Brain abscess Flashcards
What is the epidemiology of brain abscesses?
Rare - 0-1/100,000/yr
What is the aetiology and pathophysiology of brain abscesses?
Local: Ear infection; Dental abscess; Paranasal sinus infection; Epidural abscess; Mastoid air cell (temporal bone) infection; Head trauma or surgical procedure
Remote: Lung; Heart; Kidney infections etc
Abscess = collection of pus built up within body tissue - symptoms occur from a combination of the infection and the space which the abscess is occupying
Bacterial: Anaerobic and microaerophillic cocci and gram negative and gram positive anaerobic bacilli are most common – but all depends on the origin of the infection
Mostly polymicrobial
ii) S.aureus
iii) Strep intermedius
iv) Bacteroides
v) Enterobacteriaceae etc
Fungi in the immunocompromised
How do brain abscesses present?
Fever + Headache +
Focal neurological signs (= classic triad – but uncommon) – depends on location of abscess
Other signs of raised ICP + infection – drowsiness, confusion, seizure
How do you investigate a brain abscess?
Bloods + swabs + urine samples – infection location screen
Contrast CT head/MRI:
Within 4-5 days of abscess formation – inflammation and dead brain tissue form a capsule-like appearance and the ‘ring enhancing lesion’ on contrast CT (as contrast cannot penetrate capsule – looks light around a dark lesion)
LP – contraindicated if raised ICP
How do you manage a brain abscess?
MC+S though blood culture
IV Abx - broad then focus
Managing raised ICP:
Hyperbaric oxygen therapy - Reduces ICP; High PaO2 = bacteriocidal to anaerobes; Optimises immune function; Increase stem cell production + VEGF – better healing/recovery process
Surgical drainage of abscess +/- removal of foreign bodies that may have caused infection
What is the prognosis for brain abscesses?
Depends on the location and size
May have permanent neurodisability or be relatively okay
