2. Definition:
• Hydrocephalus is a disorder in which an excessive
amount of cerebrospinal fluid (CSF) accumulates within
the cerebral ventricles and/or subarachnoid spaces,
which are dilated.
• Hydrodynamic disorder of CSF
• In hydrocephalus imbalance exists between the
production of the CSF and its Absorption.
• It may be due to its increased production or reduced
absorption.
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4.
5. • The CSF volume, estimated to be about 150 ml
in adults, is distributed between 125 ml in
cranial and spinal subarachnoid spaces and 25
ml in the ventricles, but with marked
interindividual variations.
• CSF secretion in adults is around 500 ml per day,
depending on the subject and the method used
to study CSF secretion.
6. Arachnoid granulations contain many villi that are
able to act as a one-way valve helping to regulate
pressure within the CSF, and these arachnoid villi
push through the dura and into the venous
sinuses.
7.
8. • Physiological values of CSF pressure vary according to
individuals and study methods between 10 and 15
mmHg in adults and 3 and 4 mmHg in infants. Higher
values correspond to intracranial hypertension.
• CSF pressure varies with the systolic pulse wave,
respiratory cycle, abdominal pressure, jugular venous
pressure, state of arousal, physical activity and
posture.
9. Causes of hydrocephalus:
CONGENITAL HYDROCEPHALUS:
• Intrauterine infections: Rubella, Cytomegalovirus,
Toxoplasmosis.
• Trauma: Subarachnoid, Intracranial,
Intraventricular haemorrhages.
• Congenital malformations:
Dandy-walker syndrome:
Atresia of foramina of magendie
and luschka.
10. • Aqueduct stenosis: Stenosis of aqueduct of
sylvius causes dilatation of lateral and 3rd
ventricles.
Arnold-Chiari syndrome: Portions of
cerebellum & brainstem herniating into
cervical spinal canal, blocking the flow of CSF
into the posterior fossa.
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13. Types of hydrocephalus:
There are two types of hydrocephalus
Non-communicating(intraventricular or obstructive)
hydrocephalus-
• In this there is blockage between the ventricular &
subarachnoid systems, resulting in an interference
with circulation of CSF & lack of access to the
subarachnoid spaces.
• In this CSF distends the ventricles.
14. • There is a gradual thinning of the brain substance,
which is compressed between the distended
ventricles & the expanding skull.
• Non-communicating hydrocephalus may be due to
stenosis of the aqueduct of Silvius, either a
congenital defect or acquired.
• Obstructive hydrocephalus may result post-natally
from brain tumors that puts pressure on or extend
into the ventricles or circulation pathways.
15. Communicating
(extraventricular)hydrocephalus:
• In this there is normal communication between the
ventricles and the spinal subarachnoid space.
• There is an interference with the absorption of CSF
caused by an occlusion of the subarachnoid cisterns
around the brain stem.
• The fluid that is not absorbed in the subarachnoid
space accumulates, compressing the brain &
distending the cranial cavity.
16. • Communicating hydrocephalus may be due to
subarachnoid hemorrhage or meningitis,
toxoplasmosis or cytomegalovirus infection,
in which there is an obliteration of the
subarachnoid spaces by fibrous tissue
reaction, or to diseases of connective tissue.
17. Normal pressure hydrocephalus (NPH)
• It describes a condition that rarely occurs in patients
younger than 60 years.
• Enlarged ventricles and normal CSF pressure at
lumbar puncture (LP) in the absence of papilledema
led to the term NPH.
• Intermittent intracranial hypertension has been noted
during monitoring of patients in whom NPH is
suspected, usually at night.
• The classic Hakim triad of symptoms includes gait
apraxia, incontinence, and dementia.
• Headache is NOT a typical symptom in NPH
18. Clinical Manifestations:
Infants:
• Head grows at abnormal rate.
• Anterior fontanel is tense, often bulging, & non
pulsatile.
• Scalp veins are dilated & markedly so when
infant cries.
• Macewen’s sign- with increase in intracranial
volume, the bones of the skull become thin &
the sutures become palpably separated to
produce the cracked pot sound on the
percussion of the skull.
• Frontal bossing with depressed eyes.
• Setting Sun sign- eyes rotated downward, in
which sclera may be visible above iris.
22. Diagnostic evaluation:
Xray Skull.
Routine daily head (occipitofrontal)
circumference measurements in infants.
A head CT scan is one of the best tests for
identifying hydrocephalus.
Lumbar puncture and examination of the
cerebrospinal fluid (rarely done).
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23. • Brain imaging can help to distinguish obstructive
(non-communicating) from absorptive
(communicating) hydrocephalus.
• The site of obstructed CSF flow may be suggested
by the pattern of ventricular dilatation.
• Stenosis of the aqueduct (a common type of
obstructive hydrocephalus) typically results in
dilated lateral and third ventricles and in a fourth
ventricle of normal size.
• In contrast, communicating hydrocephalus (eg,
caused by either extra ventricular obstruction or by
impaired CSF absorption) in neonates and infants
usually results in symmetric dilatation of all four
ventricles.
24. This MRI axial image demonstrates dilatation of the
lateral ventricles.
27. Surgical management:
• The removal of the obstruction (tumor, hemorrhage or
cyst) to the flow of CSF.
• Reduction in the amount of CSF produced through
destruction of a portion of the choroid plexus or a
third or fourth ventriculostomy.
• Shunting of CSF from the ventricle to another site in
the normal circulatory passageway of this fluid.
• Shunting of CSF from the ventricle to an area outside
the CNS, an extracranial body compartment.
• Endoscopic Third ventriculostomy(ETV).
28. • Shunting is the most common procedure to
be done in the surgical management of
hydrocephalus.
• Most shunt systems consist of a ventricular
catheter, a flush pump, a unidirectional flow
valve & a distal catheter.
• All are radiopaque for easy visualization after
placement & all are tested before insertion.
30. Ventriculoperitonial(VP) shunt:
• This is the preferred procedure especially in
neonates & young infants.
• There is greater allowance for excess tubing,
which minimizes the number of revisions
needed as the child grows.
• In this ventricular catheter is inserted into the
anterior portion of a lateral ventricle through a
burr hole in the skull.
31. Ventriculoatrial(VA) shunt:
• It is reserved for older children who have attained
most of their somatic growth & children with
abdominal pathology.
• It requires repeated lengthening as child grows.
• A silicon catheter is inserted in lateral ventricle &
down through the internal jugular vein into left
atrium of the heart.
• The CSF drains into circulating blood.
• This type of shunt may become easily obstructed or
infected.
• If an infection occurs, bacterial endocarditis,
ventriculitis & bacteremia may result.
32. Endoscopic third ventriculostomy:
• It is a procedure that has potential for greater
independence from VP or VA shunting in
children with non-communicating
hydrocephalus.
• In this procedure a small opening is made in the
floor of the 3rd ventricle, allowing CSF to flow
freely through previously blocked ventricle, thus
bypassing the aqueduct of sylvius.
