Hydrocephalus

Question 1

Definition

Answer 1

• Enlargement of the cerebral ventricular system.

• It can be subdivided into obstructive and non-obstructive
o AKA communicating and non-communicating

• Hydrocephalus ex vacuo = apparent enlargement of the ventricles as a compensatory change due to brain atrophy

Question 2

Aetiology

Answer 2

Abnormal accumulation of CSF in the ventricles can be caused by:

o OBSTRUCTIVE: Impaired outflow of the CSF from the ventricular system
• Lesions of the 3rd and 4th ventricle or cerebral aqueduct
• Posterior fossa lesions (e.g. tumour) compressing the 4th ventricle
• Cerebral aqueduct stenosis

o NON-OBSTRUCTIVE: Impaired CSF reabsorption into the subarachnoid villi
• Tumours
• Meningitis
• Normal Pressure Hydrocephalus - idiopathic chronic ventricular
enlargement. The long white matter tracts are damaged leading to gait and cognitive decline `

Question 3

Epidemiology

Answer 3

• Bimodal age distribution

o YOUNG - congenital malformations and brain tumours
o ELDERLY - strokes and tumours

Question 4

Presenting symptoms

Answer 4

• Obstructive Hydrocephalus
o Acute drop in conscious level
o Diplopia

• Normal Pressure Hydrocephalus
o Triad of symptoms:
• Dementia
• Gait disturbance
• Urinary incontinence

Question 5

Signs on physical examination (obstructive hydrocephalus)

Answer 5

• Obstructive Hydrocephalus

o Low GCS

o Papilloedema

o 6th nerve palsy
• 6th nerve has the longest intracranial path of all the cranial nerves and so is
most susceptible to palsy due to raised ICP

o NEONATES:
• Increased head circumference
• Sunset sign (downward conjugate deviation of the eyes)

Question 6

Signs on physical examination (normal pressure hydrocephalus)

Answer 6

o Cognitive impairment
o Gait apraxia (shuffling)
o Hyperreflexia

Question 7

Investigations

Answer 7

• CT Head
o FIRST-LINE for detecting hydrocephalus
o May also pick up the cause (e.g. tumour)

• CSF
o From ventricular drain or lumbar puncture
o May indicate pathology (e.g. tuberculosis)
o Check MC&S, protein and glucose

• Lumbar Puncture
o IMPORTANT: contraindicated if raised ICP
o Therapeutic in normal pressure hydrocephalus