Transcript File

CNS DISORDERS CONT….
Dr Shreedhar Paudel
May, 2009
Hydrocephalus
• Increased amount of CSF in the ventricles of
the brain
• Increase CSF pressure
• Ventricular dilatation
• Due to imbalance between production and
absorption of CSF
Hydrocephalus….
• CSF physiology
– Secreted at the choroid plexus of the ventricles
– Absorbed at arachnoid villi and channeled into the
venous circulation
– 720 ml CSF is secreted in a day
CSF Circulation
• It is produced in the brain by modified ependymal cells in
the choroid plexus (approx. 50-70%),
• The remainder is formed around blood vessels and along
ventricular walls
• It circulates from the choroid plexus through the
interventricular foramina (foramen of Monro) into the
third ventricle,
• Then through the cerebral aqueduct (aqueduct of Sylvius)
into the fourth ventricle, where it exits through two lateral
apertures (foramina of Luschka) and one median aperture
(foramen of Magendie)
• It then flows through the cerebellomedullary cistern down
the spinal cord and over the cerebral hemispheres.
CSF Circulation..
• Traditionally, it has been thought that CSF
returns to the vascular system by entering the
dural venous sinuses via the arachnoid
granulations/villi. However, there is suggestion
that the CSF flow along the cranial nerves and
spinal nerve roots allow it into the lymphatic
channels; this flow may play a substantial role
in CSF reabsorbtion, particularly in the
neonate, in which arachnoid granulations are
sparsely distributed.
Hydrocephalus…
• Types
– Communicating Hydrocephalus
• No blockage in the CSF flow
– Non-communicating Hydrocephalus
• Blockage of CSF flow
• Commonly at the level of aqueduct or foramina of
Luschaka and Magendie
Hydrocephalus…
• Causes
– Congenital Hydrocephalus
• Intrauterine infection of TORCH
• Intraventricular hemorrhage
• Congenital malformations like
–Aqueductal stenosis
–Dandy-Walker syndrome
–Arnold-Chiari syndrome
Dandy-Walker malformation
• Characterized by
– Agenesis or hypoplasia of the cerebellar vermis,
– Cystic dilatation of the fourth ventricle,
– Enlargement of the posterior fossa.
– Approximately 70-90% of patients have
hydrocephalus, which often develops postnatally
– Dandy-Walker malformation may be associated
with atresia of the foramen of Magendie and,
possibly, the foramen of Luschka
Arnold-Chiari Syndrome
• A downward displacement of the cerebellar
tonsils and the medulla through the foramen
magnum.
• Portions of cerebellum and brain stem
herniate into cervical spinal canal
Types of Arnold-Chiari Malformation
• Type I: generally asymptomatic during childhood, but
often manifests with headaches and cerebellar
symptoms.
• Type II: usually accompanied by a myelomeningocele
leading to partial or complete paralysis below the
spinal defect. Abnormal development of the cerebellar
vermis and medulla occur, and they both descend into
the foramen magnum. Hydrocephalus is also nearly
always present.
• Type III causes severe neurological defects. It is
associated with an encephalocele
• Type IV involves a failure of brain development
Hydrocephalus….
• Causes…
– Acquired Hydrocephalus
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Pyogenic meningitis
Tuberculosis
Post intra-ventricular hemorrhage
Posterior fossa tumors : medulloblastoma,
astrocytoma, ependymoma
• Intracranial/intraventricular hemorrhage
Hydrocephalus….
• Hydrocephalus Ex Vacuo
– also called normal pressure hydrocephalus
– Ventricular dilatation due to cerebral atrophy
– No increase in CSF pressure
Clinical features
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Inappropriate enlargement of head size
Delayed closure of fontanel and sutures
Prominent forehead
Prominent scalp veins
Sunset sign in eyes
Signs and symptoms of raised ICP
Personality and behavioral changes
Hydrocephalus….
