CNS abscess - CNS ABSCESSES CNS ABSCESSES Nov 10, 2003...

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Unformatted text preview: CNS ABSCESSES CNS ABSCESSES Nov 10, 2003 Gebre K Tseggay, MD CNS ABSCESSES CNS ABSCESSES • Focal pyogenic infections of the central nervous system • Exert their effects mainly by: – Direct involvement & destruction of the brain or spinal cord – Compression of parenchyma – Elevation of intracranial pressure – Interfering with blood &/or CSF flow • Include: Brain abscess, subdural empyema, intracranial epidural abscess, spinal epidural abscess , spinal cord abscess BRAIN ABSCESS BRAIN ABSCESS • Accounts for ~ 1 in 10,000 hospital admissions in US (1500-2500 cases/yr) • Major improvements realized in diagnosis & management the last century, & especially over the past three decades, with: BRAIN ABSCESS BRAIN ABSCESS • Was uniformly fatal before the late 1800’s • Mortality down to 30-60% from WWII-1970’s – Introduction of abx (penicillin, ...) – newer surgical techniques • Mortality down to 0-24% over the past three decades, with: – Advent of CT scanning (1974) , MRI – Stereotactic brain biopsy/aspiration techniques – Further improvement in surgery – Newer abx (e.g. cephalosporins, metronidazole..) – Better treatment of predisposing conditions CHANGES IN EPIDEMIOLOGY CHANGES IN EPIDEMIOLOGY OF BRAIN ABSCESS OF BRAIN ABSCESS (in the last 2-3 decades) (in the last 2-3 decades) – Marked drop in mortality overall – Lower incidence of otogenic brain abscesses – improved treatment of chronic ear infections – With increase in No. of immunosuppressed patients: • increased incidence of brain abscess seen in that population (Transplant, AIDS,…) • More incidence of brain abscess caused by opportunistic pathogens (fungi, toxo…) PATHOPHYSIOLOGY PATHOPHYSIOLOGY • Begins as localized cerebritis (1-2 wks) • Evolves into a collection of pus surrounded by a well-vascularized capsule (3-4 wks) • Lesion evolution ( based on experimental animal models ): – Days 1-3: “early cerebritis stage” – Days 4-9: “late cerebritis stage” – Days 10-14: “early capsule stage” – > day14: “late capsule stage” PATHOGENESIS PATHOGENESIS • Direct spread from contiguous foci (40-50%) • Hematogenous (25-35%) • Penetrating trauma/surgery (10%) • Cryptogenic (15-20%) DIRECT SPREAD DIRECT SPREAD (from contiguous foci) (from contiguous foci) • Occurs by: – Direct extension through infected bone – Spread through emissary veins, diploic veins, local lymphatics • The contiguous foci include : • Otitis media/mastoiditis • Sinusitis • Dental infection (<10%), typically with molar infections • Meningitis rarely complicated by brain abscess (more common in neonates with Citrobacter diversus meningitis, of whom 70% develop brain abscess) HEMATOGENOUS SPREAD HEMATOGENOUS SPREAD (from remote foci) (from remote foci) • Sources: – Empyema, lung abscess, bronchiectasis, endocarditis, wound infections, pelvic infections, intra-abdominal source, etc… – may be facilitated by cyanotic HD, AVM....
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This note was uploaded on 01/06/2012 for the course STEP 1 taught by Professor Dr.aslam during the Fall '11 term at Montgomery College.

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CNS abscess - CNS ABSCESSES CNS ABSCESSES Nov 10, 2003...

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