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CNS DEVELOPMENT
Presenter: Justine D. Ngwanda
Supervisor: Dr. H. Rabiel
KCMU College
Surgical Department
INTRODUCTION
•The central nervous system (CNS) consists of
the brain and spinal cord and is protected by
the cranium and vertebral column.
•At the end of week two, a structure called the
Primitive streak appears as a groove in the
epiblast layer of the bilaminar disk.
•Cells within the epiblast migrate downward
through the primitive streak, giving rise to the
three layers from the initial two.
•These three germinal layers form the
trilaminar embryonic disc: Endoderm,
Mesoderm and the Ectoderm.
•The CNS is derived from the ectoderm, which
is the outermost layer of the embryonic disc.
SECOND WEEK
Differentiation of the embryo
into three germ layers :
•Ectoderm.
•Mesoderm.
•Endoderm.
•The Ectoderm will form
•(1) Central nervous system.
•(2) Epidermis of Skin.
NEURULATION
• In the 3rd week, the
notochord appears in the
mesoderm, which then
secretes growth factor i.e.
Sonic hedgehog (SHH), and
bone morphogenic proteins
(BMPs) which stimulates the
differentiation of the
underlying ectoderm into
Neuroectoderm, forming a
structure known as the
neural plate.
• On lateral edges of the
plate, form neural folds,
which meet in the midline,
fusing to form the Neural
tube which is a precursor to
the brain and spinal cord.
• During fusion of the neural
folds, some cells within the
folds migrate to form a
distinct cell population
known as Neural crest.
• The neural crest give rise to
diverse cell lineage
including melanocytes,
craniofacial cartilage and
bone, smooth muscles,
peripheral and enteric
neurons and glia.
• So, neurulation is the
formation of neural tube,
which is achieved by the
end of 4th week in the
region of 4th to 6th somites.
• So the first indications of
the developing nervous
system appear during the
third week as the neural
plate and neural groove
develop on the posterior
aspect of the trilaminar
embryo.
• At this stage, the cranial
two thirds of the neural
plate and tube as far
caudal as the fourth pair
of somites represent the
future brain, and the
caudal one third of the
plate and tube
represents the future
spinal cord.
• Fusion of the neural folds
and formation of the
neural tube begins at the
fifth somite and proceeds
in cranial and caudal
directions until only
small areas of the tube
remain open at both
ends.
• The lumen of the neural
tube becomes the neural
canal, which
communicates freely
with the amniotic cavity.
• The rostral neuropore
closes at approximately
the 25th day, and the
caudal neuropore closes
at approximately the
27th day.
• Syndecan 4 (SDC4) and
van gogh–like 2 (VANGL2)
proteins appear to be
involved with neural tube
closure.
• The neuroprogenitor cells
of the wall of the neural
tube thicken to form the
brain and spinal cord.
• The neural canal forms
the ventricular system of
the brain and the central
canal of the spinal cord.
THIRD WEEK
•Neural Plate :
•It is a dorsal midline
thickening of the
ectoderm overlying the
notochord
(Neuroectoderm) .
THIRD WEEK
•Neural Folds :
•They are the elevated
lateral margins of the
neural plate.
•They are on each side of
the longtudinal midline
(Neural Groove).
NEURAL TUBE
•It is formed from the
apposition and fusion
of the neural folds
which seal the neural
groove and create the
tube.
FOURTH WEEK
•The neural tube is completed
and transformed into the adult
CNS.
•This growth is maximal at the
rostral part which becomes
the brain.
•The caudal portion becomes
the spinal cord.
•The axis of the neural tube
(neuroaxis) is straight.
NEURAL GROOVE
•The central cavity
within the neural tube
becomes :
•Ventricles of the brain
and
•Central canal of the
spinal cord.
NEURAL CREST
• They are separated cells from the
apices of the neural folds.
• They are dorsolateral to the neural
tube.
• They give rise to :
• Autonomic ganglia.
• Sensory ganglia of spinal and cranial
nerves.
• Melanocytes.
• Cells of supra renal medulla.
DIFFERENTIATION OF SPINAL CORD
•The Grey matter is
located centrally
around the central
canal.
•The White matter
forms the outer
coat.
DIFFERENTIATION OF SPINAL CORD
• Sulcus Limitans :
• It is a longitudinal groove along the
inner surface of the lateral walls of
the developing spinal cord.
• It differentiates the grouping of
cells (gray matter),cells on the
dorsal side form the Alar plate,
which becomes the dorsal horn
(posterior) and cells at the ventral
end form the Basal plate, which
then becomes the ventral horn (
Anterior).
DIFFERENTIATION OF SPINAL CORD
•The Alar plate is
predominantly
sensory in function.
•The Basal plate is
predominantly
motor in function.
BIRTH DEFECTS OF SPINAL CORD
• Most defects result from failure of fusion of one or
more neural arches of the developing vertebrae during
the fourth week.
• NTDs affect the tissues overlying the spinal cord:
meninges, neural arches, muscles, and skin.
• Defects involving the embryonic neural arches are
referred to as spina bifida; subtypes of this defect are
based on the degree and pattern of the NTD.
• The term spina bifida denotes nonfusion of the halves
of the embryonic neural arches, which is common to
all types of spina bifida .
• Spina bifida ranges from clinically significant types to
minor defects that are functionally unimportant.
DERMAL SINUS
• A dermal sinus is lined with epidermis and skin
appendages extending from the skin to a deeper-lying
structure, usually the spinal cord.
• The sinus (channel) is associated with closure of the
neural tube and formation of the meninges in the
lumbosacral region of the spinal cord.
• The birth defect is caused by failure of the surface
ectoderm (future skin) to detach from the
neuroectoderm and meninges that envelop it. As a
result, the meninges are continuous with a narrow
channel that extends to a dimple in the skin of the
sacral region of the back.
• The dimple indicates the region of closure of the
caudal neuropore at the end of the fourth week and
therefore represents the last place of separation
between the surface ectoderm and the neural tube.
