Neurological disease in a child: Hydrocephalus

Question 1

Define hydrocephalus.

Answer 1

Excess CSF from abnormal flow, absorption or production.

Question 2

What is obstructive hydrocephalus?

Answer 2

Disruption in the flow of CSF within the ventricular system

• Aqueductal stenosis or atresia: Most common site of intraventricular obstruction in infants with congenital hydrocephalus.
• Obstruction of the 4th ventricle: DandyWalker syndrome (cystic dilatation of the 4th ventricle with cerebellar hypoplasia).
• Obstruction due to intracranial mass lesion: Tumours of the posterior fossa (medulloblastoma, astrycytoma, ependymoma), haematomas, vein of Galen aneurysm.

Question 3

What is communicating hydrocephalus?

Answer 3

Disruption in the flow of CSF in the surface pathways

• Arnold-Chiari malformations: Herniation of cerebellar tonsils through the foramen magnum, frequently associated with neural tube defects:
  
  • Myelomeningocoele: Outpouching of the spinal cord through the posterior bony vertebral coloumn
  • Cranial meningocoele: Meningeal sac protrudes through a skull defect
• Encephalocoele: Protrusion of cerebral tissue through midline cranial defect located in frontal or occipital regions.
• Meningeal adhesions: Secondary to inflammation (meningitis) or haemorrhage (intraventricular or subarachnoid)

Question 4

What does increased production of CSF cause?

Answer 4

Choroid plexus papilloma: Rare cause of hydrocephalus

Question 5

What are risk factors for hydrocephalus?

Answer 5

Family history, neurofibromatosis (NF).

Question 6

Explain the aetiology of hydrocephalus.

Answer 6

Accumulation of CSF in a confined space leads to increased intraventricular pressure and raised ICP. In infants there is initial compensation from open fontanelles.

Question 7

Summarise the epidemiology of hydrocephalus.

Answer 7

Congenital hydrocephalus: 3-5/1000 live births

Question 8

What are symptoms of hydrocephalus in infants?

Answer 8

Slow progression: Infants may thrive and develop normally apart from poor head control

Rapid progression: Irritability, lethargy, failure to gain weight and achieve developmental milestones, vomiting

Question 9

What are symptoms of hydrocephalus in older children?

Answer 9

Posterior fossa tumours: Cerebellar signs: ataxic gait, dyspraxia, slurred speech

‘Arrested’ hydrocephalus: Rare condition in which there is stable ventriculomegaly in the presence of a child with stable neurology

Question 10

What are signs of hydrocephalus?

Answer 10

• Progressive increase in occipitofrontal head circumference or >97th centile.
• Wide open bulging anterior fontanelle.
• Widening of the coronal, sagittal and lamboidal sutures.
• Eyes deviate downwards (‘setting sun’ sign).
• Papilloedema (uncommon in congenital hydrocephalus).

Question 11

What are appropriate investigations for hydrocephalus?

Answer 11

CT/USS: May show dilation of ventricles and any tumours or cysts present.

MRI: Shows greater anatomical detail, and with contrast illustrates flow through the aqueduct.

Question 12

What is the management for hydrocephalus?

Answer 12

Surgical: Insertion of a shunt with a one-way valve from the ventricle to the peritoneum (or the right atrium).

Supportive: Requires long-term MDT follow-up to provide support for neurological sequelae.

Question 13

What are complications associated with hydrocephalus?

Answer 13

Shunt complications: Obstruction, infection, especially Staphylococcus epidermidis. Overdrainage can lead to subdural haemorrhage.

Long-term sequelae: Global developmental delay, impaired memory and vision, precocious puberty.

Question 14

What is the prognosis of hydrocephalus?

Answer 14

Some forms of hydrocephalus are temporary, such as meningeal adhesion secondary to infection or haemorrhage; some forms give rise to limited ventricular enlargement and then cease: compensated hydrocephalus.

However, in most cases the ventricles will continue to enlarge and compress brain matter, resulting in a very poor prognosis.