SHM Converge Scientific Abstract ePoster Gallery-Beyond Respiratory Symptoms: Adult Influenza Encephalitis Presenting With Altered Mental Status

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This case report describes influenza-associated encephalitis (IAE), a rare but serious neurologic complication of influenza that is more commonly seen in children but can occur in adults. The authors present a previously healthy 43-year-old unvaccinated man who developed 3 days of fever, chills, myalgias, and cough, followed by 24 hours of worsening confusion and lethargy. On exam, he was febrile, tachycardic, obtunded, and mildly stiff in the neck without focal neurologic deficits.<br /><br />Workup showed influenza A positive by nasopharyngeal RT-PCR, mild leukopenia, elevated inflammatory markers, and mildly increased liver enzymes. Brain MRI demonstrated bilateral temporal lobe T2/FLAIR hyperintensities without hemorrhage. Cerebrospinal fluid analysis revealed lymphocytic pleocytosis, elevated protein, normal glucose, and influenza A RNA detected; HSV and VZV PCR were negative.<br /><br />He was treated in the ICU with IV peramivir, empiric acyclovir until herpes encephalitis was excluded, and supportive care. His mental status gradually improved, and he was transitioned to oral oseltamivir to complete a 10-day antiviral course. At 2-week follow-up, he had full neurologic recovery and improved MRI findings.<br /><br />The report emphasizes that IAE should be considered in influenza patients who develop acute neurologic symptoms, especially when respiratory symptoms are followed by rapid mental status decline. Diagnosis relies on high clinical suspicion, CSF studies, viral PCR testing, and MRI findings. Although there are no standardized adult treatment guidelines, early neuraminidase inhibitor therapy and supportive management may improve outcomes.

Asset Subtitle

Tina J. Kana

Meta Tag

Author List Christian Gabriele, Deniece Meñez, Hehui Quan, Rebecca Zeidman, Rujuta Patel, Stephen Maslak, Tina J. Kana, Umair Abbas

Category Clinical Vignettes

Concept Influenza-associated encephalitis

Concept Encephalitis

Concept Mental Status Change

Concept Viral Encephalitis

Concept Influenza

Distinguished Non-Finalist

Presenter Organization Lenox Hill Hospital

Presenting Author Tina J. Kana

Track Adult

Keywords

influenza-associated encephalitis

influenza A

adult encephalitis

neurologic complication

confusion

temporal lobe MRI

cerebrospinal fluid pleocytosis

peramivir

oseltamivir

viral PCR testing

Influenza-associated encephalitis

Encephalitis

Mental Status Change

Viral Encephalitis

Influenza