Brain Abscess 2006 03 14 Definitions Focal pyogenic

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Brain Abscess 神經內科 洪國華 2006 -03 -14

Brain Abscess 神經內科 洪國華 2006 -03 -14

Definitions • • Focal pyogenic infection of the brain parenchyma, typically bacterial; fungal or

Definitions • • Focal pyogenic infection of the brain parenchyma, typically bacterial; fungal or parasitic less common Four pathologic stages: Early cerebritis, late cerebritis, early capsule, late capsule

Imaging Findings General Features (1) • Best diagnostic clue • Imaging varies with stages

Imaging Findings General Features (1) • Best diagnostic clue • Imaging varies with stages of abscess development • Early capsule: Well defined, thin-walled enhancing rim • Ring enhancing lesion with high signal on DWI • T 2 hypointense abscess rim with surrounding edema

Imaging Findings General Features (2) • Location • Typically supratentorial, but may occur infratentorial

Imaging Findings General Features (2) • Location • Typically supratentorial, but may occur infratentorial (up to 14 %) • Frontal and parietal lobes most common, graywhite junction (hematogenous) • Anterior and middle cerebral artery distribution • Size: Variable, 5 mm to several cm

Imaging Findings CT Findings: NECT • • Early cerebritis: Ill-defined hypodense subcortical lesion with

Imaging Findings CT Findings: NECT • • Early cerebritis: Ill-defined hypodense subcortical lesion with mass effect; may be normal early Late cerebritis: Central low density area; peripheral edema, mass effect increase Early capsule: Hypodense mass with moderate vasogenic edema and mass effect Late capsule: Edema, mass effect diminish

Imaging Findings CT Findings NECT CECT Early cerebritis CECT Late capsule Late cerebritis

Imaging Findings CT Findings NECT CECT Early cerebritis CECT Late capsule Late cerebritis

Imaging Findings CT Findings: CECT • • Early cerebritis: +/- Mild patchy enhancement Late

Imaging Findings CT Findings: CECT • • Early cerebritis: +/- Mild patchy enhancement Late cerebritis: Irregular peripheral rim enhancement Early capsule: Low density center with thin, distinct enhancing capsule (deep part is thinner, thickest near cortex) Late capsule: Cavity shrinks, capsule thickens • May be multiloculated and have daughter abscesses

Imaging Findings MR Findings: T 1 WI • • Early cerebritis: Poorly marginated, mixed

Imaging Findings MR Findings: T 1 WI • • Early cerebritis: Poorly marginated, mixed hypointense/isointense mass Late cerebritis: Hypointense center, isotense /mildly hyperintense rim Early capsule: Rim isointense to hyperintense to white matter; center hyperintense to CSF Late capsule: Cavity shrinks, capsule thickened

Imaging Findings MR Findings: T 2 WI • • • Early cerebritis: Ill-defined hyperintense

Imaging Findings MR Findings: T 2 WI • • • Early cerebritis: Ill-defined hyperintense mass Late cerebritis: Hyperintense center, hypointense rim; hyperintense edema Early capsule: Hypointense rim • Related to collagen, hemorrhage or paramagnetic free radicals • Late capsule: Edema and mass effect diminish

Imaging Findings MR Findings: DWI • • Increased signal intensity in cerebritis and abscess

Imaging Findings MR Findings: DWI • • Increased signal intensity in cerebritis and abscess ADC map: Markedly decreased signal centrally within abscess

Diffusion-weighted Imaging Brain Abscess Vs Tumor Necrotic or cystic tumors show low signal intensity

Diffusion-weighted Imaging Brain Abscess Vs Tumor Necrotic or cystic tumors show low signal intensity in diffusion-weighted imaging, indicating a high apparent diffusion coefficient (ADC). In contrast, in our study high signal intensity was observed in the abscess fluid, associated with low ADC

Imaging Findings MR Findings: T 1 C+ • • Early cerebritis: Patchy enhancement Late

