Definition: enlargement of the cerebral ventricular system.

Subdivisable into obstructive and non-obstructive, or communicating and non-communicating.

Image result for ventricular system

Aetiology/ risk factors:

-Abnormal accumulation of CSF in the ventricles, leading to raised intracranial pressure, caused by:

Impaired outflow of CSF from the ventricular system (obstructive/ non-communicating):

-lesions of the third ventricle, fourth ventricle, cerebral aqueduct (inc. TB, neurocysticercosis)

-posterior fossa lesions (tumour, blood) compressing fourth ventricle

-cerebral aqueduct stenosis

Impaired CSF resorption in the subarachnoid villi (non-obstructive/communicating):



-subarachnoid haemorrhage

Normal Pressure Hydrocephalus (NPH) = idiopathic chronic ventricular enlargement, long white matter tracts (corona radiate, anterior commissure) are damaged causing gait and cognitive decline


Bimodal age distribution.

Congenital malformations and tumours in the young, and tumours and strokes in the elderly.


-Acute drop in conscious level

-Diplopia (double vision)


-Headache (worse on waking, lying down, bending forward, or coughing)



-Subtle personality change e.g. irritability

NPH = Chronic cognitive decline, falls, urinary incontinence

= wet, wacky, wobbly triad


-impaired GCS (conscious level measure)- drowsiness, listlessness, irritability, coma

-papilloedema, decreased visual acuity, peripheral field loss

-VI nerve palsy (abducens nerve which abducts the eye, this is a ‘false localising’ feature of raised ICP)

-pupil changes (constriction first and later dilation = due to raised ICP)


-head circumference may enlarge (because babies are super stretchy)

-sunset sign = downward conjugate (both) deviation of eyes

Image result for sunset sign hydrocephalus

NPH = cognitive impairment, gait apraxia (shuffling), hyperreflexia


CT- First line investigation to detect hydrocephalus. May also detect cause e.g. tumour.

Image result for ct hydrocephalus

Lumbar puncture- contraindicated in obstructive hydrocephalus as it can cause tonsillar herniation and death.

May be necessary in normal pressure hydrocephalus as a therapeutic trial.

CSF- from puncture, or from ventricular drains- may indicate underlying pathology e.g. TB



-ABC (airway, breathing, circulation)

-protect and secure airway if impaired consciousness

-treat seizures

external ventricular drain = catheter into lateral ventricle to bypass obstruction

ventriculoperitoneal shunting = ventricular catheter into one/both lateral ventricles connected to subcutaneous drain connected to peritoneal cavity

Image result for ventriculoperitoneal shunting

lumboperitoneal shunting = alternative shunt, may be suitable for communicating/ non-obstructive hydrocephalus

Image result for lumboperitoneal shunting

advanced neurosurgery: endoscopic ventriculostomy and aqueductoplasty

-surgical excision of tumours causing obstruction


-cerebral herniation ⇒ coning ⇒ death

-shunt infection, block or malfunction


-Obstructive hydrocephalus often fatal if untreated.

-Cognitive and gait decline in NPH can improve with shunting.

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