#idboardreview 65 F no PMH p/w fever, headache x2d, winter, brought by family as not acting like herself, hyperactive, animated movements. No animals, no outdoor activities, not sexually active. Diagnosis? #medEd #IDMedEd 
Herpes simplex #HSV encephalitis is most common acute sporadic focal encephalitis in USA (1-2cases/1 million persons/yr. 1º infection or by reactivation of latent virus. In case of 1º oropharyngeal disease, spread along olfactory or trigeminal nerve has been hypothesized
other neuronal pathways may be involved in reactivation of latent virus. Infection or reactivation leads to focal inflammation, often in the temporal lobe, with associated neurologic deficits.
Acute #HSV encephalitis: fever & focal neurologic abnormalities; seizures are common. Meningitis may occur. CSF typicallylymphocytic predominance with ⬆️protein level, may ⬆️rbc. In rare cases, intracranial hemorrhage is part of the initial presentation or a later complication.
Brain MRI may show inflammation, edema, or mass effect in an asymmetric pattern, & temporal-lobe involvement is common. Typical EEG periodic lateralizing epileptiform discharges or focal slowing, often localized to the temporal lobe. Fig:Infections of CNS scheld 4th Ed
Cases throughout the year: biphasic 5-30 yo & >50 yo. #HSV1 causes 95% cases. Most sensitive non-invasive test csf PCR (may initially be negative but becomes positive on or after day 4)
#hsv encephalitis Clinical suspicion: empiric iv acyclovir 30mg/kg/d 14-21d. Even w/treatment: neurological sequelae are frequent in pts>35yo