SPINA BIFIDA OCCULTA
•Spina bifida occulta is an NTD resulting from
failure of the halves of one or more neural
arches to fuse in the median plane
•This NTD occurs in the L5 or S1 vertebra in
approximately 10% of otherwise normal
people.
• In the minor form, the only evidence of its
presence may be a small dimple with a tuft of
hair arising from it .
•Spina bifida occulta usually produces no
symptoms.
• A few affected infants have functionally
significant defects of the underlying spinal
cord and dorsal roots
SPINA BIFIDA CYSTICA
• These are the severe types of spina bifida, which involve
protrusion of the spinal cord and/or meninges through
defects in the vertebral arches.
• The spinal cord and spinal roots are in the normal position,
but there may be spinal cord defects.
• If the spinal cord or nerve roots are contained within the
meningeal cyst, the defect is spina bifida with
meningomyelocele.
• Severe cases involving several vertebrae are associated
with absence of the calvaria (skullcap), absence of most of
the brain, and facial abnormalities; these severe defects
are called meroencephaly, for these neonates, death is
inevitable.
• Spina bifida cystica shows various degrees of neurologic
deficit, depending on the position and extent of the lesion.
SPINAL BIFIDA CYSTICA
• Sphincter paralysis (bladder or anal sphincters) is
common with lumbosacral meningomyelocele.
• Meroencephaly is strongly suspected in utero when
there is a high level of alpha fetoprotein (AFP) in the
amniotic fluid
• The level of AFP may also be elevated in maternal
blood serum. Amniocentesis is usually performed on
pregnant women with high levels of serum AFP for the
determination of the AFP level in the amniotic fluid.
• An ultrasound scan may reveal an NTD that has
resulted in spina bifida cystica.
• The fetal vertebral column can be detected by
ultrasound at 10 to 12 weeks, and if there is a defect
in the vertebral arch, a meningeal cyst may be
detected in the affected area .
MYELOSCHISIS
•Myeloschisis is the most severe type of spina
bifida.
• In this defect, the spinal cord in the affected
area is open because the neural folds failed to
fuse.
•As a result, the spinal cord is represented by a
flattened mass of nervous tissue.
•Myeloschisis usually results in permanent
paralysis or weakness of the lower limbs.
SPINA BIFIDA CYSTICA
Spina bifida with meningomyelocele
Spina bifida within lumbar region
myeloschisis
SPINA BIFIDA
•The infants with
Spina Bifida complain
from :
•Paralyzed, anesthetic
lower limbs.
•Incontinence of urine
and stool.
MENINGIOMYELOCELE
•It is Spina Bifida with
•The appearance of the
meninges of the spinal
cord on the back of
the body.
CAUSES OF NEURAL TUBE DEFECTS
•Nutritional and environmental factors
undoubtedly play a role in the production of
NTDs.
•Gene-gene and gene-environment interactions
are likely involved in most cases.
•Food fortification with folic acid and folic acid
supplements taken before conception and
continued for at least 3 months during
pregnancy reduce the incidence of NTDs.
CONTINUE………
•In 2015, the Centers for Disease Control and
Prevention urged “all women of childbearing
age who can become pregnant to get 0.4 mg
of folic acid every day to help reduce the risk
of neural tube defects.
• Epidemiologic studies have also shown that
low maternal B12 levels may significantly
increase the risk of NTDs.
•Certain drugs (e.g., valproic acid) increase the
risk of meningomyelocele. This anticonvulsant
drug causes NTDs in 1% to 2% of pregnancies if
taken during early pregnancy, when the neural
folds are fusing.
BRAIN
•In the 5th week of development, the swellings
appear at the cranial end of the neural tube.
Three primitive vesicles appears first, and
subsequently they develop into five secondary
vesicles.
•These vesicles will give rise to all the
structures of the brain and cerebellum, as well
as the ventricular system.
•Meanwhile, the neuroderm cells begin to
differentiate into neurons and glial cells.
•Neurons migrate throughout the brain, and
once they have reached their final destination
they develop axons and dendrites, forming
synapses.
DIFFERENTIATION OF BRAIN
•5th week:
•Three primary brain
vesicles appear :
•Fore brain
(Prosencephalon).
•Mid brain
(Mesencephalon).
•Hind brain
(Rombencephalon).
FLEXURES
•The neuroaxis is bent
by two flexures :
•Cephalic ( Mid brain)
flexure at the
junction of the fore
and mid brains.
•Cervical flexure :
•Between the brain
and spinal cord.
SEVENTH WEEK
• Five secondary brain vesicles
appear.
PROSENCEPHALON
• Is divided into :
• Telencephalon.
• Diencephalon.
TELENCEPHALON
• It is the largest brain
vesicle.
• It has the greatest degree
of development.
• It forms the two Cerebral
Hemispheres.
DIENCEPHALON
•It is formed mainly
of the Thalamus.
•The Thalamus
contains numerous
groups of neurons
and is connected
with the cerebral
cortex.
ROMBENCEPHALON
•Is divided into :
•Metencephalon.
•Mylencephalon.
PONTINE FLEXURE
•It is the third flexure
that appears between
the metencephalon
and the
myelencephalon.
METENCEPHALON
•It is
differentiated
into:
•Pons .
•Cerebellum.
MYELENCEPHALON
• It will form :
• The Medulla Oblongata.
MESENCEPHALON
•It remains
undifferentiated.
•It is in the form of its
embryonic picture :
•Central canal
surrounded by grey
matter.
BRAIN CENTERS
• They consist of :
• Bilateral paired centers for
the senses of :
• Smell, Vision, Hearing and
• A symmetrical midline
Vestibular center for the
maintenance of equilibrium.
BRAIN CENTERS
•They start to appear
as expansions from the
dorsal aspect of the
simple tubular brain.
•They are composed of
an outer cortex of
nerve cells with
underlying core of
nerve fibers.
BRAIN CENTERS
•The centers for vision and
hearing will form largely
automatic, reflex functions.
•They are represented by the
four colliculi (superior &
inferior).
