Download Brain Abscess

Brain Abscess
What is brain abscess?
Focal collection within brain
parenchyma
Pathogenesis?
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Direct
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20-60% of the cases
Focal abscess
Hematogenous
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Multiple abscesses
No identifiable souces in 20-40% of the cases
Primary sources in direct spread and
distribution of abscess
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Otitis media – inferior temporal lobe and
cerebellum
Frontal or ethmoid sinuses – frontal lobe
Dental caries – frontal lobe
Foreign bodies - bullet
Primary sources hematogenous spread
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Chronic pulmonary infections – lung abscess
and empyema
Skin infection
Intrabdominal and pelvic infection
Bacterial endocarditis
Cyanotic congenital heart disease – most
common in children
Microbiology
Clues to the primary source
Anaerobics
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Usually mouth flora
May be from pelvic or intraabdominal
infections – multiple abscesses
Examples – anaerobic streptococci,
bacteroides species, fusobacterium
Aerobics
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Gram positive
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Staphylococcus aureus – neurosurgery and trauma
Streptococcus milleri – proteolytic enzymes that cause
necrosis
Others – viriddans streptococci, microaerophilic streptocci
Gram negative
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Usually from trauma or neurosurgery
Klebsiella pneumoniae, Pseudodomonas species, E. coli,
and Proteus species
Immunocompromised hosts?
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Opportunistic infections
Toxoplasma gondii
Listeria
Fungi – Aspergillus, cryptococcus
neoformans, coccidiodidides immitis,
Candida albicans
Immigrants
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Parasites
Cysticercosis – 85% of brain infection in
Mexico city
Symptoms?
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Headache – most common
Neck stiffness
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Associated with occipital abscess
Abscess leaks into lateral ventricle
Altered mental status – cerebral edema
Vomiting – increased intracranial pressure
Physical finding?
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Fever – not very reliable, since only 45-50% present
Focal neurological deficit – days or weeks after
onset of headache
Seizure
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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
Tests?
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CT scan with contrast
MRI with gadolinium diethylenetriamine
Lumbar puncture
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Contraindicated
Analysis
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WBC < 500/mm3 with predominately lymphocytes
WBC > 1,000/mm3 consistent with meningitis but not
improved with antibiotics, consider MRI for ruptured
abscess
Treatment options?
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Antibiotics – 6 to 8 weeks
Surgical drainage
Antibiotics?
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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
Indications for surgical drainage?
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No clinical improvement within a week
Depressed sensorium
Increased intracranial pressure
Progressive increase in the ring diameter of
the abscess
Surgical approach
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Needle aspiration
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Prefer approach because of less neurological
deficit
Under ultrasound or CT guided
Surgical excision
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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
Steroid use?
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Mainly for mass effect
Disadvantages
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Reduce contrast enhancement on CT scan
Slow capsule formation
Increase risk of rupture
Decrease penetration of antibiotics
Complications
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Neurological deficits – commonly seizure with
frontal lesion
Poor prognosis – mortality rate up to 30%
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Rapid progression of the infection
Severe mental changes
Rupture into ventricle