1. EMERGENCIES IN NEUROSURGERY 2012
Symposium 7: Hydrocephalus
HYDROCEPHALUS
AND ITS CAUSES
29-9-2012
Dewan Auditorium, HTAA
2. WHAT IS HYDROCEPHALUS?
Abnormal build-up of cerebrospinal fluid
Ventricular System in the Brain or subarachnoid space
causes an increase in pressure
3. Ventricular System in the Brain
• Cerebral Spinal Fluid
(CSF) is mostly made in
the ventricular system of
the brain. This fluid then
circulates throughout the
brain as well as down the
spine.
4. Normal Cerebral Spinal Fluid Flow
• Most of the CSF is produced in
the body of the lateral
ventricle.
• Normally, it will flow from the
lateral ventricle down through
the Foramen of Monro into the
III ventricle.
• From there it proceeds down
the aqueduct into the IV
ventricle.
• There are three openings in
the IV ventricle:
– Laterally are the foramen of
Lushka
– Medially or in the middle is
the foramen of Magendie.
5. Cranio-caudal systolic CSF flow
cardiac systole
Transmission of cerebral
arterial pulsation
Monro-Kellie doctrine
The volume of the intracranial
contents (brain, CSF, blood)
remains constant all times.
Generalized expansion of the
intracranial volume
spinal subarachnoid space
Increase in intracranial volume is
dissipated by an outflow of CSF
from intracranial subarachnoid
spaces and the ventricular
system down to the compliant
spinal subarachnoid space,
Xavier Morandi *, Seyed F.A. Amlashi, Laurent Riffaud; Medical Hypotheses (2006) 67, 79–81
6. Caudo-cranial diastolic CSF flow
Diastole
decreased cerebral blood flow
The elastic property of the spinal dura
mater
CSF is pushed in the
opposite direction in the intracranial space
Xavier Morandi *, Seyed F.A. Amlashi, Laurent Riffaud; Medical Hypotheses (2006) 67, 79–81
7. Ventricular System in the Brain
• When there is too much
fluid in the ventricular
system, it dilates and can
squeeze the surrounding
brain tissue.
• This is hydrocephalus
8. Ventricular System in the Brain
• HYDROCEPHALUS
– Ventricular system is
becoming larger
– The ventricles are
becoming round
• Since the skull is a closed
space containing the
brain, increasing the size
of the fluid compartment
(the ventricles) begins to
displace the adjacent
parts of the brain
resulting in neurological
symptoms.
9. WHAT IS OBSTRUCTIVE
HYDROCEPHALUS?
• Obstruction to normal
cerebral spinal fluid
pathways may involve
any portion of the
ventricular system.
Multicompartmental model of ventricular volume regulation. (Rekate et al. 1988)
10. Obstructive Hydrocephalus: Example
• There is a mass (tumor) at the
level of the Foramen of
Monroe and the III Ventricle.
• The CSF flow is obstructed
and cannot flow down into the
III Ventricle to the aqueduct,
into the IV ventricle and then
out around the brain and down
into the spinal cord.
• The ventricular system is
enlarged proximal to (before)
the level of the blockage.
• Both lateral ventricles,
especially the frontal horns are
dilated.
14. Obstructive Hydrocephalus:
Aqueductal Stenosis
• Aqueductal Stenosis is seen
mostly in infants and young
adults.
• It can present later on in the
teenage years as well.
• With more and more people
having CT and MRI brain scans,
we are seeing people in their 50's
and even 70's (adult) with
aqueductal stenosis.
• Essentially, the aqueduct is
atretic
• Since cerebral spinal fluid (CSF)
cannot flow down into the IV
Ventricle, obstructive
hydrocephalus develops.
• Characteristically, everything
proximal to the aqueduct dilates.
The IV Ventricle remains normal
in size.
15. Aqueductal Stenosis : CT Scan
• The frontal horns, the III
ventricle and the temporal
horns are all enlarged.
