Hydrocephalus

Question 1

What is the definition of a hydrocephalus?

Answer 1

An enlargement of the cerebral ventricular system

Question 2

What can hydrocephaluses be subdivided into?

Answer 2

• Obstructive / non-communicating

- Non-obstructive / communicating

Question 3

What is a Hydrocephalus ex vacuo?

Answer 3

Apparent enlargement of the ventricles as a compensatory change due to brain atrophy

Question 4

What is the difference between obstructive and non-obstructive hydrocephaluses?

Answer 4

OBSTRUCTIVE: Impaired outflow of the CSF from the ventricular system

NON-OBSTRUCTIVE: Impaired CSF reabsorption into the subarachnoid villi

Question 5

What is the aetiology / risk factors involved with obstructive hydrocephaluses?

Answer 5

Abnormal accumulation of CSF in ventricles due to impaired outflow of CSF from ventricular system due to:

• Lesions of the 3rd and 4th ventricle or cerebral aqueduct
• Posterior fossa lesions (e.g. tumour) compressing the 4th ventricle
• Cerebral aqueduct stenosis

Question 6

What is the aetiology/ risk factors involved with non-obstructive hydrocephaluses?

Answer 6

Abnormal accumulation of CSF in ventricles due to impaired CSF reabsorption into the subarachnoid villi due to:

• Tumours
• Meningitis
• Normal Pressure Hydrocephalus - idiopathic chronic ventricular enlargement. The long white matter tracts are damaged leading to gait and cognitive decline

Question 7

Summarise the epidemiology of hydrocephalus.

Answer 7

There is a bimodal age distribution:

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

Question 8

What are the presenting symptoms of an obstructive hydrocephalus?

Answer 8

Acute drop in conscious level

Diplopia

Question 9

What are the presenting symptoms of a normal pressure hydrocephalus?

Answer 9

Presents with a triad of symptoms involving:

Dementia

Gait disturbance

Urinary incontinence

Question 10

What are the signs of an obstructive hydrocephalus on examination?

Answer 10

IN ADULTS:

• 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

IN NEONATES:

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

Question 11

What are the signs of a normal pressure hydrocephalus on examination?

Answer 11

Cognitive impairment

Gait apraxia (shuffling)

Hyperreflexia

Question 12

What are the appropriate investigations for hydrocephalus?

Answer 12

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