1. Brain Abscess

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

3. Pathogenesis? Direct  20-60% of the cases  Focal abscess Hematogenous  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. 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  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/mm 3 with predominately lymphocytes WBC > 1,000/mm 3 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  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