Hydrocephalus is an abnormal increase in cerebrospinal fluid in the cranial cavity that causes expansion of the ventricles and skull. It can be communicating or non-communicating depending on whether CSF can circulate between the ventricles and subarachnoid space. The most common cause of non-communicating hydrocephalus is aqueductal stenosis which is a blockage of the aqueduct, while post-infectious hydrocephalus is a common cause of communicating hydrocephalus. Treatment often involves surgically placing a ventriculoperitoneal shunt to drain excess CSF from the brain to the abdomen.

1. HYDROCEPHALUS

2. Hydrocephalus
 Definition:
An abnormal increase in the amount of
cerebrospinal fluid within the cranial cavity
that is accompanied by expansion of the
cerebral ventricles, enlargement of the skull
and especially the forehead, and atrophy of
the brain

3. Overview of CSF
production
 The CSF volume
ranges from 80 to
160 ml
 CSF is produced
in the choroid
plexuses at a daily
rate of 14-36 ml/hr

4. Overview of CSF circulation
 The CSF flows from the lateral
ventricles downward to the
foramina of Magendie and
Luschka, to the subarachnoid
spaces, and then upward to the
basal cistern and finally to the
superior and lateral surfaces of the
cerebral hemispheres

5. The function of the CSF
 The CSF acts
as a “water
jacket” for the
brain and
spinal cord

6. Communicating vs. Non-
communicating (Dandy)
 This is an old
classification of
hydrocephalus
 The terms refer to the
presence or absence of a
communication of the
lateral ventricles with the
spinal subarachnoid

7. Communicating vs. Non-
communicating
 This classification was based on the imaging
findings after injection of dye into the
ventricular system and simultaneous injection
of air into the subarachnoid space
 Diffusion of dye into the subarachnoid space
and passage of air into the ventricular space
were the criteria for communicating
hydrocephalus

8. Non-communicating
hydrocephalus
 There is no communication between
the ventricular system and the
subarachnoid space. The commonest
cause of this category is aqueduct
blockage or stenosis.

9. Aqueductal stenosis
 The normal
aqueduct measures
about 1 mm in
diameter, and is
about 11 mm in
length.

10. Aqueductal stenosis
 Is the most common cause of congenital
hydrocephalus(43%)
 Aqueduct develops about the 6th week of
gestation
 M:F = 2:1
 Other congenital anomalies (16%): thumb
deformities
 Prognosis: 11-30% mortality

11. Clinical features of aqueductal
stenosis
 Obstructive
hydrocephalus: presents
with macrocephaly and/or
intracranial hypertension.
 Parinaud's syndrome.
Inability to elevate eyes
 Collier's sign. Retraction of
the eyelids

12. Communicating hydrocephalus
 In communicating or non-obstructive
hydrocephalus there is communication
between the ventricular system and the
subarachnoid space.
 The commonest cause of this group is
post-infectious and post-hemorrhagic
hydrocephalus.

13. Causes of communicating
hydrocephalus
 Overproduction of
CSF
 Blockage of CSF
circulation
 Blockage of CSF
resorption

14. Overproduction of CSF
 Excessive secretion of
CSF by the choroid
plexus as in cases of
choroid plexus
papilloma or
carcinoma. This is a
rare cause.

15. Blockage of CSF circulation
 This could be at any level of
the CSF circulation. It could
be at the level of the foramen
of Monro, with either
unilateral or bilateral
occlusion of the foramen of
Monro giving dilatation of one
or both lateral ventricles. This
is commonly seen in the
colloid cyst and tumors of the
third ventricle.

16. Dandy Walker Syndrome
 A common cause of
obstructive
hydrocephalus is
Dandy Walker
Syndrome where there
is blockage of foramina
of the 4th ventricle.

17. Blockage of CSF resorption
 Poor resorption of
CSF into the venous
sinuses caused by
scarring of the
arachnoid villi and is
commonly seen after
meningitis or
hemorrhage

18. Treatment of
hydrocephalus
 The two most commonly
used shunt systems are the
 ventriculoatrial (VA)
 The VP ventriculoperitoneal
shunts. nt is most commonly
used as it placed in the
peritoneum and the
consequences of infection

19. Common complications of VP
shunt
 shunt malfunction
 blockage
 infection.