From acute stress syndrome to CNS infection: A case of HSV encephalitis with psychiatric mimicry.

RATIONALE: Herpes simplex virus type 1 (HSV-1) encephalitis is a rare but life-threatening central nervous system infection. Its early manifestations can mimic primary psychiatric disorders, which may delay recognition and treatment. We report a case where acute stress disorder masked underlying HSV-1 encephalitis.

PATIENT CONCERNS: A 47-year-old male patient presented with acute emotional distress, anxiety, sleep disturbance, and dissociative symptoms following the sudden death of his young niece.

DIAGNOSES: The patient initially fulfilled Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition criteria for acute stress disorder without neurological signs. During hospitalization, he developed fever, confusion, and disorientation. A computed tomography scan was initially interpreted as normal; however, subtle temporal lobe hypodensities were noted by a medical trainee. A subsequent magnetic resonance imaging revealed temporal lobe hyperintensities. cerebrospinal fluid analysis showed lymphocytic pleocytosis, and polymerase chain reaction confirmed HSV-1, establishing the diagnosis of HSV-1 encephalitis.

INTERVENTIONS: The patient was treated with intravenous acyclovir.

OUTCOMES: The patient's fever and psychiatric symptoms improved, and he was discharged in stable condition after completing a 7-day course of antiviral therapy. At a 1-month follow-up, he showed no neurological or psychiatric sequelae.

LESSONS: There are diagnostic challenges when psychiatric symptoms occur before neurological manifestations of HSV encephalitis. Clinicians should maintain a high index of suspicion for organic etiologies in atypical psychiatric presentations, and early neuroimaging and cerebrospinal fluid studies are essential to avoid delays in life-saving treatment.