• The IV ventricle which is
distal to the aqueduct is
normal in size.
16. Obstructive Hydrocephalus: TUMOR
• Cerebellar Brain Tumor
pushing on the IV Ventricle
• This is a common location
where brain tumors cause
hydrocephalus, invading the
IV ventricle and blocking
CSF (cerebral spinal fluid)
flow
• Sometimes strokes or
hemorrhages may cause this
sequence of events as well.
17. Obstructive Hydrocephalus: TUMOR
• Cerebellar Brain Tumor pushing
on the IV Ventricle
• The CT Scan shows a cross
section of the problem in a patient
with a cerebellar tumor and
swelling.
• The CSF can flow down its usual
pathway, but it is beginning to
become obstructed by the tumor.
• Unless treated, as the tumor
grows the ventricle will close off
and obstructive hydrocephalus
will develop.
• Symmetry of the IV ventricle is
lost. The black in the IV Ventricle
is Cerebral Spinal Fluid. The
lighter grey tissue is the
cerebellum.
• The darker grey tissue is tumor
plus swollen cerebellum.
18. Obstructive Hydrocephalus: CYST
• Loculated cysts in the III
ventricle causing early
obstructive hydrocephalus
• The MRI shows an enlarged
III ventricle.
• There are loculated cysts
within the III ventricle.
• These cyst formed due to
scarring from a patient with
meningitis.
• CSF cannot flow past the III
ventricle, so the lateral
ventricles begin to enlarge.
• The aqueduct and IV ventricle
are normal in size.
19. Obstructive Hydrocephalus: CYST
• Enlarged III Ventricle
With Development of
Early Hydrocephalus
• The CSF can flow down
its usual pathway, but it is
beginning to become
obstructed by the
enlarged III ventricle.
• Unless treated,
obstructive
hydrocephalus will
develop.
20. Obstructive Hydrocephalus: CYST
• Porencephalic Cyst and
Enlarged Ventricles... is this
Hydrocephalus?
• When a cyst communicates (is
continuous with) one of the
ventricles, it is usually
congenital (formed during
pregnancy).
• There is a large cerebellar cyst
communicating with an enlarged
IV ventricle.
• The III ventricle is mildly
enlarged as well. Is this early
hydrocephalus?
21. Obstructive Hydrocephalus:
HYPERTENSIVE HEMORRHAGE
• Bleeding into the brain from high
blood pressure causing early
obstructive hydrocephalus
• The CT Scan shows an enlarged
ventricular system.
• CSF cannot flow past the blood
clot so the lateral ventricles
begin to enlarge.
• High blood pressure
(Hypertension) is a common
cause of brain hemorrhages.
• When hemorrhages occur from
hypertension, many times the
patient will bleed into the
ventricular system and/or into
the surrounding brain structures.
• These structures are often the
thalamus and basal ganglia.
22. Obstructive Hydrocephalus:
HYPERTENSIVE HEMORRHAGE
• Bleeding into the brain
from high blood pressure
causing early obstructive
hydrocephalus
• The CSF can flow down
its usual pathway, but it is
beginning to become
obstructed by the
hemorrhage.
• Obstuctive hydrocephalus
is developing
23. COMMUNICATING
HYDROCEPHALUS
• Communicating hydrocephalus
develops when there is more fluid
being produced than can be
absorbed.
• The ventricular system enlarges to
hold the excess fluid.
• This compresses the surrounding
brain tissue.
• Communicating Hydrocephalus
may result from various types of
hemorrhages.(Post
Hemorrhagic, Subarachnoid
Hemorrhage, Other Hemorrhage).
• There is a special case of
Communicating Hydrocephalus
called Normal Pressure
Hydrocephalus.
24. Communicating Hydrocephalus: CT
Scan
• Notice how all the
ventricles are
enlarged. Compare
this image to the CT
Scans below.