•The motor center near the
caudal end of the brain will
be in the cerebellum.
PROSENCEPHALISATION
•The massive cerebral
hemispheres which are
developed from the
rostral (olfactory) part of
the brain take an
executive role in many
functions of the brain.
PROSENCEPHALISATION
•They become the highest
levels for perception and
correlation of all sensory
modalities
•They are the highest level
for motor control.
•The other centers become
progressively subservient to
the cerebral hemispheres.
BIRTH DEFECTS OF BRAIN
• Because of the complexity of its embryologic history,
abnormal development of the brain is common
(approximately 3 of 1000 births).
• Most major birth defects, such as meroencephaly and
meningoencephalocele, result from defective closure
of the rostral neuropore (an NTD) during the fourth
week and involve the overlying tissues (meninges and
calvaria).
• The factors causing NTDs are genetic, nutritional, and
environmental.
• Birth defects of the brain can be caused by alterations
in the morphogenesis or histogenesis of the nervous
tissue, or they can result from developmental failures
occurring in associated structures(notochord, somites,
mesenchyme, and cranium)
CONTINUE…..
• Abnormal histogenesis of the cerebral cortex can
result in seizures and various degrees of mental
deficiency.
• Subnormal intellectual development may result from
exposure of the embryo or fetus during the 8- to 16-
week period to viruses such as Rubella virus and high
levels of radiation
• Prenatal risk factors, such as maternal infection or
thyroid disorder, Rh factor incompatibility, and some
hereditary and genetic conditions, but the deficit may
result from events during birth.
CONGENITAL ANOMALIES
•(1) Anencephaly
•The brain and skull
are minute.
•It is incompatible for
life.
ENCEPHALOCELE
• Encephalocele is a herniation
of intracranial contents
resulting from a defect in the
cranium (cranium bifidum).
• Encephaloceles are most
common in the occipital
region.
• The hernia may contain
meninges (meningocele),
meninges and part of the brain
(meningoencephalocele), or
meninges, part of the brain,
and part of the ventricular
system
(meningohydroencephalocele).
• Encephalocele occurs in
approximately 1 of 2000
births.
Hydrocephalus
• From Greek hydrokephalos,
from hydr- + kephalE head
• 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
Introduction
• Significant enlargement of the
head results from an imbalance
between the production and
absorption of CSF; as a result,
there is an excess of CSF in the
ventricular system of the brain
• Hydrocephalus results from
impaired circulation and
absorption of CSF and, in rare
cases, from increased
production of CSF by a choroid
plexus adenoma (benign
tumor).
• A premature infant may develop
intraventricular hemorrhage
leading to hydrocephalus
through the obstruction of the
lateral aperture (foramen of
Luschka) and median aperture
(foramen of Magendie).
• Rarely, impaired CSF circulation
results from congenital
aqueductal stenosis the cerebral
aqueduct is narrow or consists
of several minute channels
Introduction
• In a few cases, stenosis results
from transmission of an X-linked
recessive trait, but most cases
appear to result from a fetal
viral infection (e.g.,
cytomegalovirus) or Toxoplasma
gondii.
• Blockage of CSF circulation
results in dilation of the
ventricles proximal to the
obstruction, internal
accumulation of CSF, and
pressure on the cerebral
hemispheres.
• This squeezes the brain
between the ventricular fluid
and the neurocranium.
• In infants, the internal pressure
results in an accelerated rate of
expansion of the brain and
neurocranium because most of
the fibrous sutures are not
fused.
• Although hydrocephalus may be
associated with spina bifida
cystica, enlargement of the
head may not be obvious at
birth
Overview of CSF production
• The CSF volume of an average
adult ranges from 80 to 160 ml
• The ventricular system holds
approximately 20 to 50 ml of
CSF
• CSF is produced in the choroid
plexuses at a daily rate of 14-36
ml/hr
Overview of CSF production
•The choroid
plexuses are the
source of
approximately 80%
of the CSF
•The blood vessels in
the subependymal
regions, and pia also
contribute to the
formation of CSF
Overview of CSF circulation
• The CSF flows from the
lateral ventricles downward
to the foramina of
Magendie and Luschka, to
the perimedullary and
perispinal subarachnoid
spaces, and then upward to
the basal cistern and finally
to the superior and lateral
surfaces of the cerebral
hemispheres
CSF circulation
• The pressure gradient is
highest in the lateral
ventricles and diminishes
successively along the
subarachnoid space
• Arterial pulsations in the
choroid plexuses help drive
the fluid from the
ventricular system
• Normally, the
periventricular tissues offer
little resistance to the flow
of CSF
+
-
CSF pressure
• The CSF volume and pressure
are maintained on a minute to
minute basis by the systemic
circulation
• CSF pressure is in equilibrium
with capillary pressure
(determined by the arteriolar
tone)
• An increase in blood PCO2
(hypoventilation) decreases pH
and arteriolar resistance, this in
turn gives rise to increased CSF
pressure by increasing cerebral
blood flow
• Hyperventilation has the
opposite effect
CSF pressure
• Normal intracranial pressure
(ICP) in an adult is between 2-8
mmHg.
• Levels up to 16 mmHg are
considered normal
• ICP higher than 40 mmHg or
lower BP may combine to cause
ischemic damage
CSF pressure
• Increased venous pressure has
a direct effect on CSF pressure
• Downstream block of venous
flow increases the volume of
cerebral veins, dural sinuses,
and the subarachnoid space
The function of the CSF
• The CSF acts as a “water jacket”
for the brain and spinal cord
• The 1300 g adult brain weighs
approximately 45 g when
suspended in CSF
The function of the CSF
• The CSF acts like a “sink”,
effectively flushing waste
products as new fluid is
secreted reabsorbed
• A constant CSF electrolyte
composition helps maintain a
stable medium for excitable
cells (neurons)
Mechanisms of increase intracranial pressure
• Brain, Blood and CSF are held in
an inelastic container
(cranium, vertebral canal and
dura)
• Changes in volume of either
element (Brain,CSF, Blood) is at
the expense of the other two
Hydrocephalus
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 space
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
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.
