spinal tract fibres are
beginning to cross in the decussation of the
pyramids.
Vertebro basilar insufficiency
Infarction in the medulla from thrombotic
occlusion of the vertebral, basilar and posterior
inferior cerebellar arteries
This lesion gives rise to the combination of
clinical signs known as the ‘lateral medullary
syndrome.’
A feature of vertebro basilar insufficiency is
that the symptoms appear suddenly and then
improve, and then appear again over a period of
months with a final episode of fatal
haemorrhage or thrombosis.
The clinical features are often used as an
exercise in correlation between symptoms, and
the anatomical structures that are affected.
Symptoms include
Vertigo and deafness (VIIIth nerve)
Hiccough and or vomiting (Xth nerve)
Dysphagia (IXth nerve)
Paralysis of the palate (XIIth) nerve
Cerebellar signs of ataxia (inferior cerebellar
peduncle.)
Facial pain and loss of sensation (spinal tract of
Vth nerve)
Anterior and inferior surface of the cerebellum
and medulla.
The right vertebral artery (blue arrow) and the
basilar artery (red arrow) are occluded by
thrombus as shown by their blue colour as
opposed to the appearance of the left cerebral
artery.
Green arrows indicate softening and necrosis of
the cerebellum in the territory supplied by the
posterior inferior cerebellar arteries.
(b)
(b) A x1 view of a section taken from the
midbrain of another patient who had a similar
vertebro basilar artery thrombosis.
The red arrow indicates the area of infarction in
the midbrain.
Compare this with Fig. and note the nuclei and
fibre tracts affected.
(c)
(c) A x2 view to show the loss of myelin and
neurons in the area of infarction.
(d)
(e)
(d) and (e) x2 and x20 views of the normal
choroid plexus within the fourth ventricle in
this specimen.
The choroid plexus is a papillary structure lined
by a single layer of small cuboidal cells that
cover a highly vascular core
It is found in all the ventricles in the brain and
secretes the CSF.
Spinal cord
Anatomy
Some pathologies
45(a) to (e)
Anatomy
(a)
47(a), to (f)
14
(a)
(a) A x1 view of a transverse section of the
upper cervical spinal cord just at the lower end
of the medulla.
The pyramids (brown arrow) have not yet
decussated (crossed), but the decussation of the
sensory fibres to form the medial lemniscus can
be seen. (red arrows)
(b)
Green tract carries the sensory stimulation for
pain and temperature to the cortex.
Yellow tract carries the stimulation for fine
touch to the cortex.
The 2 posterior columns of the spinal cord are
each divided into 2 fibre tracts – the fasciculus
cuneatus (C), and the fasciculus gracilis (G).
The posterior columns transmit sensory fibres
to the cortex and they control joint position
sense and vibration sense.
(b) Diagram of a transverse section of cervical
spinal cord to show the disposition of the major
tracts of nerve fibres that carry information
from the brain to the periphery, and from the
periphery to the brain.
(c)
P posterior horn of spinal cord
Sensory fibres from the posterior nerve root
pass through the posterior horn en route to the
ascending sensory tracts in the posterior
columns of the spinal cord.
Red arrow the anterior spinal artery.
This is a well formed artery and it supplies the
anterior two thirds of the spinal cord.
The posterior one third is supplied by a
number of small arteries.
All of the arteries to the spinal cord are fed by
branches of segmental arteries along the whole
length of the cord.
A anterior horn of spinal cord
Motor neurons (lower motor neuron cells) are
present in the anterior horn.
Motor impulses from the neurons in the
anterior horn pass via the anterior nerve roots to
innervate the muscles of the body.
(c) A x1 view of a transverse section of cervical
spinal cord stained to show the myelin that
surrounds the nerve fibres.
Blue arrows anterior spinal nerve roots.
Black arrow posterior spinal nerve root.
(d)
Blue tract is the crossed pyramidal tract or
cortico spinal tract.
It carries motor fibres that are derived from
the cortical motor neurons (upper motor
neurons) on the other side of the body and they
have crossed at the decussation of the pyramids
at the lower end of the medulla.
