Hydrocephalus

 Hydrocephalus

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):

-tumours

-meningitis

-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

Epidemiology:

Bimodal age distribution.

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

Symptoms:

-Acute drop in conscious level

-Diplopia (double vision)

-Blackout

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

-Vomiting

-Seizures

-Subtle personality change e.g. irritability

NPH = Chronic cognitive decline, falls, urinary incontinence

= wet, wacky, wobbly triad

Signs:

-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)

Neonates

-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

Investigations:

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

Management:

Emergency-

-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

Complications:

-cerebral herniation ⇒ coning ⇒ death

-shunt infection, block or malfunction

Prognosis:

-Obstructive hydrocephalus often fatal if untreated.

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

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