Mr. Mallappa Shalavadi
HSK College of Pharmacy, Bagalkot
Water on the brain
Formation and circulation of cerebrospinal
Cerebrospinal fluid (CSF) is a clear, colorless
liquid that protects the brain and spinal cord
from chemical and physical injuries.
It also carries oxygen, glucose, and other needed
chemicals from the blood to neurons and
CSF continuously circulates through cavities in the
brain and spinal cord and around the brain and
spinal cord in the subarachnoid space (between
the arachnoid mater and pia mater).
Below fig., shows the four CSF-filled cavities within the brain, which are
called ventricles (VEN-tri-kuls little cavities). A lateral ventricle is located
in each hemisphere of the cerebrum. Anteriorly, the lateral ventricles are
separated by a thin membrane, the septum pellucidum (SEP-tum pe-LOO-
sidum; pellucid transparent). The third ventricle is a narrow cavity along
the midline superior to the hypothalamus and between the right and left
halves of the thalamus. The fourth ventricle lies between the brain stem
and the cerebellum.
The CSF contributes to homeostasis in three main ways:
1. Mechanical protection. CSF serves as a shock-
absorbing medium that protects the delicate tissues of the
brain and spinal cord. The fluid also buoys the brain so
that it “floats” in the cranial cavity.
2. Chemical protection. CSF provides an optimal chemical
environment for accurate neuronal signaling. Even slight
changes in the ionic composition of CSF within the brain
can seriously disrupt production of action potentials and
3. Circulation. CSF allows exchange of nutrients and
waste products between the blood and nervous tissue.
Formation of CSF
The sites of CSF production are the choroid plexuses (KO¯ -
royd membrane like), networks of blood capillaries
(microscopic blood vessels) in the walls of the ventricles.
The capillaries are covered by ependymal cells that form
cerebrospinal fluid from blood plasma by filtration and
Because the ependymal cells are joined by tight junctions,
materials entering CSF from choroid capillaries cannot leak
between these cells; instead, they must pass through the
This blood–cerebrospinal fluid barrier permits certain
substances to enter the CSF but excludes others, protecting
the brain and spinal cord from potentially harmful blood
Circulation of CSF
The CSF formed in the choroid plexuses of each lateral ventricle
flows into the third ventricle through two narrow, oval openings, the
More CSF is added by the choroid plexus in the roof of the third
The fluid then flows through the aqueduct of the midbrain (cerebral
aqueduct), which passes through the midbrain, into the fourth
The choroid plexus of the fourth ventricle contributes more fluid.
CSF enters the subarachnoid space through three openings in the
roof of the fourth ventricle: a median aperture and the paired
lateral apertures, one on each side.
CSF then circulates in the central canal of the spinal cord and in the
subarachnoid space around the surface of the brain and spinal cord.
CSF is gradually reabsorbed
into the blood through
arachnoid villi, fingerlike
extensions of the arachnoid
that project into the dural
venous sinuses, especially the
superior sagittal sinus (A
cluster of arachnoid villi is
called an arachnoid
granulation.) Normally, CSF
is reabsorbed as rapidly as it
is formed by the choroid
plexuses, at a rate of about
20 mL/hr (480 mL/day).
Because the rates of
formation and reabsorption
are the same, the pressure of
CSF normally is constant.
In adults, children, and infants the volume of CSF is approximately
150 mL, 60 to 100 mL, and 40 to 60 mL, respectively.
Normal values (CSF):
CSF opening pressure: 50–180 mmH2O
Glucose: 40–85 mg/dL.
Protein (total): 15–45 mg/dL.
Lactate dehyrogenase: 1/10 of serum level.
Lactate: less than 35 mg/dL.
Leukocytes (WBC): 0–5/µL (adults / children); up to 30/µL
Specific gravity: 1.006–1.009.
Syphilis serology: negative.
Gross appearance: Normal CSF is clear and colorless.
Differential: 60–70% lymphocytes; up to 30%
monocytes and macrophages; other cells 2%
also known as "water on the brain," is a medical
condition in which there is an abnormal
accumulation of cerebrospinal fluid (CSF) in the
ventricles, or cavities, of the brain.
Types of Hydrocephalus
Based on its underlying mechanisms, hydrocephalus can be classified
into communicating and non-communicating (obstructive). Both
forms can be either congenital or acquired.
Communicating hydrocephalus, also known as non-
obstructive hydrocephalus, is caused by impaired cerebrospinal
fluid reabsorption in the absence of any CSF-flow obstruction
between the ventricles and subarachnoid space.
this is due to functional impairment of the arachnoidal
granulations (also called arachnoid granulations or Pacchioni's
granulations), which are located along the superior sagittal sinus
and is the site of cerebrospinal fluid reabsorption back into the
Various neurologic conditions may result in communicating
hydrocephalus, including subarachnoid/intraventricular
hemorrhage, meningitis and congenital absence of arachnoid villi.
