Brain abscess

A pocket of pus in the brain. Headache with fever and any new neurological sign needs a scan, not a painkiller.

What it is

A collection of pus within the brain, from infection spreading from the ear, sinuses or teeth, from the bloodstream, or after head injury or surgery.

It is rare and it is fatal if untreated. The mass grows, pressure inside the skull rises, and the person deteriorates over days to weeks.

The classic triad is headache, fever and a focal neurological sign, but fewer than half of people have all three, which is why it is missed. **A new, persistent, severe headache with fever, or with any new neurological symptom, deserves imaging.**

The commonest sources are worth knowing because they are treatable earlier: chronic middle ear infection and cholesteatoma, sinusitis, dental abscess, and endocarditis. It also occurs in people with congenital heart disease with right-to-left shunts, and in the immunosuppressed.

Treatment is drainage or removal plus prolonged antibiotics, often six to eight weeks.

Around half of survivors have lasting effects, most commonly epilepsy, which frequently develops months later, and cognitive or personality changes.

Signs you might notice

Headache, usually persistent, severe, and different from any usual headache, often worse in the morning.

Fever, though a third of people have none.

Nausea and vomiting.

Drowsiness, confusion, or personality change.

Weakness, numbness, visual disturbance, or difficulty speaking.

Seizure.

A stiff neck.

**999 or A and E** for headache with fever, drowsiness, confusion, seizure or any new neurological sign.

Take it especially seriously in anybody with a long-standing discharging ear, chronic sinusitis, a dental abscess, congenital heart disease, or a weakened immune system.

Do not treat a new severe headache with fever as a migraine.

How it can affect day-to-day life

The chronic discharging ear is the classic missed source. An ear that has run for years is not normal and can erode into the skull; see cholesteatoma.

Dental abscesses are frequently left because dental access is difficult and expensive, and untreated dental infection is a genuine route to this.

Recovery involves weeks of intravenous antibiotics, often at home, and prolonged rehabilitation.

Epilepsy is common afterwards and may start months later, so people need to know the signs and the driving rules.

Cognitive and personality change is common, under-recognised, and needs neuropsychology assessment rather than being attributed to low mood.

Families frequently describe a long period of being told it was stress or a virus before anybody scanned.

Supporting someone well

Treat a new severe persistent headache with fever, drowsiness or any neurological change as an emergency.

Say the source out loud: a discharging ear, chronic sinusitis, a bad tooth, congenital heart disease.

Get chronic ear discharge assessed by ENT rather than treated with repeated drops.

Get dental infection treated; it is not a cosmetic issue.

Ask for imaging rather than accepting a diagnosis of migraine or viral illness with these features.

Afterwards, ask about seizure risk, what to do in a seizure, and driving rules.

Ask for neuropsychology assessment for memory, concentration and personality changes.

Complete the full antibiotic course, which will be long.

Where to get help

999 or A and E immediately.

Neurosurgery, and ENT or dental services for the source.

Brain and Spine Foundation run a helpline and cover recovery.

Headway on 0808 800 2244 for the cognitive aftermath.