Black tract is the uncrossed pyramidal tract or
cortico spinal tract.
It carries motor fibres that did not cross to the
opposite side from which they derived.
(d) A x1 view of a transverse section of the
lumbar spinal cord stained with a myelin stain.
It shows the configuration of the fibre tracts at
this level of the spinal cord.
(e) and (f) An H&E x2 and x10 showing the
motor neurons of the anterior horn.
Pathologies that affect the spinal cord
Atrophy of the posterior columns
Infarction of the cord
Purple tract is the anterior spino cerebellar tract
Atrophy of the posterior columns
Red tract is the posterior spino cerebellar tract
48 A x1 view of a transverse section of the
lumbar spinal cord from a patient who had
15
atrophy of the posterior columns of the spinal
cord as a result of longstanding vitamin B12
deficiency.
This abnormality also occurs in alcoholics with
vitamin B12 deficiency, and in tertiary syphilis.
Patients with posterior column atrophy walk
with their feet spread apart so they walk on a
wide base to compensate from the cerebellar,
and they have a high stepping gait and stamp
their feet down after each step
These ‘trick’ movements compensate for the
loss of joint position sense and impairment of
balance.
50 This newborn baby has a
meningomyelocoele at the base of the spine.
It consisted of membranes that normally cover
the spinal cord extending through a defect in
the posterior laminae of the lower lumbar
vertebrae.
The membranes were transparent and there was
no neural tissue included in the herniation.
This is the least dangerous form of this neural
tube defect which is usually accompanied by
herniation of neural tissue with paralysis of
both legs, and faecal and urinary incontinence.
Other congenital defects may also be present.
Infarction
51 Meningomyelocoele in the upper cervical
region.
The lumbar region is the most common site for
a meningomyelocoele to occur, but it can occur
anywhere along the length of the vertebral
column.
Thrombosis of the anterior spinal artery may
result from atherosclerosis or from traumatic
rupture.
Thrombosis of the anterior spinal artery results
in infarction of the anterior two thirds of the
spinal cord with clinically detectable signs of
damage to the various fibre tracts involved.
49 Spinal cord infarction resulting from damage
to the the anterior spinal artery resulting from a
traffic accident.
Congenital conditions of the CNS
Only one of the very many congenital
conditions of the CNS will be considered.
Neural tube defects.
Meningo myelocoele
As part of a normal surveillance during
pregnancy, mothers nowadays have tests
performed at 12 weeks gestation for the
presence of congenital abnormalities.
The best known of these abnormalities is neural
tube defect.
An ultrasound of the uterus is performed.
This allows visualization of any abnormality
A small sample of amniotic fluid is aspirated
and tested for the presence of apha foeto
protein.
This is increased when a neural tube defect is
present.
Meningomyelocoeles are frequently
accompanied by hydrocephalus caused by what
is called an Arnold Chiari malformation.
In this defect, the cerebellar tonsils herniate
through the foramen magnum.
This is accompanied by elongation of the
medulla, and all of this tissue in the foramen
magnum results in obstruction to the flow of
CSF.
52(a) - (d)
(a) Brain stem showing the Arnold Chiari
malformation.
Yellow arrow midbrain
Blur arrow cerebellum
Green arrow base of the skull
Red arrows mark the level of the foramen
magnum
Next to the left red arrow the herniation of the
tonsils of the cerebellum into the foramen
magnum can be seen.
Next to the right red arrow the medulla can be
seen to be elongated so that it is extending well
below the foramen magnum.
As a result, the outlet of the 4th ventricle is
occluded and this has caused hydrocephalus.
(b)
16
(b) A longitudinal section of lumbar and sacral
spine from a child who died from infection of a
meningomyelocoele.
The defect in the posterior laminae of the spinal
column is shown by the red arrows.
Green arrows indicate the terminal portion of
the spinal cord as it entered the
meningomyelocoele.
It is characterized by the onset of mental
deterioration, restlessness, loss of memory and
incontinence progressing to total dementia.
(c) and (d)
The cause is not known.