Normal, No Hydrocephalus: CT Scan
25. Communicating Hydrocephalus:
SUBARACHNOID HEMORRHAGE
• Bleeding into the brain from an
aneurysm rupture may cause
communicating hydrocephalus
• The CT Scan to the left shows an
enlarging ventricular system.
• The blood results in decreased
absorption of the CSF.
• The production of CSF continues
so a net increase of CSF occurs.
• Thus, the ventricles begin to
enlarge.
• About 10% of people who suffer
SAH (subarachnoid hemorrhage)
develop hydrocephalus.
26. Communicating Hydrocephalus:
SUBARACHNOID HEMORRHAGE
• Delayed communicating
hydrocephalus from SAH
• Sometimes hydrocephalus is not
apparent during the acute
treatment of an aneurysm rupture.
• It may present itself several
months later.
• Follow-up CT scans are important
to diagnose delayed
hydrocephalus if clinically
indicated.
28. Communicating Hydrocephalus:
NORMAL PRESSURE
HYDROCEPHALUS (NPH)
• MRI scans and normal pressure
hydrocephalus
• The MRI scan usually
demonstrates large ventricles.
• In elderly individuals there may
be cerebral atrophy (shrinkage
of the gray matter).
• Cerebral Spinal Fluid will fill up
the space of a brain with
atrophy.
• However, in NPH, the enlarged
fluid space (ventricles) are
enlarged out of proportion to the
cerebral atrophy.
29. 1913 Johns Hopkins University
Dr. Walter Dandy
The first studies in experimental animals related to the
injection of a supravital dye into the ventricle and
attempting to recover it from the spinal subarachnoid space
(SSAS) via lumbar puncture.
communicating
non-communicating
“obstructive”
30. Why questions the simple
classification of Dandy?
• Some patients who developed
hydrocephalus in infancy or had arachnoid
cysts treated with shunts in infancy
develop severely increased intracranial
pressure with no expansion of the
ventricles or cyst at the time of shunt
failure
• Never lead to the understanding of normal
pressure hydrocephalus (NPH) and
pseudotumor cerebri (PC)
31. CSF dynamics
• Techniques for the study of CSF dynamics
had improved dramatically since the
studies of Dandy.
• Tools such as magnetic resonance
imaging (MRI), Cine MRI flow studies,
cisternography utilizing dye studies and
especially long-term studies of the
outcomes of treatment decisions make it
possible to accurately define a point of
restriction of flow.
32. CSF compliance
• Between 30% and 70% of total CSF system
compliance has been attributed to the spinal
compartment
• The remaining one to two third of CSF system
compliance consists of changes in the vascular pool,
especially the intracranial venous system (Vascular
compliance)
• These two systems are in equilibrium instantaneously
and any variations in either compartment result in rapid
compensatory changes in the other
Compliance= to the ratio of volume and pressures changes (dV/dP)
Xavier Morandi *, Seyed F.A. Amlashi, Laurent Riffaud; Medical Hypotheses (2006) 67, 79–81
33. Compliance of the spinal compartment
• Based on
– an increased elasticity of the spinal dura mater
– a wide epidural space with an extended
compressible epidural venous plexus
– sub-atmospheric epidural pressure
Xavier Morandi *, Seyed F.A. Amlashi, Laurent Riffaud; Medical Hypotheses (2006) 67, 79–81
34. ICD 10
Until now there has been no consensus as
to a more
contemporary classification scheme
35. Members of the Hydrocephalus
Classification Study Group
January of 2010
36. The structure of the consensus
First level of
classification of hydrocephalus
Based on the point
where the flow of CSF is restricted
Foramina of Monro,
The aqueduct of Sylvius,
The basal cisterns,
The arachnoid granulations,
Outflow of venous blood from the dural
venous sinuses
without a point of
obstruction or increased resistance to flow.
communicating hydrocephalus
overproduction of CSF
(e.g. by choroid
plexus papillomas)
Second level of
classification of hydrocephalus
Modified by
The etiology
The chronicity or rapidity of onset
The age of the person