• Diagnosis
– Serial measurement of head circumference
(An increase in head circumference more than
cm in every 2 weeks in first 3 months of lifediagnostic)
-USG head
-CT/ MRI of head
1
Differential diagnosis of large head
• Megalencephaly: Hurler’s syndrome,
metachromatic leukodystrophy, Tay Sach’s
disease
– No signs of raised ICP
– Ventricles are not enlarged
– Normal CSF pressure
• Chronic subdural hematoma
• Familial macrocephaly
Treatment of Hydrocephalus
• General nursing care
• Medical management to decrease CSF volume
and CSF pressure : Acetazolamide, oral
Glycerol
• Management of raised ICP
• Treatment of the cause
• Surgical treatment : ventriculo-peritoneal
shunt, removal of the cause of obstruction
Neural Tube Defects
Congenital structural anomalies
characterized by failure of proper
closure of neural tube and covering
mesoderm and ectoderm
Neural Tube Defects
• Very common structural congenital anomaly
• Incidence is 1.5 per 1,000 live births
• Risk in second sibling is 5 per live 100 births
Neural Tube Defects
• Etiology
– Decreased maternal folate intake
– Multifactorial inheritance
– Other maternal risk factors including alcohol,
radiation exposure, DM, Valproate,
Carbamazepine and zinc deficiency
– Chromosomal abnormalities like trisomy of 13 and
15
Neural Tube Defects
• Clinical features
– Commonest defect is spina bifida
– Others might be anencephaly, encephalocele….
– Defect will be obvious at birth
– Commonly associated with other anomalies
– Lower body paralysis
– Bowel and bladder dysfunction
– Learning disabilities
– Hydrocephalus
Neural Tube Defects (NTD)
• Spina bifida
– Spina bifida occulta: the mildest form of spina
bifida (occulta means hidden). Most children with
this type of defect never have any health
problems, and the spinal cord is often unaffected.
Spina bifida
– Meningocele : involves the meninges, the
membranes responsible for covering and
protecting the brain and spinal cord. If the
meninges push through the hole in the vertebrae,
the sac is called a meningocele.
Spina bifida..
• Myelomeningocele : the most severe form of spina
bifida. It occurs when the meninges push through
the hole in the back, and the spinal cord also pushes
though. Most babies who are born with this type of
spina bifida also have hydrocephalus,
Spina bifida..
• Because of the abnormal development of and
damage to the spinal cord, a child with
myelomeningocele typically has some
paralysis. The degree of paralysis largely
depends on where the opening occurs in the
spine. The higher the opening is on the back,
the more severe the paralysis tends to be.
Diagnosis of NTD
• Prenatal diagnosis
– Alpha fetoprotein level in maternal serum
between 14-16 weeks of pregnancy
– Amniocentesis for alpha fetoprotein level in
amniotic fluid in early pregnancy
– USG of the fetus
Diagnosis of NTD
• Postnatal diagnosis
– USG of head, sac, kidney
– CXR and X-Ray spine
– C/S of the leaking CSF and swab C/S from the
lesion
– Routine investigations
Treatment of NTD
• Multidisciplinary approach
– PEDIATRICIAN
– NEUROLOGIST/ NEUROSURGEON
– UROLOGIST
– ORTHOPEDIC SURGEON
– PHYSIOTHERAPIST
– SOCIAL WORKER
– PSYCHIATRIST
Treatment of NTD
• Decision of treatment depends on
– Degree of paralysis
– Presence of hydrocephalus
– Kyphosis
– Other congenital anomalies
– Evidence of infection of CNS
Treatment of NTD
• Surgery
– EARLY CLOSURE PREVENTS NEUROLOGICAL
DETERIORATION
– OPEN LESION WITH CSF LEAK SHOULD BE CLOSED
WITHIN 24 HOURS
– CLOSED LESION SHOULD BE REPAIRED WITHIN 48
HOURS
– INFECTED LESION SHOULD BE REPAIRED ONLY
AFTER CSF BECOMES STERILE ( should be given
parenteral antibiotics)
Treatment of NTD
• Lorber’s criteria for selective surgery
• Surgery is not done in case of
– Severe paraplegia at or below L3 level
– Kyphosis/ scoliosis
– Gross hydrocephalus
– Associated gross anomalies
– Intracerebral birth injuries
– Neonatal ventriculitis before closure of the back
• 90% would die within the neonatal period
Prevention
• Folic acid supplementation to all pregnant
women– 0.4 mg/ day
• If there is history of previous birth of NTD babies
then 5 mg/ day folic acid
• Counseling of the family with previous child with
NTD
– Risk of recurrence- 3.5% with 1 affected child
– 10% with 2 affected child
– 25% with 3 affected child
• Folate supplementation reduces recurrence risk
by 70%