Aqueductal stenosis
• The normal aqueduct measures
about 1 mm in diameter, and is
about 11 mm in length.
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
Etiology of aqueductal stenosis
• Intrinsic Pathology of the Aqueduct
• Septum or Membrane Formation: A thin membrane of neuroglia may occlude
the aqueduct. It commonly occurs caudally. There may be a primary
developmental defect or it may follow granular ependymitis from intrauterine
infections. This is the rarest of the types of narrowing.
• Forking of the Aqueduct:Typically, there are two channels seen in midsagittal
plane unable to handle CSF volume. Most often seen with spina bifida.
• Gliosis of the Aqueduct: Usually of infectious origin showing a marked
gliofibrillary response. The lumen is devoid of ependyma.
• Stenosis of the Aqueduct: Narrowed aqueduct without evidence of gliosis. This
may have hereditary basis.
Etiology of aqueductal stenosis
• Extrinsic Pathology of the Aqueduct:
• Infectious. Abscesses.
• Neoplastic. Pineal tumors, brainstem gliomas, medulloblastoma,
ependymoma.
• Vascular. AVM, aneurysm, Galen aneurysm.
• Developmental. Arachnoid cysts.
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
Imaging of aqueductal stenosis
• Ultrasonography can detect
aqueductal stenosis in utero.
Sonogram
Imaging of aqueductal stenosis
• CT and MRI. MRI is essential if
third ventriculostomy is to be
considered.
Treatment of aqueductal stenosis
• Treatment and Results
• Remove underlying cause of
obstruction if possible.
• Third ventriculostomy as initial
treatment of choice.
• VP shunt if technical reasons do not
allow third ventriculostomy or if the
child fails after ventriculostomy.
• Aqueductal stent can be placed if
technically feasible. Usually rarely
done due to risk of upper brain stem
injury.
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.
• Usually there is an obliteration of the subarachnoid cisterns or
malfunction of the arachnoid villi.
Causes of communicating hydrocephalus
• Overproduction of CSF
• Blockage of CSF circulation
• Blockage of CSF resorption
• Hydrocephalus ex-vacuo
• Normal pressure hydrocephalus
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.
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.
Dandy Walker Syndrome
• A common cause of
obstructive hydrocephalus
is Dandy Walker Syndrome
where there is blockage of
foramina of the 4th
ventricle. This is a
congenital condition
associated with agenesis of
the cerebellar vermis
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
Hydrocephalus Ex Vacuo
• Hydrocephalus ex-vacuo involves
the presence of too much CSF,
although the CSF pressure itself
is normal. This condition occurs
when there is damage to the
brain caused by stroke or other
form of injury or chronic
neurodegeneration, and there
may be an actual shrinkage of
brain substance.
Normal pressure hydrocephalus
• Normal pressure hydrocephalus
(NPH) is usually due to a gradual
blockage of the CSF drainage
pathways in the brain. NPH is an
unusual cause of dementia,
which can occur as a
complication of brain infection or
bleeding (hemorrhage).
Normal pressure hydrocephalus
• In some patients, no predisposing
cause can be identified.
• In patients with NPH, although
the ventricles enlarge, the
pressure of the CSF remains
within normal range.
• NPH is characterized by gradual
memory loss (dementia), balance
disorder (ataxia), urine
incontinence, and a general
slowing of activity.
• Symptoms progressively worsen
over weeks. In some patients, an
improvement of symptoms is
noted immediately after the
removal of spinal fluid with a
lumbar procedure.
Treatment of hydrocephalus
• The two most commonly used
shunt systems are the
ventriculoatrial (VA) and
ventriculoperitoneal (VP) shunts.
The VP shunt is most commonly
used as it is simpler to place,
extra tubing may be placed in the
peritoneum and the
consequences of infection are
less.
Treatment of hydrocephalus
• The VA shunt must be accurately
located in the atrium and
requires frequent revisions as
the child grows to maintain the
proper position of the distal end.
In addition, infection is a more
serious complication with a VA
shunt as its location in the blood
stream may lead to sepsis.
Treatment of hydrocephalus
• Recently, in situations where both
the abdomen and vascular system
can no longer function to absorb
CSF, Pediatric Neurosurgeons have
begun to place the distal catheter
in the pleural space (V-PL shunt).
The distal catheter is placed
through a small incision in the
anterior chest wall. As with the
peritoneal shunt, extra tubing can
be placed, reducing the need for
further shunt revisions.
•
Treatment of hydrocephalus
• Shunt systems include three
components: (1) a ventricular
catheter, (2) a one way valve and
(3) a distal catheter. The
ventricular catheter is a straight
piece of tubing, closed on the
proximal end and usually with
multiple holes for the entry of
CSF along the proximal two
centimeters of the tube.
Treatment of hydrocephalus
• Shunts are composed of a
material called Silastic. Silastic is
made from a family of
polymerized organic compounds
termed silicone. Silicone is the
substance that has caused
controversy in breast implants
because of the association with
auto immune disorders. So far no
cases of auto immune disease
have been linked to the Silastic
used in shunts.
Treatment of hydrocephalus
• The most common sites for entry
of the ventricular catheter are a
frontal position in line with the
pupil at the coronal suture, a
parietal position just above and
behind the ear, or an occipital
position three centimeters off
the posterior midline. The
position used varies with the
configuration of the ventricles,
the shape and size of the head
and the surgeon’s preference.
Shunt malfunction
• Common complications of VP shunt include shunt malfunction or
blockage and infection. Malfunction may be related to growth and
the shunt will need to be replaced with a longer catheter. Symptoms
of shunt malfunction or infection include headache, fever,
drowsiness,convulsions, increased head circumference and bulging
fontanelle.
Shunt malfunction
• If left untreated, shunt malfunction or infection is
associated with high morbidity and mortality rates. Most
patients with these complications have subtle presentations
and nonspecific signs, despite elevated ICP or CNS infection.
