Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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April 7, 2016
CNS Nocardiosis
- Background:
- Nocardia species are gram positive, strictly aerobic, catalase- and urease-positive bacilli.
- CNS Nocardia infection is rare, and its mortality rate is high.
- The infection is usually acquired through the respiratory tract or through the skin.
- This species has a tendency to spread from the primary site — usually the lungs — to the brain, kidney, joints, bones, and eyes. In the brain, the spread is usually through the choroid plexuses, and ventriculitis is a dominant feature.
- Clinical Presentation:
- Usually patients present late with variable neurologic symptoms.
- Key Diagnostic Features:
- Deep-seated ring-enhancing lesions are common.
- Ventriculitis and intraventricular debri may be seen when there is intraventricular or choroid plexus involvement.
- Differential Diagnosis:
- Tuberculomas: With caseation, profoundly low on T2WI
- Metastases: Usually at gray-white matter junction and rarely associated with ventriculitis; cystic metastases rarely show restricted diffusion in the absence of hemorrhage or high proteinaceous content.
- High-grade glioma: Rarely associated with ventriculitis; in gliomas, the solid component shows restricted diffusion due to the high cellularity.
- Treatment:
- Sulfonamide antibiotics are used empirically for the treatment.