Imaging Findings MR Findings: T 1 C+ • • Early cerebritis: Patchy enhancement Late cerebritis: Intense but irregular rim enhancement Early capsule: Well defined, thin-walled enhancing rim Late capsule: Cavity collapse, thickened enhancement of capsule • Capsule is thinnest on the ventricular side

Imaging Findings MR Findings: MRS • Central necrotic area may show presence of acetate,

Imaging Findings MR Findings: MRS • Central necrotic area may show presence of acetate, lactate, alanine, succinate, pyruvate, and amino acids

P. aeruginosae Infection MR Spectrometry T 2 WI T 1 WI C+ Inversion of

P. aeruginosae Infection MR Spectrometry T 2 WI T 1 WI C+ Inversion of AA, Lac, and alanine peaks and the suppression of lipid (L) components

Imaging Findings Resolving Abscess • • Hyperintense on T 2 WI, FLAIR; hypointense rim

Imaging Findings Resolving Abscess • • Hyperintense on T 2 WI, FLAIR; hypointense rim resolves Small ring/punctate enhancing focus may persist for month

Imaging Recommendation • • • Best diagnostic tool: Contrast-enhanced MR Protocol advice: Multiplanar MR

Imaging Recommendation • • • Best diagnostic tool: Contrast-enhanced MR Protocol advice: Multiplanar MR without and with contrast, DWI MRS may be helpful

Differential Diagnosis • • Primary or metastatic neoplasm Resolving hematoma Demyelination Subacute infarct

Differential Diagnosis • • Primary or metastatic neoplasm Resolving hematoma Demyelination Subacute infarct

Differential Diagnosis Primary or metastatic neoplasm • • Thick, nodular enhancing wall typical Low

Differential Diagnosis Primary or metastatic neoplasm • • Thick, nodular enhancing wall typical Low signal on DWI (occasionally high, can mimic abscess

Differential Diagnosis Resolving hematoma • • History of trauma or vascular lesion Blood products

Differential Diagnosis Resolving hematoma • • History of trauma or vascular lesion Blood products presents

Differential Diagnosis Demyelination • • • Enhancement often incomplete ring Characteristic lesions elsewhere in

Differential Diagnosis Demyelination • • • Enhancement often incomplete ring Characteristic lesions elsewhere in brain Small amount of mass effect for size of lesion

Differential Diagnosis Subacute infarct • • History of stroke Vascular distribution, gyriform enhancement

Differential Diagnosis Subacute infarct • • History of stroke Vascular distribution, gyriform enhancement

Etiology • • • Hematogenous from extracranial location (e. g. pulmonary infection, endocarditis, urinary

Etiology • • • Hematogenous from extracranial location (e. g. pulmonary infection, endocarditis, urinary tract infections) Direct extension from a calvarial or meningeal infection (Paranasal sinus, middle ear, teeth infections) Penetrating trauma Postoperative Right-to-left shunts (congenital cardiac malformations, pulmonary arteriovenous fistulas)

Cryptogenic • • 20~30% have no identifiable source Often polymicrobial (streptococci, staphylococci, anaerobes)

Cryptogenic • • 20~30% have no identifiable source Often polymicrobial (streptococci, staphylococci, anaerobes)

Epidemiology • • • Uncommon, approximately 2500 cases/year in U. S. Bacterial: Staphylococcus, Streptococcus,

Epidemiology • • • Uncommon, approximately 2500 cases/year in U. S. Bacterial: Staphylococcus, Streptococcus, Pneumococcus Diabetic: Klebsiella pneumoniae Posttransplant: Norcardia, Aspergillus, Candida AIDS: Toxoplasmosis, Mycobacterium Tuberculosis

Pathology Early Cerebritis • • • 3 to 5 days Infection is focal but

Pathology Early Cerebritis • • • 3 to 5 days Infection is focal but not localized Unencapsulated mass of PMNs, edema, scattered foci of necrosis and petechial hemorrhages