(c) In some patients with Arnold Chiari
malformation, the spinal cord is split into two
parts, a condition called diastematomyelia (red
arrow)
Death usually results from intercurrent
infection.
(d) As well, the central canal of the spinal cord
which is not normally visible grossly, becomes
dilated, a condition called hydromyelia.
Anencephaly
Anencephaly is another congenital abnormality
that results from a defect in the development of
the neural tube.
It is easily visible in an ultrasound at 12 weeks
gestation.
(a)
(b)
53(a) and (b) Anencephaly The baby develops
with no brain tissue being formed.
General diseases
Dementia – examples
In adults
Alzheimer’s disease
Huntington’s disease
In children
Tuberose sclerosis
Dementia in adults
Alzheimer’s disease
This is a common form of dementia that affects
both males and females after 60 years of age
with about equal prevalence.
The progression of symptoms is variable,
sometimes being slowly progressive over many
years and sometimes being more rapid within a
few years only.
Pathologically the brain is smaller than normal
because of loss of grey matter.
The gyri are atrophic and the sulci are wider
than normal.
Microscopically the atrophy is confirmed and
the loss of cortical neurons can be seen.
Throughout the white matter there are scattered
accumulations of degenerate astrocytes that
form ‘plaques’ that can be best seen in silver
stained sections of brain tissue.
Changes in the organelles within nerve cells
show as a ‘ neurofibrillary change.’
Small depostis of amyloid are found throughout
the brain and in the walls of small blood
vessels.
54(a) to (f)
(a) This brain is smaller than that the one in (b).
The patients were of comparable age and
stature.
Patient (a) had Alzheimer’s disease.
Patient (b) was normal mentally.
(c)
(c) This is a slice of brain from a patient who
died from Alzheimer’s disease.
The gyri are atrophic and the sulci are widened.
There is dilatation of the lateral and third
ventricles (hydrocephalus) that has resulted
from the loss of brain substance.
(d) silver stain x10
17
(e) silver stain x20
(f) silver stain x20
(d) to (f) Microscopic section of a brain from a
patient with Alzheimer’s disease. (d) and (e)
show plaques and (f) shows neurofibrillary
change.
These are the characteristic microscopic
appearances seen in Alzheimer’s disease.
As well as this, the small blood vessels usually
have amyloid in their walls and deposits of
amyloid are scattered throughout the brain.
Huntington’s disease (chorea)
This is a form of dementia that begins in middle
life about 50 years of age.
It presents with gradually progressing mental
deterioration which is associated with
uncontrollable movements. - chorea)
Life expectancy after the onset of symptoms is
about 15 years.
It runs in families and is transmitted as an
autosomal dominant trait. The abnormality has
been localised to chromosome 6.
Pathologically the brain is atrophic and there is
particularly marked atrophy of the basal ganglia
with hydrocephalus that follows from the loss
of cerebral tissue.
55 Brain from a patient who died from
Huntington’s disease.
It is atrophic, there is dilatation of lateral
ventricles (hydrocephalus) and the basal
ganglia are atrophic. (red arrows)
Dementia in children
There are many causes
infections such as measles
storage diseases, in which
mucopolysaccharides are stored in the neurons
hormonal diseases such as cretinism and
chromosomal diseases such as mongolism.
The disease chosen to represent this group of
dementias is tuberous sclerosis.
This is a familial disorder in which the patient
is demented from childhood.
It is associated with
epilepsy
sebaceous adenomas on the face
linear areas of depigmentation on the skin
multiple angio leiomyomas in the kidneys and
rhabdomyomas in the heart.
Examination of the brain at post mortem shows
the presence of hard, white areas throughout the
brain cortex.
Microscopically these consist of areas of
proliferation of abnormal glial cells.
56(a), (b, (c)
(a)
(b)
(a) and (b) Brain from a male 16 who had been
mentally defective since birth and suffered from
epilepsy.
Clinically he demonstrated the features of
tuberous sclerosis.
The brain contained a number of hard creamy
areas in the cortex. (blue arrows)
On microscopic examination these areas
consisted of focal areas of proliferation of
abnormal glial cells.
