Neurological disorder characterized by an excessive accumulation of CSF within the brain's ventricular system, leading to ventricular enlargement or ventriculomegaly

Aetiology

• Obstructive (or non-communicating) hydrocephalus: occurs when the flow of CSF is blocked along one or more of the narrow passages connecting the ventricles
  • Common sites of obstruction include the foramen of Monro (e.g. due to colloid cysts), cerebral aqueduct (e.g. due to aqueduct stenosis), or fourth ventricle (e.g. due to posterior fossa tumour)
• Communicating hydrocephalus: in this type, CSF can exit the ventricular system, but absorption into the bloodstream is impeded
  • This is commonly due to problems in the subarachnoid space, often stemming from complications like subarachnoid haemorrhage and infective meningitis

Clinical features

Often present with symptoms related to increased intracranial pressure, including:

• Early morning headaches
• Nausea and vomiting
• Lethargy
• Vision disturbances
• Balance problems
• Cognitive difficulties

Investigations

• CT: can reveal ventricular enlargement, is generally the initial imaging modality
• MRI: provides a more detailed view of the brain and can help to determine the cause of the hydrocephalus

Management

• Surgical insertion of a shunt to allow the excess CSF to drain from the brain to another part of the body e.g. heart or peritoneal cavity where it can be more easily absorbed
  • Regular follow-up required
• In some cases, endoscopic third ventriculostomy (ETV) may be performed. This involves creating a hole in the bottom of one of the ventricles or between ventricles to allow the CSF to flow out of the brain