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Encephalitis
From WikEM
Contents
Background
- Infection of brain parenchyma of the temporal lobes and inferior frontal lobe causing distinct neurologic abnormality
- Pathophysiology
- Gray matter is predominantly affected (cognitive / psychiatric signs, lethargy, seizure)
Microbiology
Clinical Features
- New psychiatric symptoms (HSV)[1]
- Cognitive deficits
- Aphasia, amnesia, confusion
- Seizure
- Movement disorder (arboviruses)
- Fever and meningeal signs are almost always present
- Dysuria and pyuria (St. Louis encephalitis)
- Extreme lethargy (West Nile encephalitis)
Differential Diagnosis
- SAH
- Lyme disease
- Brain abscess
- Bacterial endocarditis
- Toxic / metabolic encephalopathy
Altered mental status and fever
- Infectious
- Sepsis
- Meningitis
- Encephalitis
- Cerebral malaria
- Other
Evaluation
- Imaging identifies abnormalities in medial temporal and inferior frontal gray matter in HSV[2]
- CT Head - edema and petechial hemorrhage
- MRI - increased T2 intensity
- LP
- Bloody tap consistent with HSV
Management
often it is unclear which type of encephalitis is present and starting Acyclovir empirically is appropriate
HSV encephalitis
- Acyclovir 10mg/kg every 8hrs
HZV encephalitis
- Acyclovir 10mg/kg every 8hr
CMV encephalitis
- Ganciclovir 5mg/kg IV every 12hr OR
- Foscarnet 90mg/kg IV every 12 hrs
Disposition
Admit in all cases
See Also
References
- ↑ Loring KE, Tintinalli JE: Central Nervous System and Spinal Infections, in Tintinalli JE, Kelen GD, Stapczynski JS (eds): Emergency Medicine, A Comprehensive Study Guide, ed 7. New York, McGraw-Hill, 2011, (Ch) 168:p 1175-1176.
- ↑ Howes DS et al. Encephalitis Workup. Oct 12, 2015. http://emedicine.medscape.com/article/791896-workup#showall
