NG-317

🦠 Brain Abscess

A walled-off pocket of infection inside the skull. An infection and a space-occupying lesion at the same time.

🧬 What it is

A head in cross-section with the middle ear and sinuses marked and arrows running the short distance from each into the brain, where a ring-enhancing abscess sits, plus the lumbar puncture that must not be done. — An untreated ear or sinus infection sits millimeters from the brain. That is the exam pathway, and it is anatomical. Swipe it sideways if it is cut off, or tap to open it full size.

Two problems in one. It is an infection, so it causes fever and raised white cells. It is also a mass inside a box that cannot expand, so it raises intracranial pressure.

Treat it as both: antibiotics AND the full ICP protocol.

Route in	Typical source
Direct spread	Otitis media, mastoiditis, sinusitis, dental infection
Bloodborne	Endocarditis, lung abscess, IV drug use
Penetrating	Skull fracture, neurosurgery, trauma

This is why an untreated ear or sinus infection matters. Chronic otitis media and mastoiditis sit millimeters from the brain, and that is the classic exam pathway.

👀 How it shows up

The triad:

1Headache — usually the first and worst symptom

2Fever — though it may be low grade or absent

3Focal deficit — depends where the abscess sits

Plus rising ICP: nausea and projectile vomiting, change in LOC, seizures, papilledema.

Fever is unreliable here - up to half of patients do not have one. A worsening headache with a new neurological deficit is enough to investigate.

🧪 Diagnosis

MRI with contrast — the test of choice; shows a ring-enhancing lesion
CT with contrast if MRI unavailable
Blood cultures before antibiotics
Aspiration for culture guides definitive antibiotic choice

Lumbar puncture is contraindicated when a mass and raised ICP are suspected - removing CSF from below can cause herniation.

🩺 Treatment and nursing care

High-dose IV antibiotics that cross the blood–brain barrier, often for 6–8 weeks
Surgical aspiration or excision for larger abscesses
Anticonvulsants — seizures are common and spike ICP
Dexamethasone if edema is significant

🚨 Nursing priorities

Neuro observations — LOC is the earliest marker of deterioration
ICP precautions — HOB 30°, head midline, no neck or hip flexion, avoid Valsalva
Seizure precautions from admission
Antibiotics strictly on schedule — levels must stay above the killing concentration
Monitor for long-line complications over a many-week course
Temperature control — fever raises cerebral metabolic demand

🎯 NCLEX traps

It is both an infection and a mass — expect ICP precautions, not just antibiotics
No lumbar puncture with a suspected mass
Cultures before antibiotics
Treating ear, sinus and dental infections properly is the prevention

Sources. Written from MedlinePlus, National Cancer Institute, NINDS and OpenStax A&P 2e (CC BY 4.0).