Hydrocephalus

Question 1

Define hydrocephalus

Answer 1

DEFINITION: enlargement of the cerebral ventricular system.

Question 2

What are the 3 subdivisions of hydrocephalus?

Answer 2

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

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

Question 3

Explain the aetiology/risk factors of hydrocephalus

Answer 3

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

○ 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

○ 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 4

Summarise the epidemiology of hydrocephalus

Answer 4

• Bimodal age distribution
○ YOUNG - congenital malformations and brain tumours
○ ELDERLY - strokes and tumours

Question 5

Recognise the presenting symptoms of hydrocephalus

Answer 5

• Obstructive Hydrocephalus
○ Acute drop in conscious level
○ Diplopia

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

Question 6

What are the signs of hydrocephalus on physical examination

Answer 6

• Obstructive Hydrocephalus
○ Low GCS
○ Papilloedema
○ 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

○ NEONATES:
• Increased head circumference
• Sunset sign (downward conjugate deviation of the eyes)
• Normal Pressure Hydrocephalus
○ Cognitive impairment
○ Gait apraxia (shuffling)
○ Hyperreflexia

Question 7

Identify appropriate investigations for hydrocephalus

Answer 7

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

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

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