The workup includes a focused review of records,
information from the patient’s family or caretaker, and
elements of a unique examination to supplement routine
work-up of the patient with a ventricular shunt. A shunt
series and head CT scan are part of the initial evaluation.
Empiric antibiotic therapy is initiated to cover Gram-
positive organisms, predominantly S. epidermidis, as well as
the less common Gram-negative and anaerobic organisms
responsible for shunt infections.

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KCMC Surgical NEUROTUBE DEFECTS_101932.ppt

  • 1. CNS DEVELOPMENT Presenter: Justine D. Ngwanda Supervisor: Dr. H. Rabiel KCMU College Surgical Department
  • 2. INTRODUCTION •The central nervous system (CNS) consists of the brain and spinal cord and is protected by the cranium and vertebral column. •At the end of week two, a structure called the Primitive streak appears as a groove in the epiblast layer of the bilaminar disk. •Cells within the epiblast migrate downward through the primitive streak, giving rise to the three layers from the initial two. •These three germinal layers form the trilaminar embryonic disc: Endoderm, Mesoderm and the Ectoderm. •The CNS is derived from the ectoderm, which is the outermost layer of the embryonic disc.
  • 3. SECOND WEEK Differentiation of the embryo into three germ layers : •Ectoderm. •Mesoderm. •Endoderm. •The Ectoderm will form •(1) Central nervous system. •(2) Epidermis of Skin.
  • 4. NEURULATION • In the 3rd week, the notochord appears in the mesoderm, which then secretes growth factor i.e. Sonic hedgehog (SHH), and bone morphogenic proteins (BMPs) which stimulates the differentiation of the underlying ectoderm into Neuroectoderm, forming a structure known as the neural plate. • On lateral edges of the plate, form neural folds, which meet in the midline, fusing to form the Neural tube which is a precursor to the brain and spinal cord. • During fusion of the neural folds, some cells within the folds migrate to form a distinct cell population known as Neural crest. • The neural crest give rise to diverse cell lineage including melanocytes, craniofacial cartilage and bone, smooth muscles, peripheral and enteric neurons and glia. • So, neurulation is the formation of neural tube, which is achieved by the end of 4th week in the region of 4th to 6th somites.
  • 5. • So the first indications of the developing nervous system appear during the third week as the neural plate and neural groove develop on the posterior aspect of the trilaminar embryo. • At this stage, the cranial two thirds of the neural plate and tube as far caudal as the fourth pair of somites represent the future brain, and the caudal one third of the plate and tube represents the future spinal cord. • Fusion of the neural folds and formation of the neural tube begins at the fifth somite and proceeds in cranial and caudal directions until only small areas of the tube remain open at both ends. • The lumen of the neural tube becomes the neural canal, which communicates freely with the amniotic cavity. • The rostral neuropore closes at approximately the 25th day, and the caudal neuropore closes at approximately the 27th day.
  • 6. • Syndecan 4 (SDC4) and van gogh–like 2 (VANGL2) proteins appear to be involved with neural tube closure. • The neuroprogenitor cells of the wall of the neural tube thicken to form the brain and spinal cord. • The neural canal forms the ventricular system of the brain and the central canal of the spinal cord.
  • 7. THIRD WEEK •Neural Plate : •It is a dorsal midline thickening of the ectoderm overlying the notochord (Neuroectoderm) .
  • 8. THIRD WEEK •Neural Folds : •They are the elevated lateral margins of the neural plate. •They are on each side of the longtudinal midline (Neural Groove).
  • 9. NEURAL TUBE •It is formed from the apposition and fusion of the neural folds which seal the neural groove and create the tube.
  • 10. FOURTH WEEK •The neural tube is completed and transformed into the adult CNS. •This growth is maximal at the rostral part which becomes the brain. •The caudal portion becomes the spinal cord. •The axis of the neural tube (neuroaxis) is straight.
  • 11. NEURAL GROOVE •The central cavity within the neural tube becomes : •Ventricles of the brain and •Central canal of the spinal cord.
  • 12. NEURAL CREST • They are separated cells from the apices of the neural folds. • They are dorsolateral to the neural tube. • They give rise to : • Autonomic ganglia. • Sensory ganglia of spinal and cranial nerves. • Melanocytes. • Cells of supra renal medulla.
  • 13. DIFFERENTIATION OF SPINAL CORD •The Grey matter is located centrally around the central canal. •The White matter forms the outer coat.
  • 14. DIFFERENTIATION OF SPINAL CORD • Sulcus Limitans : • It is a longitudinal groove along the inner surface of the lateral walls of the developing spinal cord. • It differentiates the grouping of cells (gray matter),cells on the dorsal side form the Alar plate, which becomes the dorsal horn (posterior) and cells at the ventral end form the Basal plate, which then becomes the ventral horn ( Anterior).
  • 15. DIFFERENTIATION OF SPINAL CORD •The Alar plate is predominantly sensory in function. •The Basal plate is predominantly motor in function.
  • 16. BIRTH DEFECTS OF SPINAL CORD • Most defects result from failure of fusion of one or more neural arches of the developing vertebrae during the fourth week. • NTDs affect the tissues overlying the spinal cord: meninges, neural arches, muscles, and skin. • Defects involving the embryonic neural arches are referred to as spina bifida; subtypes of this defect are based on the degree and pattern of the NTD. • The term spina bifida denotes nonfusion of the halves of the embryonic neural arches, which is common to all types of spina bifida . • Spina bifida ranges from clinically significant types to minor defects that are functionally unimportant.
  • 17. DERMAL SINUS • A dermal sinus is lined with epidermis and skin appendages extending from the skin to a deeper-lying structure, usually the spinal cord. • The sinus (channel) is associated with closure of the neural tube and formation of the meninges in the lumbosacral region of the spinal cord. • The birth defect is caused by failure of the surface ectoderm (future skin) to detach from the neuroectoderm and meninges that envelop it. As a result, the meninges are continuous with a narrow channel that extends to a dimple in the skin of the sacral region of the back. • The dimple indicates the region of closure of the caudal neuropore at the end of the fourth week and therefore represents the last place of separation between the surface ectoderm and the neural tube.
