Fact-sheet: Encephalitis
Updated on 09/17/2021 at 12:16 PM
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Definition
Subacute presentation (1 day to 12 weeks). Etiologies: *Mainly paraneoplastic (bronchial, testicular, breast, parotid, ovarian, colon, kidney, thymoma cancer...) *Immunologic: VGKC antibodies, Hashimoto, Sjögren, Lupus, antibodies directed against hippocampal neuropil *Infectious: HSV1, VZV, EBV, HHV6, syphilis, HIV *Metabolic: alcoholism, vitamin B1 deficiency, anoxia, Cushing syndrome, low blood glucose Hypoglycemia *Vascular *Toxic: aluminum, Remicade® (direct or immune-mediated?) *Neoplastic
Clinical features
Mode of presentation:
*anterograde memory impairment
*confusion that may progress to dementia
*seizures that may precede cognitive impairment by several months (temporal and psychomotor, generalized tonic-clonic)
*behavioral changes, personality changes, and psychiatric symptoms
*sleep disturbance (hypersomnia or insomnia, narcolepsy, cataplexy)
*eating disorders
MRI
20% of limbic encephalitis cases are of paraneoplastic origin.
In limbic encephalitis, MRI shows T2 FLAIR hyperintensity of the mesial temporal lobe in 80% of cases
*Unilateral or bilateral
*With or without contrast enhancement
*Extralimbic involvement sometimes found: midbrain, cerebellum, fronto-temporal lobes
Nuclear medicine
For paraneoplastic limbic encephalitis:
FDG-PET is useful in patients with normal EEG and MRI (hypermetabolism in the temporal lobes, midbrain, cerebellum, or fronto-temporal lobes)