Normal pressure hydrocephalus is a reversible cause of dementia seen in elderly patients. It is thought to be secondary to reduced CSF absorption at the arachnoid villi. These changes may be secondary to head injury, subarachnoid haemorrhage or meningitis.

Diagnosis

A classical triad of features is seen

1. urinary incontinence
2. dementia and bradyphrenia
3. gait abnormality (may be similar to Parkinson's disease)

It is thought around 60% of patients will have all 3 features at the time of diagnosis. Symptoms typically develop over a few months.

Imaging

• hydrocephalus with ventriculomegaly in the absence of, or out of proportion to, sulcal enlargement

CT scan of an elderly male patient showing hydrocephalus, with dilatation of the third ventricle and lateral ventricles with the characteristic absence of sulcal enlargement - e Image used on license from Radiopaedia

Management

• ventriculoperitoneal shunting
• around 10% of patients who have shunts experience significant complications such as seizures, infection and intracerebral haemorrhages