  • 18. SPINA BIFIDA OCCULTA •Spina bifida occulta is an NTD resulting from failure of the halves of one or more neural arches to fuse in the median plane •This NTD occurs in the L5 or S1 vertebra in approximately 10% of otherwise normal people. • In the minor form, the only evidence of its presence may be a small dimple with a tuft of hair arising from it . •Spina bifida occulta usually produces no symptoms. • A few affected infants have functionally significant defects of the underlying spinal cord and dorsal roots
  • 19. SPINA BIFIDA CYSTICA • These are the severe types of spina bifida, which involve protrusion of the spinal cord and/or meninges through defects in the vertebral arches. • The spinal cord and spinal roots are in the normal position, but there may be spinal cord defects. • If the spinal cord or nerve roots are contained within the meningeal cyst, the defect is spina bifida with meningomyelocele. • Severe cases involving several vertebrae are associated with absence of the calvaria (skullcap), absence of most of the brain, and facial abnormalities; these severe defects are called meroencephaly, for these neonates, death is inevitable. • Spina bifida cystica shows various degrees of neurologic deficit, depending on the position and extent of the lesion.
  • 20. SPINAL BIFIDA CYSTICA • Sphincter paralysis (bladder or anal sphincters) is common with lumbosacral meningomyelocele. • Meroencephaly is strongly suspected in utero when there is a high level of alpha fetoprotein (AFP) in the amniotic fluid • The level of AFP may also be elevated in maternal blood serum. Amniocentesis is usually performed on pregnant women with high levels of serum AFP for the determination of the AFP level in the amniotic fluid. • An ultrasound scan may reveal an NTD that has resulted in spina bifida cystica. • The fetal vertebral column can be detected by ultrasound at 10 to 12 weeks, and if there is a defect in the vertebral arch, a meningeal cyst may be detected in the affected area .
  • 21. MYELOSCHISIS •Myeloschisis is the most severe type of spina bifida. • In this defect, the spinal cord in the affected area is open because the neural folds failed to fuse. •As a result, the spinal cord is represented by a flattened mass of nervous tissue. •Myeloschisis usually results in permanent paralysis or weakness of the lower limbs.
  • 22. SPINA BIFIDA CYSTICA Spina bifida with meningomyelocele Spina bifida within lumbar region myeloschisis
  • 23. SPINA BIFIDA •The infants with Spina Bifida complain from : •Paralyzed, anesthetic lower limbs. •Incontinence of urine and stool.
  • 24. MENINGIOMYELOCELE •It is Spina Bifida with •The appearance of the meninges of the spinal cord on the back of the body.
  • 25. CAUSES OF NEURAL TUBE DEFECTS •Nutritional and environmental factors undoubtedly play a role in the production of NTDs. •Gene-gene and gene-environment interactions are likely involved in most cases. •Food fortification with folic acid and folic acid supplements taken before conception and continued for at least 3 months during pregnancy reduce the incidence of NTDs.
  • 26. CONTINUE……… •In 2015, the Centers for Disease Control and Prevention urged “all women of childbearing age who can become pregnant to get 0.4 mg of folic acid every day to help reduce the risk of neural tube defects. • Epidemiologic studies have also shown that low maternal B12 levels may significantly increase the risk of NTDs. •Certain drugs (e.g., valproic acid) increase the risk of meningomyelocele. This anticonvulsant drug causes NTDs in 1% to 2% of pregnancies if taken during early pregnancy, when the neural folds are fusing.
  • 27. BRAIN •In the 5th week of development, the swellings appear at the cranial end of the neural tube. Three primitive vesicles appears first, and subsequently they develop into five secondary vesicles. •These vesicles will give rise to all the structures of the brain and cerebellum, as well as the ventricular system. •Meanwhile, the neuroderm cells begin to differentiate into neurons and glial cells. •Neurons migrate throughout the brain, and once they have reached their final destination they develop axons and dendrites, forming synapses.
  • 28. DIFFERENTIATION OF BRAIN •5th week: •Three primary brain vesicles appear : •Fore brain (Prosencephalon). •Mid brain (Mesencephalon). •Hind brain (Rombencephalon).
  • 29. FLEXURES •The neuroaxis is bent by two flexures : •Cephalic ( Mid brain) flexure at the junction of the fore and mid brains. •Cervical flexure : •Between the brain and spinal cord.
  • 30. SEVENTH WEEK • Five secondary brain vesicles appear.
  • 31. PROSENCEPHALON • Is divided into : • Telencephalon. • Diencephalon.
  • 32. TELENCEPHALON • It is the largest brain vesicle. • It has the greatest degree of development. • It forms the two Cerebral Hemispheres.
  • 33. DIENCEPHALON •It is formed mainly of the Thalamus. •The Thalamus contains numerous groups of neurons and is connected with the cerebral cortex.
  • 34. ROMBENCEPHALON •Is divided into : •Metencephalon. •Mylencephalon.
  • 35. PONTINE FLEXURE •It is the third flexure that appears between the metencephalon and the myelencephalon.
  • 37. MYELENCEPHALON • It will form : • The Medulla Oblongata.
  • 38. MESENCEPHALON •It remains undifferentiated. •It is in the form of its embryonic picture : •Central canal surrounded by grey matter.
  • 39. BRAIN CENTERS • They consist of : • Bilateral paired centers for the senses of : • Smell, Vision, Hearing and • A symmetrical midline Vestibular center for the maintenance of equilibrium.
  • 40. BRAIN CENTERS •They start to appear as expansions from the dorsal aspect of the simple tubular brain. •They are composed of an outer cortex of nerve cells with underlying core of nerve fibers.
  • 41. BRAIN CENTERS •The centers for vision and hearing will form largely automatic, reflex functions. •They are represented by the four colliculi (superior & inferior). •The motor center near the caudal end of the brain will be in the cerebellum.
