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Young female with neurological deterioration

Differential Diagnosis

Infection i.e. abscess

Demylenating disease i.e. MS, ADEM

Primary Tumor

Resolving Hematoma

Subacute Infarct

ABSCESS IMAGING FINDINGS

VARY WITH STAGE OF ABSCESS DEVELOPMENT

CT- EARLY CEREBRITIS: ILL DEFINED CORTICAL LESION WITH MASS EFFECT +/- PATCHY ENHANCEMENT

- LATE CEREBRITIS: CENTRAL LOW DENSITY AREA WITH MASS EFFECT, EDEMA AND AN IRREGULAR RIM WITH PERIPHERAL ENHANCEMENT

- EARLY CAPSULE: HYPODENSE CENTER WITH ENHANCEMENT, DEEP PART OF CAPSULE THINNEST.

- LATE CAPSULE: CAVITY SHRINKS, CAPSULE THICKENS, MAY SHOW MULTILOCULATION OR HAVE DAUGHTER LESIONS

ABSCESS IMAGING FINDINGS

MRI

T1 EC- POORLY MARGINATED MIXED HYPO/ISOINTENSE REGIONS

LC- HYPOINTENSE CENTER, ISO/HYPERINTENSE (MILD) RING

ECp- RIM ISO/HYPERINTENSE TO WM CENTER HYPERINTENSE TO CSF

LCp- CAVITY SHRINKS AND CAPSULE THICKENS

ABSCESS IMAGING FINDINGS

MRI T2

EC: ILL-DEFINED HYPERINTENSE MASS

LC: HYPERINTENSE CENTER HYPOINTENSE RIM,HYPERINTENSE EDEMA

ECp: HYPOINTENSE RIM-RELATED TO COLLAGEN,HEMORRHAGE, OR PARAMAGNETIC FREE RADICALS

LCp: EDEMA AND MASS EFFECT DIMINISHED

ABSCESS IMAGING FINDINGS

DWI: INCREASED SIGNAL IN CEREBRITIS ABCESS, ADC SHOWS HYPODENSITY CENTRALLY WITHIN ABCESS. (RESTRICTED DIFFUSION)

T1+C: EC- PATCHY ENHANCEMENT

LC- INTENSE BUT IRREGULAR RIM ENHANCEMENT

ECp- WELL DEFINED THIN WALLED ENHANCING RIM

LCp- CAVITY COLLAPSES,THICKENED ENHANCEMENT OF CAPSULE, CAPSULE THINNEST ON VENTRICULAR SIDE

Pathology

Cerebritis- unencapsulated region of vessels, inflammatory cells, and edema that gradually coalesce

Capsule develops around necrotic core as abscess matures

Etiology

Hematogenous from extracranial location

Direct extension from calvarial or meningeal infection (teeth, sinuses, middle ear)

Right to left shunts cardiac malformations, pulmonary av fistulas

20-30% cryptogenic –no definable source

Pathology

EARLY CEREBRITIS 3-5 days. focal infection PMNs, edema, scattered necrosis and petechial hemorrhage

LATE CEREBRITIS 4/5days -2 weeks. Necrosis coalesces and rim of inflammatory cells, macrophages, granulation tissue, fibroblasts surround central necrotic core

EARLY CAPSULE 2 weeks. well delineated collagen capsule surrounding liquefied core with peripheral gliosis.

LATE CAPSULE weeks to months. central cavity shrinks wall has thickened composed of collagen, granulation tissue, and fibroblasts

CLINICAL PRESENTATION

HEADACHE 90%

FEVER 50%

ALSO CAN PRESENT WITH SEIZURES, ALTERED MENTAL STATUS, FOCAL NEUROLOGICAL DEFECTS

COMPLICATIONS

INTRAVENTRICULAR RUPTURE WITH VENTRICULITIS

HYDROCEPHALUS

MENINGITIS

LOCALIZED VENOUS THROMBOSIS

IMAGING PEARLS

ASSOCIATED LOCAL CAUSE IE SINUSITUS, OTITIS MEDIA, MASTOIDITIS

EARLY CAPSULE THIN WALLED,WELL DEFINED ENHANCING RIM, CAPSULE THINNEST ON VENTRICULAR SIDE

RESTRICTED DIFFUSION

T2 HYPOINTENSE RIM RESOLVES BEFORE ENHANCEMENT IN SUCCESSFULLY TREATED PATIENTS