These cells look just like the astrocytes of a
high grade astrocytoma, but the ‘tumours’ or
‘tubers’ increase in size only very slowly and
do not behave in a malignant fashion.
(c)
(c) Child with tuberous sclerosis.
He has a linear area of depigmentation (red
arrow) called a cafe au lait spot.
He also has some of the skin nodules – the
‘sebaceous adenomas’ that occur in this
condition.
The term sebaceous adenoma is a misnomer
because microscopically these lesions are
angiofibromas.
Children with dementia from the various
storage diseases such as Hurler’s syndrome also
develop large, firm brains.
18
General diseases
Parkinson’s disease
Multiple sclerosis
Parkinson’s disease is a sporadic disease that
affects males and females after about the age of
60 years.
It is associated with a depletion in dopamine in
the caudate nucleus, basal ganglia and the
substantia nigra.
Pathologically it is associated with destruction
of neurons.
In the cerebral peduncles one sees loss of
dopamine secreting pigmented cells in the
substantia nigra which can be seen grossly.
Clinically the patients have
tremor (particularly of the hands) at rest. This is
made worse by exercise and emotion.
their limbs become rigid
speaking becomes difficult and the voice is soft
balance is impaired
they walk with small steps and leaning forward
to maintain balance
they lose facial movements and the face has a
wrinkleless mask like appearance.
The disease is slowly progressive.
57 (a) and (b)
Two slices from the midbrain
(a) normal with normal colour of the substantia
nigra (red arrows)
(b) is from a patient with Parkinson’s disease
and there is no pigment in the substantia nigra.
Multiple sclerosis
This is a condition which affects young adults.
The pathology consists in the presence of
multiple areas of demyelination throughout the
nervous system, particularly in the optic nerve,
around the ventricles in the brain, and in the
spinal cord.
Because these areas of demyelination occur in
many areas the symptoms are protean and
depend on the area of the nervous system that is
affected.
Characteristically the symptoms regress after an
acute attack and recur weeks or months later.
Permanent damage develops as the disease
progresses.
One of the common presentations is with optic
neuritis in which there is loss of vision in one
eye.
Another presentation is muscle weakness when
the plaque affects the anterior horns of the
spinal cord.
Balance is affected when the plaque is situated
in the posterior columns of the spinal cord.
Intracerebral plaques may cause motor
weakness, cerebellar ataxia and psychiatric
disorders.
58 Brain from a middle aged woman who died
from intercurrent infection after many years of
having protean problems from multiple
sclerosis. Note the large grey areas of
demyelination that are periventricular in
distribution. (red arrows)
Infections
Many different infectious agents may cause
infection of the nervous system.
Bacteria
Viruses
Fungi
Parasites
Meningitis
This is the condition most frequently
encountered in this category of disease.
Meningitis is defined as an inflammation of the
leptomeninges.
It results in the accumulation of purulent
exudate in the subarachnoid space.
This is seen grossly as creamy opaque material
in the subarachnoid space. (See Fig. 57)
(a)
(b)
59(a) and (b)
Meningitis
(a) shows the undersurface of the cerebellum.
19
There is opacity of the leptomeninges covering
the outlets to the CSF flow from the 4th
ventricle. (red arrow)
(b) This has caused some obstruction to the
CSF flow as can be seen from the mild
dilatation of the lateral and third ventricles.
Most cases of meningitis can be cured by
antibiotic treatment, but even with effective
treatment some patients still die from this
infection.
Organisms that most commonly cause
meningitis
Haemophilus influenzae
Neisseria meningitidis
Streptococcus pneumoniae
Organisms that are less common causes
Mycobacteruim tuberculosis
Staphyloccus aureus
Cryptococcus neoformans
Free-living amoebae (Naegleria)
Orgnaisms that cause meningitis particularly in
neonates
Coliform organisms
Listeria monocytogenes
Group B Streptococci
Diagnosis is confirmed by lumbar puncture
which allows one to obtain a sample of CSF
from the subarachnoid space for microscopic
examination and culture of the causative
organism.
