excessive level of CSF in thje ventricular system, caused by an imbalance between CSF production and absorption

Pathophysiology

Obstructive hydrocephalus: due to a structural pathology blocking the flow of cerebrospinal fluid. Dilatation of the ventricular system is seen superior to site of obstruction. Causes include:

• tumours
• acute haemorrhage (e.g. subarachnoid haemorrhage or intraventricular haemorrhage)
• developmental abnormalities (e.g. aqueduct stenosis).

Non-obstructive hydrocephalus: due to an imbalance of CSF production absorption. It is either caused by an increased production of CSF (e.g. choroid plexus tumour (very rare) or more commonly a failure of reabsorption at the arachnoid granulations (e.g. meningitis or post-haemorrhagic).

• NPH is a unique form of non-obstructive hydrocephalus

PC

Sx due to raised ICP:

• Headache (typically worse in the morning, when lying down and during valsalva)
• Nausea and vomiting
• Papilloedema
• Coma (in severe cases)

Paediatrics:

• Bulging anterior fontanelle (skull sutures not yet fused) = increase in head circumference