Scarring and fibrosis of the subarachnoid space following
infectious, inflammatory, or hemorrhagic events can also prevent
resorption of CSF, causing diffuse ventricular dilatation.
Normal pressure hydrocephalus (NPH) is a particular
form of communicating hydrocephalus, characterized by
enlarged cerebral ventricles, with only intermittently
elevated cerebrospinal fluid pressure.
Hydrocephalus ex vacuo also refers to an enlargement
of cerebral ventricles and subarachnoid spaces, and is
usually due to brain atrophy (as it occurs in dementias),
post-traumatic brain injuries and even in some
psychiatric disorders, such as schizophrenia.
Non-communicating hydrocephalus, or obstructive
hydrocephalus, is caused by a CSF-flow obstruction
ultimately preventing CSF from flowing into the
subarachnoid space (either due to external compression or
intraventricular mass lesions).
Foramen of Monro obstruction may lead to dilation of
one or, if large enough (e.g., in Colloid cyst), both lateral
The aqueduct of Sylvius, normally narrow to begin with,
may be obstructed by a number of genetically or
acquired lesions (e.g., atresia, ependymitis, hemorrhage,
tumor) and lead to dilation of both lateral ventricles as
well as the third ventricle.
Fourth ventricle obstruction will lead to dilatation of the
aqueduct as well as the lateral and third ventricles (e.g.,
The foramina of Luschka and foramen of Magendie
may be obstructed due to congenital failure of opening
(e.g., Dandy-Walker malformation).
The cranial bones fuse by the end of the third year of life.
For head enlargement to occur, hydrocephalus must
occur before then.
The causes are usually genetic but can also be acquired
and usually occur within the first few months of life, which
1) intraventricular matrix hemorrhages in premature
3) type II Arnold-Chiari malformation
4) aqueduct atresia and stenosis
5) Dandy-Walker malformation.
This condition is acquired as a consequence of
intracranial hemorrhage (subarachnoid or
intraparenchymal) is usually extremely painful.
In infants with hydrocephalus
Eyes that appear
to gaze downward
Symptoms that may occur in older
children can include:
Brief, shrill, high-pitched cry
Changes in personality, memory, or
the ability to reason or think
Changes in facial appearance and
Crossed eyes or uncontrolled eye
Irritability, poor temper control
Loss of bladder control (urinary
Loss of coordination and trouble
Muscle spasticity (spasm)
Slow growth (child 0–5 years)
Slow or restricted movements
Exams and Diagnostic Tests
The doctor will examine the baby. This may show:
Stretched or swollen veins on the baby's scalp
Abnormal sounds when the health care provider taps lightly on the
skull, suggesting a problem with the skull
All or part of the head may be larger than normal, usually in the
Eyes that look "sunken in"
White part of the eye appears over the colored area, making it look
like a "setting sun"
Reflexes may be normal
Head circumference measurements, repeated over time, may show
that the head is getting bigger.
A head CT scan is one of the best tests for identifying
Other tests that may be done include:
Brain scan using radioisotopes
Cranial ultrasound (an ultrasound of the brain)
Lumbar puncture and examination of the cerebrospinal
fluid (rarely done)
Magnetic resonance imaging.
The goal of treatment is to reduce or prevent brain
damage by improving the flow of CSF.
Surgery may be done to remove a blockage, if possible.
If not, a flexible tube called a shunt may be placed in the
brain to re-route the flow of CSF.
The shunt sends CSF to another part of the body, such as
the belly area, where it can be absorbed.
Other treatments may include:
Antibiotics are given if there are signs of infection.
Severe infections may require the shunt to be removed.
A procedure called endoscopic third ventriculostomy
(ETV), which relieves pressure without replacing the
~ 100% reliability (although 50%
of current shunts are replaced
within 5 years)
~75% of patients are treated by
this methodology3. Ventriculostomy
When first developed the
procedure had high mortality
and morbidity rates. Today it is
a very safe procedure
~25% of patients are treated
by this methodology
Initially, it was shown that
Acetazolamide reduced CSF
production by the choroid
In a series of Hydrocephalus in
immature infants the drug was
used and success was claimed
as shunts was avoided in 50%
of the cases
0% of patients are treated by
Shunting is the
Most shunts drain the fluid into the peritoneal cavity
(ventriculo-peritoneal shunt), but alternative sites
include the right atrium (ventriculo-atrial shunt), pleural
cavity (ventriculo-pleural shunt), and gallbladder.
A shunt system can also be placed in the lumbar space
of the spine and have the CSF redirected to the
peritoneal cavity (Lumbar-peritoneal shunt).
An alternative treatment for obstructive hydrocephalus
in selected patients is the endoscopic third
ventriculostomy (ETV), whereby a surgically created
opening in the floor of the third ventricle allows the CSF
The SinuShunt vs. traditional shunts
SinuShunt Traditional shunts
Complications of ventriculoperitoneal shunt
The major possible complications are:
• infection of the shunt
• obstruction of the shunt
• intracranial haemorrhage.