Hydrocephalus

Hydrocephalus

Pembimbing : dr. Nick Tobing, Sp. BS

Michelle Husin (2013-061-118)Ellysa Virgiana (2013-061-119)

Cereberospinal Fluid

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)

Hydrocephalus

Increase in cereberospinal fluid (CSF) volume usually resulting from impaired absorption, rarely from excessive secretion.

This definition excludes ventricular expansion secondary to brain shrinkage from a diffuse atrophic process (Hydrocephalus ex vacuo)

Classification

By Pathophysiology

By Etiology

Obstructive Hydrocephalus

Communicating Hydrocephalus

Congenital Hydrocephalus

Acquired Hydrocephalus

Causes

Non-communicating hydrocephalus

There is no communication between the ventricular system and the subarachnoid space.

The commonest 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 deformitiesPrognosis: 11-30% mortality

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.

Etiology of aqueductal stenosis

Intrinsic Pathology of the Aqueduct

Septum or Membrane Formation: A thin membrane of neuroglia may occlude the aqueduct

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.

Stenosis of the Aqueduct: Narrowed aqueduct without evidence of gliosis. This may have hereditary basis.

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.

T2-weighted MRI of tectal tumor: The tumor (tectal glioma or hamartoma)

Aqueductal stenosis

Dandy Walker SyndromeA common cause of

obstructive hydrocephalus is Dandy Walker Syndrome where there is blockage of foramina of the 4th ventricle (atresia of foramina of Luschka and Magendie)

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.

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 with either unilateral or bilateral occlusion of the foramen of Monroe. Dilatation of one or both lateral ventricles. This is commonly seen in the colloid cyst and tumors of the third ventricle.

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 and there may be an actual shrinkage of brain.

Normal pressure hydrocephalus

Normal pressure hydrocephalus is usually due to a gradual blockage of the CSF drainage pathways. NPH is an unusual cause of dementia, which can occur as a complication of brain infection or bleeding (hemorrhage).

Pathology of Hydrocephalus

Clinical Manifestation

In infants & young children

In adult

InvestigationsX-ray

!!: - skull size, suture width- evidence of chronic raised pressure erosion of the

posterior clinoids)- associated defects

Aqueduct stenosis

3rd ventricle and anterior horns are dilated, 4th ventricle are normal

Normal• CT Scan

Posterior fossa mass

Dilated 3rd and lateral ventricle, deviated or absent 4th ventricle

Communicating hydrocephalus

Dilated lateral, 3rd, normal 4th ventricle

UltrasonographyLess good than CT Scan

Magnetic Resonance ImagingMore clear vision of periventricular lucency, neoplastic mass

Enlargement of the lateral, third, and fourth ventricles and effacement of the subarachnoid space (Panels A and B). No gross transependymal absorption of cerebrospinal fluid was noted. Several small, nonenhancing periventricular areas of hyperintensity were present. Communicating hydrocephalus, presumptively long-standing, was diagnosed.

Intracranial pressure (ICP) monitoringUseful for normal pressure hydrocephalusTo predict the likelihood of a beneficial response to shunting

Developmental assessment & psychometric analysisTo detect impaired cerebral function and provide a baseline for

future comparison

Management

Complications of ShuntingInfections

Subdural haematoma

Shunt obstruction

Low pressure state