Neonatal meningitis
The organisms that cause meningitis in
neonates are somewhat more resistant to
treatment than those encountered at an older
age.
When death occurs, one finds at postmortem a
marked amount of thick pus in the
subarachnoid space.
60 Neonatal meningitis.
The black arrow indicates the thick pus in the
subarachnoid space.
The red arrow shows the pons which has had
the leptomeninges accidentally stripped from it
during removal from the skull.
61 meningitis x10.
Microscopic section of meningitis.
Pus is filling the subarachnoid space (black
arrow) and extending into the brain in the
Virchow Robin space which is an extension of
the subarachnoid space that accompanies an
artery as it enters the brain substance.
Cerebral abscess
An abscess occurs when there is an
accumulation of pus in the brain or spinal cord.
Abscesses may occur as a result of direct spread
of infection from middle ear infection or from
paranasal sinus infections.
An abscess from this cause is usually a single
lesion.
62 Transverse sections of the medulla and
spinal cord from a male 10 months who died
from meningitis and speticaemia from infection
of a meningomyelocoele.
.
The red arrow indicates an abscess in the
medulla.
Green arrow normal pyramids.
Orange arrow pus filling the subarachnoid
space of the spinal cord. (meningitis)
This 10month old baby died from infection of a
meningomyelocoele.
Abscesses may also be caused by organisms
spread via the blood stream such as is seen in
emboli from infective endocarditis.
Abscess from this cause are usually multiple.
(a)
(b)
63(a) and (b) These are slices through the
whole brain from frontal to occipital poles from
a patient who died from the effects of infective
endocarditis.
Many of the multiple abscesses are indicated by
red arrows.
Note that these two Figs. demonstrate the
anatomy of the whole brain, and they can be
used to identify the various anatomical
20
structures and neuroanatomical pathways that
have been already demonstrated.
(The brain stem and cerebellum have been
removed so that they could be examined
separately and are not included in these
images.)
Viral infections
Encephalitis is the name given to a viral
infection of the brain.
A number of viruses cause encephalitis, but
Herpes simplex virus is the commonest cause.
It occurs in people of all ages.
Characteristically this infection causes necrosis
of the temporal lobes.
Treatment with antiviral agents produces good
results.
64 A female 66 years who died from Herpes
simplex encephalitis.
The brain is examined from the anterior aspect.
The right temporal lobe shows extensive
necrosis caused by the infection. (red arrows)
This macroscopic appearance is characteristic
of Herpes simplex infection.
Tumours
As in all organs, tumours may be primary or
secondary, benign or malignant.
Benign tumours
Meningiomas which arise from the fibrous
tissue of the meninges.
Neurofibromas (neurilemmomas) which arise
from the connective tissue sheaths of nerves.
Colloid cyst.
Meningioma
These tumours can occur anywhere in the
nervous system – within the skull or vertebral
column.
They grow slowly and cause pressure
symptoms as they expand.
The exact symptoms depend on their site of
origin and the critical structures in their
vicinity.
They may penetrate right through the skull and
appear as sub cutaneous tumours.
This is not a manifestation of malignancy.
They may become calcified.
Occasionally a benign tumour may recur and
show features of malignancy.
65 This specimen shows a meningioma (red
arrow) arising from the dura mater of the
middle of the skull.
In this position it causes pressure on the
underlying cerebral cortex.
When the pressure is exerted on the pre central
gyrus, it results in paraplegia with paralysis of
both legs.
66 A large meningioma is invading the left
cerebral hemisphere, enlarging this and causing
pressure atrophy on surrounding brain tissue,
and shift across the midline to the right with
compression of that hemisphere as well.
Apart from causing raised intracranial pressure
and epileptic fits, meningiomas involving the
frontal lobes may cause dementia.
One of the routine investigations in any case of
dementia is an imaging examination of the
brain to exclude this type of tumour.
67 X ray of a patient who had been having
epileptic fits and deteriorating mental function
for some years.
Blue arrow shows a calcified meningioma.
