Brain Abscess

Definition

A brain abscess is a collection of pus, immune cells, and other material in the brain, usually caused by a bacterial or fungal infection. It is a serious and potentially life-threatening condition that requires prompt medical treatment.

Aetiology

Brain abscesses can be caused by:

Bacterial infections: Streptococci, Staphylococci, anaerobes
Fungal infections: Aspergillus, Candida
Parasitic infections: Toxoplasma gondii (rare)
Direct extension from nearby infections: Sinusitis, otitis media, dental infections
Haematogenous spread from distant infections: Endocarditis, lung abscess
Trauma or neurosurgical procedures

Pathophysiology

The infection leads to a localised collection of pus in the brain parenchyma, causing inflammation, tissue necrosis, and oedema. This results in increased intracranial pressure and potential damage to brain tissue.

Risk Factors

Immunocompromised state (e.g., HIV/AIDS, immunosuppressive therapy)
Chronic sinusitis or otitis media
Dental infections
Congenital heart disease
Recent head trauma or neurosurgery

Signs and Symptoms

Headache
Fever
Neurological deficits (e.g., focal weakness, aphasia)
Seizures
Altered mental status
Nausea and vomiting

Investigations

Clinical history and physical examination
Neuroimaging: MRI (preferred) or CT scan with contrast
Blood tests: Full blood count, inflammatory markers (CRP, ESR), blood cultures
Aspiration and culture of abscess material (if safe and feasible)

Management

Primary Care Management

Immediate referral to hospital for suspected brain abscess
Initial supportive care (e.g., pain management, fever control)

Specialist Management

Empirical antibiotic therapy: Broad-spectrum antibiotics (e.g., ceftriaxone, metronidazole) adjusted based on culture results
Antifungal therapy if a fungal infection is suspected or confirmed
Neurosurgical intervention: Aspiration or excision of the abscess if indicated
Management of complications: Anticonvulsants for seizures, steroids to reduce cerebral oedema
Supportive care: Intravenous fluids, monitoring in an intensive care unit if necessary

Example Management for Brain Abscess

A patient presenting with a suspected brain abscess should be referred to hospital immediately. Initial empirical antibiotic therapy might include intravenous ceftriaxone and metronidazole. Surgical aspiration of the abscess may be performed for diagnostic and therapeutic purposes. The patient should be monitored closely in an intensive care setting if severe symptoms or complications are present.

References

NICE. (2024). Brain Abscess: Diagnosis and Management. Retrieved from NICE
NHS. (2023). Brain Abscess. Retrieved from NHS
Brook, I. (2017). Microbiology and Management of Brain Abscesses. Clinical Microbiology Reviews.
Connolly, E. S., & Rabinstein, A. A. (2020). Current Therapy in Neurological Surgery. Elsevier.
Solomon, T., Michael, B. D., Smith, P. E., & Sanderson, F. (2022). Infections of the Central Nervous System. Oxford University Press.