  • 42. PROSENCEPHALISATION •The massive cerebral hemispheres which are developed from the rostral (olfactory) part of the brain take an executive role in many functions of the brain.
  • 43. PROSENCEPHALISATION •They become the highest levels for perception and correlation of all sensory modalities •They are the highest level for motor control. •The other centers become progressively subservient to the cerebral hemispheres.
  • 44. BIRTH DEFECTS OF BRAIN • Because of the complexity of its embryologic history, abnormal development of the brain is common (approximately 3 of 1000 births). • Most major birth defects, such as meroencephaly and meningoencephalocele, result from defective closure of the rostral neuropore (an NTD) during the fourth week and involve the overlying tissues (meninges and calvaria). • The factors causing NTDs are genetic, nutritional, and environmental. • Birth defects of the brain can be caused by alterations in the morphogenesis or histogenesis of the nervous tissue, or they can result from developmental failures occurring in associated structures(notochord, somites, mesenchyme, and cranium)
  • 45. CONTINUE….. • Abnormal histogenesis of the cerebral cortex can result in seizures and various degrees of mental deficiency. • Subnormal intellectual development may result from exposure of the embryo or fetus during the 8- to 16- week period to viruses such as Rubella virus and high levels of radiation • Prenatal risk factors, such as maternal infection or thyroid disorder, Rh factor incompatibility, and some hereditary and genetic conditions, but the deficit may result from events during birth.
  • 46. CONGENITAL ANOMALIES •(1) Anencephaly •The brain and skull are minute. •It is incompatible for life.
  • 47. ENCEPHALOCELE • Encephalocele is a herniation of intracranial contents resulting from a defect in the cranium (cranium bifidum). • Encephaloceles are most common in the occipital region. • The hernia may contain meninges (meningocele), meninges and part of the brain (meningoencephalocele), or meninges, part of the brain, and part of the ventricular system (meningohydroencephalocele). • Encephalocele occurs in approximately 1 of 2000 births.
  • 48. Hydrocephalus • From Greek hydrokephalos, from hydr- + kephalE head • 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
  • 49. Introduction • Significant enlargement of the head results from an imbalance between the production and absorption of CSF; as a result, there is an excess of CSF in the ventricular system of the brain • Hydrocephalus results from impaired circulation and absorption of CSF and, in rare cases, from increased production of CSF by a choroid plexus adenoma (benign tumor). • A premature infant may develop intraventricular hemorrhage leading to hydrocephalus through the obstruction of the lateral aperture (foramen of Luschka) and median aperture (foramen of Magendie). • Rarely, impaired CSF circulation results from congenital aqueductal stenosis the cerebral aqueduct is narrow or consists of several minute channels
  • 50. Introduction • In a few cases, stenosis results from transmission of an X-linked recessive trait, but most cases appear to result from a fetal viral infection (e.g., cytomegalovirus) or Toxoplasma gondii. • Blockage of CSF circulation results in dilation of the ventricles proximal to the obstruction, internal accumulation of CSF, and pressure on the cerebral hemispheres. • This squeezes the brain between the ventricular fluid and the neurocranium. • In infants, the internal pressure results in an accelerated rate of expansion of the brain and neurocranium because most of the fibrous sutures are not fused. • Although hydrocephalus may be associated with spina bifida cystica, enlargement of the head may not be obvious at birth
  • 51. Overview of CSF production • The CSF volume of an average adult ranges from 80 to 160 ml • The ventricular system holds approximately 20 to 50 ml of CSF • CSF is produced in the choroid plexuses at a daily rate of 14-36 ml/hr
  • 52. Overview of CSF production •The choroid plexuses are the source of approximately 80% of the CSF •The blood vessels in the subependymal regions, and pia also contribute to the formation of CSF
  • 53. Overview of CSF circulation • The CSF flows from the lateral ventricles downward to the foramina of Magendie and Luschka, to the perimedullary and perispinal subarachnoid spaces, and then upward to the basal cistern and finally to the superior and lateral surfaces of the cerebral hemispheres
  • 54. CSF circulation • The pressure gradient is highest in the lateral ventricles and diminishes successively along the subarachnoid space • Arterial pulsations in the choroid plexuses help drive the fluid from the ventricular system • Normally, the periventricular tissues offer little resistance to the flow of CSF + -
  • 55. CSF pressure • The CSF volume and pressure are maintained on a minute to minute basis by the systemic circulation • CSF pressure is in equilibrium with capillary pressure (determined by the arteriolar tone) • An increase in blood PCO2 (hypoventilation) decreases pH and arteriolar resistance, this in turn gives rise to increased CSF pressure by increasing cerebral blood flow • Hyperventilation has the opposite effect
  • 56. CSF pressure • Normal intracranial pressure (ICP) in an adult is between 2-8 mmHg. • Levels up to 16 mmHg are considered normal • ICP higher than 40 mmHg or lower BP may combine to cause ischemic damage
  • 57. CSF pressure • Increased venous pressure has a direct effect on CSF pressure • Downstream block of venous flow increases the volume of cerebral veins, dural sinuses, and the subarachnoid space
  • 58. The function of the CSF • The CSF acts as a “water jacket” for the brain and spinal cord • The 1300 g adult brain weighs approximately 45 g when suspended in CSF
  • 59. The function of the CSF • The CSF acts like a “sink”, effectively flushing waste products as new fluid is secreted reabsorbed • A constant CSF electrolyte composition helps maintain a stable medium for excitable cells (neurons)
  • 60. Mechanisms of increase intracranial pressure • Brain, Blood and CSF are held in an inelastic container (cranium, vertebral canal and dura) • Changes in volume of either element (Brain,CSF, Blood) is at the expense of the other two
  • 61. Hydrocephalus 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 space
  • 62. 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
  • 63. 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.
  • 64. Aqueductal stenosis • The normal aqueduct measures about 1 mm in diameter, and is about 11 mm in length.
