Hydrocephalus

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Hydrocephalus

• By Dr. Rasha Rashid
• Moderator Dr. Afaf Al-areeny

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Hydrocephalus
Is defined by as a disproportionate
increase in the amount of
CSF within The cranium,
usually in association with
a rise in ICP
that result
from Impaired circulation
and absorption of CSF,
or in the rare
circumstances
From increased production
by a choriod plexus papilloma
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Physiology Circulation of CSF

• The total volume of CSF approximate 50 ml in an
  infant and 150 ml in an adult.

• Probably two thirds or more of this fluid
  originates as a secretion from the choriod
  plexuses in the four ventricles, mainly in the
  two lateral ventricles.

• Additional amounts of fluid are secreted by all
  the ependymal surfaces of the ventricles and the
  arachnoid membranes, and a small amount comes
  from the brain itself through the perivascular
  spaces that surround the blood vessels entering
  the brain.

• Production of CSF in regulated by the hemeostatic
  environment , in response to alterations in CSF
  pressure and neurogenically.

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• The fluid flow from the choriod plexuses and then
  through the CSF System.

• The fluid secreted in the lateral ventricles and
  the third ventricle passes along the aqueduct of
  Sylvius into the forth ventricle, where a small
  amount of additional fluid is added.

• It then passes out of the forth ventricle through
  three small openings, two lateral foramina of
  Luschka and a midline foramin of Magendie,
  entering the cisterna magna, a large fluid space
  that lies behind the medulla and beneath the
  cerebellum.

• The cisterna magna is continuous with the
  subarachnoid space that surrounds the entire
  brain and spinal cord.

• Almost all the CSF then flows upward from the
  cisterna magna through the subarachnoid space
  surrounding the cerebrum.

• From here the fluid flows into multiple
  arachnoidal villi that project into the large
  sagittal venous sinus and other venous sinuses of
  the cerebrum.

• Finally the fluid empties into the venous blood
  through the surfaces of these villi.

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Types of Hydrocephalus

1. Obstructive or non communicating hydrocephalus.
2. Non-obstructive or communicating hydrocephalus.

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Pathophysiology and Etiology

1. Obstructive of non communicating hydrocephalus

• Aqueductal stenosis .

• Aqueductal gliosis.

• Intrauterine viral infections .

• Lesions or malformations of the posterior fossa.

• Vein of Galen malformation.

• Chiari malformation and the Dandy-Walker syndrome.

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2. Nonobstructive or communicating hydrocephalus.

• Most commonly follows a subarachnoid hemorrhage.

• Pnumococcal and tubrculous meningitis .

• Leukemic infiltrates .

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Clinical Manifestations

• The clinical presentation of hydrocephalus is
  variable and depends on many factors, including
• The age at onset.
• The nature of the lesion causing obstruction.
• The duration and rate of rise of the ICP.

The clinical manifestation of hydrocephalus are
caused by ventricular distention and increased
ICP.
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Ventricular distention Dilation of the
lateral ventricles results in stretching of the
Corticopontocerebellar and corticospinal
pathways, which sweep around the lateral margins
of these ventricles to reach the cerebral
peduncles.
ICP Manifestations of increased ICP may evolve
slowly in obstructive hydrocephalus when there is
time for tarnsependymal absorption of CSF to
compensate partially for the obstruction, or they
may evolve acutely when compensation is absent.
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Manifestations According to Age

1. In an infant.

b. In an older child.
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Physical Examination

• Serial measurements of the head circumference
  indicate an increased velocity of growth.

• Pircussion of the skull may produce a
  (cracked-pot) or (Macewen sign), indicating
  separation of the sutures.

• A foreshortened occiput suggests Chiari
  malformation, and a prominent occiput suggests
  the Dandy-Walker malformation.

• Papilledema, abducent nerve palsy, and pyramidal
  tract signs which are most evident in the lower
  extremities are apparent in most cases.

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Chiari Malformation
Consists of two major subgroups

1. Type I

• Produces symptoms during adolescence or
  adult life and is usually not associated with
  hydrocephalus.

• The deformity consists of displacement of the
  cerebellar tonsils into the cervical canal.

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Chiari Malformation
2. Type II

• Is characterized by progressive
  hydrocephalus and a
  myelomeningocele.

• This lesion represents an
  anomaly of the hindbrain,
  probably due to a failure of
  pontine flexure during
  embryogenesis, and result in elongation of
  the forth ventricle and kinking of the brain
  stem, with displacement of the inferior vermis,
  pons, and medulla into the cervical canal.

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The Dandy-Walker Malformation

• Consists of a cystic
  expansion of the forth
  ventrical in the
  posterior
  fossa, which results from
  a developmental
  failure
  of the roof of the forth
  ventrical during
  embryogenesis .

• Approximately 90 of patients have hydrocephalus,
  and a significant number of children have
  associated anomalies, including agenesys of the
  posterior cerebellar vermis and a corpus callosum.

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Diagnosis

• History
• Familial cases .
• Past history.
• Neurofibromatosis.

• Physical examination
• Inspection.
• Palpation.
• Auscultation.

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• Investigation
• Plain skull films.
• CT and MRI.

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Differential Diagnosis

1. The head may appear enlarged secondary to a
   thickened cranium.

2. Chronic subdural collections.
3. Various metabolic and degenerative disorders
of the CNS.
4. Cerebral gigantism and neurofibromatosis.
5. Familial megalencphaly.
6. Hydranencephaly.
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Treatment

• Therapy for hydrocephalus depends on the cause.
• Medical management.
• Surgical management.

Prognosis This depends on the cause
of the dilated ventricles.
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Internal Hydrocephalus Due to an obstruction in
the aqueduct of Monro ,it cannot be shunted and
baby dies
External Hydrocephalus Due to an obstruction in
the aqueduct of Sylvius, it can be shunted.
Hydrocephalus Ex-Vaceu Due to an increase in the
CSF production to compensate the brain atrophy.