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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September 17, 2015
Listerial Rhombencephalitis
- Background: Listeriosis is a serious infection acquired by eating food contaminated with Listeria monocytogenes. This bacterium may be found in a variety of raw foods, such as uncooked meats, vegetables, and dairy products made from unpasteurized milk. The organism is a facultative, non-spore-forming, gram-positive bacillus. The risk of a healthy person developing listeriosis after eating contaminated food is very low.
- Listerial rhombencephalitis diagnosis is based on the clinical findings (cranial nerve dysfunction, ataxia, fever, headache, nausea and vomiting, coma, and hyporeflexia or hyperreflexia), blood culture, CSF analysis (pleocytosis), and MRI findings.
- Clinical Information: Rhombencephalitis by L. monocytogenes is a well-defined clinical entity characterized by progressive brain stem dysfunction. In humans, it occurs in 10% of all listeriosis cases. In autopsy series, it has been described as inflammatory infiltrates predominantly in lower cranial nerves nuclei.
- Imaging Findings:
- MR imaging may be crucial to the early diagnosis of this illness. Listerial infection shows predilection for the dorsal brain stem and cerebellum, specifically the floor of the fourth ventricle.
- Meningitis, cerebritis, and abscesses are seen, depending on the temporal evolution of the disease.
- DDx: Viral encephalitis, lymphoma, vasculitis (systemic lupus erythematosus, Behcet disease), sarcoidosis, tuberculosis, multiple sclerosis, and acute disseminated encephalomyelitis
- Viral encephalitis causes primarily a lymphocytic predominance in the CSF with negative blood cultures.
- Tuberculous meningitis can be distinguished by its primarily leptomeningeal involvement with low CSF glucose levels.
- Vasculitic and granulomatous diseases have associated systemic findings.
- In acute disseminated encephalomyelitis, lesions are mostly widespread, involving the subcortical hemispheric regions not restricted to the brain stem and cerebellum.
- Treatment was started before culture confirmation on the basis of clinical and MRI findings (ampicillin, cefotaxime, and gentamicin). Listeria rhombencephalitis results in considerably higher morbidity and a higher incidence of persistent neurologic impairment than simple meningitis.