  • 65. 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
  • 66. Etiology of aqueductal stenosis • Intrinsic Pathology of the Aqueduct • Septum or Membrane Formation: A thin membrane of neuroglia may occlude the aqueduct. It commonly occurs caudally. There may be a primary developmental defect or it may follow granular ependymitis from intrauterine infections. This is the rarest of the types of narrowing. • Forking of the Aqueduct:Typically, there are two channels seen in midsagittal plane unable to handle CSF volume. Most often seen with spina bifida. • Gliosis of the Aqueduct: Usually of infectious origin showing a marked gliofibrillary response. The lumen is devoid of ependyma. • Stenosis of the Aqueduct: Narrowed aqueduct without evidence of gliosis. This may have hereditary basis.
  • 67. Etiology of aqueductal stenosis • Extrinsic Pathology of the Aqueduct: • Infectious. Abscesses. • Neoplastic. Pineal tumors, brainstem gliomas, medulloblastoma, ependymoma. • Vascular. AVM, aneurysm, Galen aneurysm. • Developmental. Arachnoid cysts.
  • 68. 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
  • 69. Imaging of aqueductal stenosis • Ultrasonography can detect aqueductal stenosis in utero. Sonogram
  • 70. Imaging of aqueductal stenosis • CT and MRI. MRI is essential if third ventriculostomy is to be considered.
  • 71. Treatment of aqueductal stenosis • Treatment and Results • Remove underlying cause of obstruction if possible. • Third ventriculostomy as initial treatment of choice. • VP shunt if technical reasons do not allow third ventriculostomy or if the child fails after ventriculostomy. • Aqueductal stent can be placed if technically feasible. Usually rarely done due to risk of upper brain stem injury.
  • 72. 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. • Usually there is an obliteration of the subarachnoid cisterns or malfunction of the arachnoid villi.
  • 73. Causes of communicating hydrocephalus • Overproduction of CSF • Blockage of CSF circulation • Blockage of CSF resorption • Hydrocephalus ex-vacuo • Normal pressure hydrocephalus
  • 74. 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.
  • 75. 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.
  • 76. Dandy Walker Syndrome • A common cause of obstructive hydrocephalus is Dandy Walker Syndrome where there is blockage of foramina of the 4th ventricle. This is a congenital condition associated with agenesis of the cerebellar vermis
  • 77. 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
  • 78. Hydrocephalus Ex Vacuo • Hydrocephalus ex-vacuo involves the presence of too much CSF, although the CSF pressure itself is normal. This condition occurs when there is damage to the brain caused by stroke or other form of injury or chronic neurodegeneration, and there may be an actual shrinkage of brain substance.
  • 79. Normal pressure hydrocephalus • Normal pressure hydrocephalus (NPH) is usually due to a gradual blockage of the CSF drainage pathways in the brain. NPH is an unusual cause of dementia, which can occur as a complication of brain infection or bleeding (hemorrhage).
  • 80. Normal pressure hydrocephalus • In some patients, no predisposing cause can be identified. • In patients with NPH, although the ventricles enlarge, the pressure of the CSF remains within normal range. • NPH is characterized by gradual memory loss (dementia), balance disorder (ataxia), urine incontinence, and a general slowing of activity. • Symptoms progressively worsen over weeks. In some patients, an improvement of symptoms is noted immediately after the removal of spinal fluid with a lumbar procedure.
  • 81. Treatment of hydrocephalus • The two most commonly used shunt systems are the ventriculoatrial (VA) and ventriculoperitoneal (VP) shunts. The VP shunt is most commonly used as it is simpler to place, extra tubing may be placed in the peritoneum and the consequences of infection are less.
  • 82. Treatment of hydrocephalus • The VA shunt must be accurately located in the atrium and requires frequent revisions as the child grows to maintain the proper position of the distal end. In addition, infection is a more serious complication with a VA shunt as its location in the blood stream may lead to sepsis.
  • 83. Treatment of hydrocephalus • Recently, in situations where both the abdomen and vascular system can no longer function to absorb CSF, Pediatric Neurosurgeons have begun to place the distal catheter in the pleural space (V-PL shunt). The distal catheter is placed through a small incision in the anterior chest wall. As with the peritoneal shunt, extra tubing can be placed, reducing the need for further shunt revisions. •
  • 84. Treatment of hydrocephalus • Shunt systems include three components: (1) a ventricular catheter, (2) a one way valve and (3) a distal catheter. The ventricular catheter is a straight piece of tubing, closed on the proximal end and usually with multiple holes for the entry of CSF along the proximal two centimeters of the tube.
  • 85. Treatment of hydrocephalus • Shunts are composed of a material called Silastic. Silastic is made from a family of polymerized organic compounds termed silicone. Silicone is the substance that has caused controversy in breast implants because of the association with auto immune disorders. So far no cases of auto immune disease have been linked to the Silastic used in shunts.
  • 86. Treatment of hydrocephalus • The most common sites for entry of the ventricular catheter are a frontal position in line with the pupil at the coronal suture, a parietal position just above and behind the ear, or an occipital position three centimeters off the posterior midline. The position used varies with the configuration of the ventricles, the shape and size of the head and the surgeon’s preference.
  • 87. Shunt malfunction • Common complications of VP shunt include shunt malfunction or blockage and infection. Malfunction may be related to growth and the shunt will need to be replaced with a longer catheter. Symptoms of shunt malfunction or infection include headache, fever, drowsiness,convulsions, increased head circumference and bulging fontanelle.
  • 88. Shunt malfunction • If left untreated, shunt malfunction or infection is associated with high morbidity and mortality rates. Most patients with these complications have subtle presentations and nonspecific signs, despite elevated ICP or CNS infection. The workup includes a focused review of records, information from the patient’s family or caretaker, and elements of a unique examination to supplement routine work-up of the patient with a ventricular shunt. A shunt series and head CT scan are part of the initial evaluation. Empiric antibiotic therapy is initiated to cover Gram- positive organisms, predominantly S. epidermidis, as well as the less common Gram-negative and anaerobic organisms responsible for shunt infections.