Brain abscess & empyema

Question 1

What is a brain abscess?

Answer 1

Focal bacterial* infection causing an expanding localized area of pus within the brain

Usually polymicrobial containing:

Streptococci in 70% cases

Anaerobes in 40-100% cases

Question 2

What are the causes/risk factors for an abscess to form?

Answer 2

Penetrating head injury

Spread from adjacent infection

• Dental, Sinusitis, Otitis media

Bloodborne infection

• e.g. Bacterial endocarditis

Neurosurgical procedure

Question 3

What is empyema?

Answer 3

Thin layer of pus between the dura and arachnoid membranes over the surface of the brain

Very similar to brain abscess in terms of bacteria n all that shite

Question 4

What are the clinical features of brain abscess?

Answer 4

• Fever, Headache

- Focal symptoms & signs:

• Seizures, dysphasia, hemiparesis etc

- Raised intracranial pressure:

• Papilloedema
• Depressed state of consciousness

± Meningism (more common with empyema though)

• Features of underlying source:
• Dental, ear, sinus infection etc

Question 5

Differential diagnosis for brain abscess

Answer 5

Any focal lesion - most commonly a tumour

Empyema (meningism?)

Subdural haematoma

Question 6

Investigations for Brain abscess

Answer 6

On presentation:

• GCS score - will measure conscious level (raised intracranial pressure)
  
  • Cant make differential diagnosis with this tho

Diagnosis:

• Urgent Imaging: CT or MRI
• Detailed investigation of source - examination of ears, sinuses, teeth
• Blood cultures
• Biopsy (drainage of pus)

Question 7

How is Brain abscess treated?

Answer 7

Neurosurgical aspiration with stereotactic guidance

IV antibiotics:

• Penicillin or Ceftriaxone to cover Streps
• Metronidazole for Anaerobes

Question 8

Prognosis for Brain abscess

Answer 8

25% mortality even with treatment

Epilepsy is fairly common amongst survivors

Question 9

What is empyema?

Answer 9

Thin layer of pus between the dura and arachnoid membranes over the surface of the brain

Similar to brain abscess in terms of pretty much everything

Question 10

What causes empyema?

Answer 10

Penetrating head injury

Spread from adjacent infection - Ears, teeth, sinuses

Bloodborne infection - bacterial endocarditis

Neurosurgical procedure

Question 11

Investigation for empyema?

Answer 11

Same as BA

Imaging - CT / MRI

Investigate underlying source

Blood cultures

Biopsy (drainage)

Question 12

How does Empyema present?

Answer 12

Fever, headache

Meningism

Focal symptoms/signs - seizures, dysphasia etc

Raised intracranial pressure signs - conscious level, papilloedema

Features of underlying source - ears, teeth etc

Question 13

How is empyema treated?

Answer 13

Stereotactic drainage

Penicillin/Ceftriaxone for Streps

Metronidazole for Anaerobes