The overlying skull (red arrow) shows some
proliferative thickening of the diploe which is a
reactive change to the meningioma.
Neurofibroma (neurilemmoma)
These tumours arise from cranial or spinal
nerves.
They cause symptoms from pressure effects as
they slowly expand.
They may also arise on peripheral nerves.
Retroperitoneal and intrathoracic
Neurofibromas arise from the autonomic
nerves.
When they first give rise to symptoms they are
usually quite large.
In spite of the necrosis and cystic change, they
are virtually never malignant.
]
Neurofibromatosis
This is a condition that is transmitted as an
autosomal dominant trait.
21
It consists in the development of multiple
neurofibromas on nerves throughout the body.
The most obvious sites are subcutaneous
nerves, in which they present as multiple
subcutaneous soft lumps all over the body.
Very occasionally malignant change develops
in these tumours.
68 Cut surface of a large neurofibroma
removed surgically from the retroperitoneum.
Characteristically, and as shown here, the
tumour undergoes necrosis and cystic change.
region and this results in ‘coning’ in which the
cerebellar peduncles herniate through the
foramen magnum.
71 Colloid cyst of the third ventricle.
Medial view of the anterior half of the right
cerebral hemisphere.
The red arrow indicates a colloid cyst that has
arisen at the anterior end of the third ventricle
where it was causing intermittent obstruction of
the foramena of Munro.
Malignant tumours
69 Cut surface of a neurofibroma from the
mediastinum. It shows cystic degeneration.
70 Amputation neuroma.
This tumour occurs at the site of cutting of the
nerve.
It consists of a proliferation of nerve fibres.
This may result from trauma, or as a post
operative complication in which a small nerve
is severed.
Such tumours are usually painful.
They are called ‘amputation neruomas.’
Colloid cyst
This is a benign cyst that almost always arises
from the ependymal lining of the anterior end
of the third ventricle.
It has a thin wall consisting of a single layer of
cuboidal cells and it is filled with colloid fluid.
It grows slowly and usually reaches the size of
the one in the specimen before causing
symptoms that lead to its diagnosis.
It causes pathognomonic symptoms.
Intermittent headache present when the head is
down.
The headache is relieved when the head is
raised.
It is easy to diagnose with imaging techniques
and it is easy to remove surgically.
However, if it becomes ‘stuck’ in the orifice of
one or both foramena of Munro, death occurs as
a result of raised intracranial pressure.
A few deaths have been reported following
lumbar puncture performed with the patient
sitting up.
Removal of CSF during lumbar puncture
results in reduction of pressure in the spinal
Primary
These tumours arise from the various cell
components of the nervous tissue.
Astrocytoma
Oligodendroglioma
Ependymoma
Medulloblastoma
Others
Astrocytoma
These are the commonest cell type and they
arise from the astrocytes in the brain and spinal
cord.
They occur at all ages.
Some astrocytomas grow rapidly and cause
death within a few weeks or months after first
diagnosis.
This biological behaviour correlates with the
cytological appearances of the tumour.
Haemorrhage into the tumour is often the
immediate cause of death.
Spread beyond the skull is distinctly rare.
Oligodendrogliomas have a significantly better
prognosis than astrocytomas.
Tumours that have mixed oligodendroglioma
and astrocytoma cytology are frequently
encountered.
72 This brain shows the presence of an
astrocytoma (red arrow) that has arisen from
the deep part of the left hemisphere.
It has infiltrated the adjacent brain tissue and
into the third ventricle and caused shift of the
brain towards the right.
22
The tumour shows the presence of areas of
necrosis and haemorrhage.
These features are those of a rapidly growing,
high grade tumour.
The blue arrow indicates the large amount of
oedema in the white matter as a reaction to the
tumour.
73 An astrocytoma that has arisen in the left
hemisphere and extended through the corpus
callosum into the right hemisphere.
Both hemispheres show the presence of marked
oedema.
The tumour is fairly solid and homogeneous, so
it may not be as high grade as the one in Fig.
