Hydrocephalus Ex Vacuo

What the term means

Cerebrospinal fluid (CSF) fills the ventricles inside the brain and the spaces around it. In true hydrocephalus, CSF builds up because its flow or absorption is blocked, raising pressure and pushing the ventricles outward. In hydrocephalus ex vacuo, the brain tissue itself has shrunk, so the ventricles and the grooves on the brain's surface (sulci) widen passively to fill the space. Pressure stays normal.

Many radiologists now avoid the term because it is not true hydrocephalus. You may see "ex vacuo dilatation," "ventriculomegaly with proportionate sulcal enlargement" or "volume loss" on reports instead.

Causes

• normal aging: some brain volume loss is expected after about age 60
• Alzheimer's disease and other neurodegenerative diseases such as frontotemporal dementia and Huntington's disease
• stroke: loss of tissue in one area can enlarge the nearby ventricle (focal ex vacuo change)
• traumatic brain injury
• long-term heavy alcohol use
• HIV infection and other chronic brain infections
• multiple sclerosis
• schizophrenia, where modest ventricular enlargement has been described

Symptoms

Hydrocephalus ex vacuo does not cause symptoms by itself. Any symptoms reflect the condition that caused the brain tissue loss, for example:

• memory loss and thinking problems in dementia
• weakness, speech or vision problems after a stroke
• personality and behavior changes
• balance problems

How it differs from normal pressure hydrocephalus

The most important clinical task is telling ex vacuo change apart from normal pressure hydrocephalus (NPH), because NPH can improve with a shunt.

Both can coexist, especially in older adults, which can make diagnosis challenging.

Diagnosis

• MRI or CT scan: shows the pattern of ventricular and sulcal enlargement, areas of stroke and regional atrophy that suggests specific dementias. The Evans index measures ventricle size relative to the skull.
• Clinical assessment: cognitive testing, walking assessment and history.
• Lumbar puncture tap test or extended lumbar drain: when NPH is possible, removing CSF and watching for improvement in walking.
• Other tests: blood tests for reversible causes of cognitive impairment, such as vitamin B12 and thyroid levels.

Treatment

Because the ventricles enlarge passively, there is nothing to drain. Shunt surgery does not help and carries risks.

Management focuses on the cause:

• dementia care: medicines such as cholinesterase inhibitors where appropriate, support for daily living, safety planning
• stroke prevention: blood pressure control, antiplatelet drugs or anticoagulants, statins
• stopping alcohol and treating nutritional deficiencies
• rehabilitation after brain injury or stroke: physical, occupational and speech therapy
• regular physical activity, social engagement and control of vascular risk factors, which support brain health

Outlook

The outlook depends entirely on the underlying cause. Ex vacuo change from aging alone is a common finding and may have little effect on daily life. When caused by progressive conditions such as Alzheimer's disease, the course follows that condition.

Frequently asked questions

What does hydrocephalus ex vacuo mean?

It means the fluid spaces of the brain look larger because brain tissue has shrunk, not because fluid is building up. The fluid fills the space left behind. It reflects brain atrophy from aging, dementia, stroke or injury.

Is hydrocephalus ex vacuo serious?

The enlargement itself is not dangerous and does not raise pressure in the head. Its significance depends on the cause. Mild changes with age are common. Changes caused by dementia, stroke or brain injury reflect those conditions.

Can hydrocephalus ex vacuo be treated with a shunt?

No. A shunt drains excess fluid under pressure, but in hydrocephalus ex vacuo the fluid is simply filling space left by lost tissue. Treatment focuses on the condition that caused the brain tissue loss.

What is the difference between hydrocephalus ex vacuo and normal pressure hydrocephalus?

In ex vacuo change, brain tissue loss causes ventricle enlargement. In normal pressure hydrocephalus, fluid absorption is impaired, causing walking difficulty, bladder problems and memory issues that may improve with a shunt. MRI patterns and a lumbar tap test help tell them apart.

Is enlarged ventricles on an MRI normal with age?

Some enlargement of the ventricles and widening of the brain's surface grooves is common with aging. Your doctor will interpret it alongside your age, symptoms and other scan findings to decide whether further evaluation is needed.