Pathology Late Cerebritis • • 4 ~ 5 days up to 2 weeks Necrotic

Pathology Late Cerebritis • • 4 ~ 5 days up to 2 weeks Necrotic foci coalesce Rim of inflammatory cells, macrophages, granulation tissue, fibroblasts surrounds central necrotic core Vascular proliferation, surrounding vasogenic edema

Peptostreptococcus-induced Brain Abscess HE stain Gram stain

Peptostreptococcus-induced Brain Abscess HE stain Gram stain

Pathology Early Capsule • • • Begins at around 2 weeks Well-delineated collagenous capsule

Pathology Early Capsule • • • Begins at around 2 weeks Well-delineated collagenous capsule Liquidified necrotic core, peripheral gliosis

Pathology Late Capsule • • • Weeks to months Central cavity shrinks Thick wall

Pathology Late Capsule • • • Weeks to months Central cavity shrinks Thick wall (collagen, granulation tissue, macrophages, gliosis)

Clinical Presentation • • Headache: the most common symptom Fever: 50% Other signs/symptoms: Seizures,

Clinical Presentation • • Headache: the most common symptom Fever: 50% Other signs/symptoms: Seizures, altered mental status, focal neurologic deficits Lab: Increased ESR (75%), elevated WBC count (50%)

Demographics • • • May occur at any age Most common during third and

Demographics • • • May occur at any age Most common during third and fourth decades, but 25% occur in patients < 15 years Gender: M: F = 2: 1

Treatment • • Surgical drainage and/or excision as the primary therapy Antibiotics only if

Treatment • • Surgical drainage and/or excision as the primary therapy Antibiotics only if small (< 2. 5 cm) or early phase of cerebritis Steroids to treat edema and mass effect Lumbar puncture hazardous, pathogen often can’t be determined from CSF

Empiric Antibiotic Therapy Primary or Contiguous Source • • • Streptococci (60~70%), bacteroides (20~40%),

Empiric Antibiotic Therapy Primary or Contiguous Source • • • Streptococci (60~70%), bacteroides (20~40%), Enterobacteriaceae (25~33%), S. aureus (10~15%) P Ceph 3 (cefotaxime 2 gm q 4 h IV or ceftriaxone 2 gm q 12 h IV) + metronidazole 7. 5 mg/kg q 6 h or 15 mg/kg q 12 h IV Alternative: Pen G 20~24 m. U IV qd + metronidazole

Empiric Antibiotic Therapy Post-surgical, Post-traumatic • • • S. aureus, Enterobacteriaceae Primary: Oxacillin 2

Empiric Antibiotic Therapy Post-surgical, Post-traumatic • • • S. aureus, Enterobacteriaceae Primary: Oxacillin 2 gm q 4 h IV + P Ceph 3 Alternative: Vancomycin 1 gm q 12 h IV + P Ceph 3

Empiric Antibiotic Therapy HIV-1 Infected (AIDS) • • • Toxoplasma gondii Pyrimethamine + salfadiazine

Empiric Antibiotic Therapy HIV-1 Infected (AIDS) • • • Toxoplasma gondii Pyrimethamine + salfadiazine + folinic acid Alternative: TMP/SMX

Complications • Inadequately or untreated abscesses • Intraventricular rupture, ventriculitis (may be fatal) •

Complications • Inadequately or untreated abscesses • Intraventricular rupture, ventriculitis (may be fatal) • • • Ventricular debris with irregular fluid level Hydrocephalus Ependymal enhancement typical • Meningitis, “daughter” lesions • Mass effect, herniation

Prognosis • • Stereotactic surgery + medical therapy have greatly reduce mortality Mortality: Variable,

Prognosis • • Stereotactic surgery + medical therapy have greatly reduce mortality Mortality: Variable, 0 ~ 30%