74 This astrocytoma has undergone marked
haemorrhage. Sudden haemorrhage into a
tumour is a common terminal event.
(a) x4
(b)x10
75(a) and (b) show the microscopic appearance
of an astrocytoma.
The brain tissue on the right is almost normal
and of normal cellular density.
The brain on the left is markedly hypercellular
and the cells resemble astrocytocytes.
The increased cellularity of the brain tissue is
the low magnification indication that there is a
tumour present.
At the x10 magnification the tumour cells can
be seen to resemble astrocytes. They are of
fairly uniform appearance and there is no
pleomorphism.
This is a low grade (grade 2) atrocytoma on
cytological grounds.
76 On gross examination it appears as though
this tumour has arisen within the third ventricle.
On microscopic examination the tumour was
shown to be an ependymoma.
Ependymomas arise from ependymal lining
cells anywhere in the ventricular system of the
brain.
Brain tumours in children
Brain tumours are among the commonest solid
tumours of children.
In children the majority of brain tumours arise
in the posterior fossa, that is beneath the
tentorium cerebelli.
Medulloblastoma is a specific tumour that
arises from the fourth ventricle in the
cerebellum of children.
It characteristically spreads in the subarachnoid
space over the spinal cord.
77 This is a horizontal section through the
middle of the cerebellum.
There is a tumour within the fourth ventricle.
(red arrow)
It is expanding and occluding the ventricle.
This is the characteristic gross appearance of a
medulloblastoma.
Astrocytomas may arise in this site, but
medulloblastomas have a characteristic
microscopic appearance, and the exact
diagnosis must be confirmed by microscopic
examination.
Children with medulloblastomas usually
present with balance problems and they keep
falling over.
Headaches and vomiting may also be present as
a result of the raised intracranial pressur.
78 This is a brain stem tumour that arose in a
male aged 3 years.
Haemorrhage has been the terminal event.
This is one of the subtentorial anatomical sites
for astrocytomas that occur in children.
Metastatic tumours
Any tumour may spread to the brain.
Lung, breast and melanoma are among the
commonest metastatic brain tumours.
As in other organs, for example the lung,
metastatic (secondary) tumours are usually
multiple.
79 Slice of a brain showing two metastatic
deposits (blue arrows) of tumour. Microscopic
examination showed that they arose from a
primary lung tumour.
23
80 Brain slice showing the presence of two
metastatic deposits of tumour (red arrows).
Microscopically they were seen to be from a
primary breast cancer.
The blue arrow indicates choroid plexus in the
right lateral ventricle.
(a) This is the eye from a young adult who
complained of visual disturbance, including
bumping into things.
Examination with an ophthalmoscope showed
the presence of this black tumour arising from
the retina of the posterior chamber of the eye.
The eye was removed surgically.
Eye pathology
(b)
Two eye tumours are included because of their
interest.
Retinoblastoma in children.
Melanoma in adults.
Retinoblastoma
81 This eye was removed surgically because of
a diagnosis of retinoblastoma.
The tumours often present because the mother
notices that the pupil has become white.
This is due to the colour of the tumour that is
replacing the posterior chamber of the eye.
The eye has been sliced and the two slices laid
side by side.
The optic nerve (black arrow) can be seen in
the top of the specimen.
In this case the retinoblastoma has arisen from
the retina in a multifocal fashion. (red arrows)
Usually it is a single mass of tumour.
These tumours arise in the eyes of children in
the first few years of life.
They spread along the optic nerve which
accounts for the length of the surgically excised
optic nerve in this case.
They often spread to the opposite eye.
They are often familial.
They may be bilateral at first presentation.
Blue arrow cornea.
Yellow arrow lens.
Purple arrow sclerotic.
Melanoma
82(a) and (b) Melanoma
(a)
(b) Section of the eye (x1 magnification)
confirmed that the tumour was a heavily
pigmented melanoma. (red arrow)
Blue arrow cornea
Green arrow iris diaphragm which forms the
posterior border of the anterior chamber of the
eye
Yellow arrow ciliary body
Orange arrow lens
Black arrow retina
Purple arrow sclerotic