1. Brain Abscess

2. Focal collection within brain parenchyma
What is brain abscess?
Focal collection within brain parenchyma

3. Pathogenesis? Direct Hematogenous 20-60% of the cases Focal abscess
Multiple abscesses
No identifiable souces in 20-40% of the cases

4. Primary sources in direct spread and distribution of abscess
Otitis media – inferior temporal lobe and cerebellum
Frontal or ethmoid sinuses – frontal lobe
Dental caries – frontal lobe
Foreign bodies - bullet

5. Primary sources hematogenous spread
Chronic pulmonary infections – lung abscess and empyema
Skin infection
Intrabdominal and pelvic infection
Bacterial endocarditis
Cyanotic congenital heart disease – most common in children

6. Clues to the primary source
Microbiology
Clues to the primary source

7. Anaerobics Usually mouth flora
May be from pelvic or intraabdominal infections – multiple abscesses
Examples – anaerobic streptococci, bacteroides species, fusobacterium

8. Aerobics Gram positive Gram negative
Staphylococcus aureus – neurosurgery and trauma
Streptococcus milleri – proteolytic enzymes that cause necrosis
Others – viriddans streptococci, microaerophilic streptocci
Gram negative
Usually from trauma or neurosurgery
Klebsiella pneumoniae, Pseudodomonas species, E. coli, and Proteus species

9. Immunocompromised hosts?
Opportunistic infections
Toxoplasma gondii
Listeria
Fungi – Aspergillus, cryptococcus neoformans, coccidiodidides immitis, Candida albicans

10. Immigrants
Parasites
Cysticercosis – 85% of brain infection in Mexico city

11. Symptoms? Headache – most common Neck stiffness
Associated with occipital abscess
Abscess leaks into lateral ventricle
Altered mental status – cerebral edema
Vomiting – increased intracranial pressure

12. Physical finding? Fever – not very reliable, since only 45-50% present
Focal neurological deficit – days or weeks after onset of headache
Seizure
25% of the cases
May be first manifestation of brain abscess
Grand mal in frontal infection
Third or sixth cranial palsy – increased intracranial pressure
Papilledema – cerebral edema

13. Tests? CT scan with contrast MRI with gadolinium diethylenetriamine
Lumbar puncture
Contraindicated
Analysis
WBC < 500/mm3 with predominately lymphocytes
WBC > 1,000/mm3 consistent with meningitis but not improved with antibiotics, consider MRI for ruptured abscess

14. Treatment options?
Antibiotics – 6 to 8 weeks
Surgical drainage

15. Antibiotics?
Penicillin G – aerobic and anaerobic streptococci from mouth flora
Metronidazole – against anaerobes but not aerobes, good intralesional penetration
Ceftriaxone or cefotaxime – Enterobacteraciae, particular chronic ear infection
Ceftazidime – neurosurgery and p. aeruginosa
Oxacillin or nafcillin – head trauma or neurosurgery, mainly staphylococcus aureus coverage
Vancomycin – MRSA
Aminoglycosides – poor blood brain barrier, not use

16. Indications for surgical drainage?
No clinical improvement within a week
Depressed sensorium
Increased intracranial pressure
Progressive increase in the ring diameter of the abscess

17. Surgical approach Needle aspiration Surgical excision
Prefer approach because of less neurological deficit
Under ultrasound or CT guided
Surgical excision
More neurological deficit
Prefer in traumatic abscess, particularly with foreign body,and encapsulated fungal abscess
Advantages: shorten antibiotics to 2 to 4 weeks and less relapse

18. Steroid use? Mainly for mass effect Disadvantages
Reduce contrast enhancement on CT scan
Slow capsule formation
Increase risk of rupture
Decrease penetration of antibiotics

19. Complications
Neurological deficits – commonly seizure with frontal lesion
Poor prognosis – mortality rate up to 30%
Rapid progression of the infection
Severe mental changes
Rupture into ventricle