(391) Concurrent HSV1-VZV Encephalitis: A Diagnostic Enigma

Introduction: Herpes Simplex (HSV) and Varicella Zoster (VZV) can independently induce meningitis and encephalitis. Concurrent central nervous system infection by both viruses has not been previously reported; we report the first concurrent HSV-1 and VZV encephalitis case who presented with Epilepsia partialis continua (EPC).

Methods: NA

Results: A 55-year-old female with a history of stroke, GAD antibody-associated spinocerebellar ataxia, and seizure disorder presented from a nursing home with seizures and concern for recurrent sepsis. She had recently been discharged from the hospital after treatment for sepsis secondary to bacteremia and fungemia.

Given her poor neurologic exam, a CT head was performed, revealing prominent hydrocephalus suggestive of cerebral edema with right subdural hemorrhage. This prompted an external ventricular drain (EVD) placement and cerebrospinal fluid (CSF) analysis revealed WBC 7, protein 52, and positive PCR for VZV and HSV. EEG revealed severe diffuse encephalopathy with ictal potential and progressive epileptogenicity concerning for EPC. MRI revealed diffuse bilateral vasogenic edema with predominant T2 hyperintensities in bilateral cerebral hemispheres and the inferior cerebellar hemispheres. MRA was unremarkable.

She received high-dose acyclovir, antiepileptics, and steroids. She had worsening cerebral edema with uncal herniation, needing aggressive medical therapy for intracranial hypertension (ICH) and CSF drainage. Subsequent imaging showed increased hemorrhagic transformation in both cerebral hemispheres prominent in bilateral frontal and right parietal regions. Given her coagulopathy, she developed tract hemorrhages from the EVDs. Despite aggressive treatment of encephalitis, ICH, and EPC, she demonstrated no neurological improvement and was discharged to a facility. Two months later, she expired after a cardiac arrest.

Conclusions: This first documented case of concurrent HSV-1 and VZV encephalitis highlights the need for heightened awareness in patients with complex medical histories, particularly in the context of polymicrobial sepsis. Early diagnosis and targeted therapy are crucial for optimal patient outcomes. Furthermore, the sepsis etiologies necessitate integrated, epidemiology-informed screening to identify and manage atypical encephalitis accurately.