An Atypical Presentation of Enteroviral Meningitis in an Immunocompetent Adult Man

Aseptic meningitis is inflammation of the meninges characterized by cerebrospinal fluid (CSF) pleocytosis and negative bacterial cultures. Viral infections are the most common cause, with enteroviruses (EV) accounting for the majority of cases worldwide. Typical presentations include fever, headache, and meningeal signs; however, atypical cases can occur, leading to diagnostic uncertainty. Early recognition and lumbar puncture (LP) are essential to avoid misdiagnosis. This case highlights an unusual presentation of enteroviral meningitis without fever or meningeal signs in an immunocompetent adult man. A 40-year-old man with a history of hypertension presented to the emergency department (ED) with a gradual-onset, severe headache, neck pain radiating to the scalp, mild nausea, and transient blurry vision. On examination, he was alert and oriented, afebrile, and in no acute distress. There was bilateral paraspinal tenderness but no nuchal rigidity or meningeal signs. Cardiovascular and neurologic examinations were unremarkable. Laboratory testing revealed mild leukocytosis and elevated liver enzymes. Brain and cervical spine imaging were unremarkable. LP showed clear CSF with an elevated opening pressure (26 mmHg), elevated protein (87 mg/dL), normal glucose (65 mg/dL), and mild pleocytosis. CSF Gram stain and cultures were negative. A meningitis-encephalitis polymerase chain reaction (PCR) panel was positive for EV but negative for bacterial and herpesviral pathogens, while a separate EV PCR was negative. The patient was started empirically on intravenous (IV) ceftriaxone, vancomycin, and acyclovir. Following confirmation of EV, antimicrobials and antivirals were discontinued, and supportive management with fluids, analgesics, and gastrointestinal prophylaxis was initiated. His symptoms resolved within 48 hours, and he was discharged in stable condition. This case demonstrates that enteroviral meningitis can present without fever, neck stiffness, or other meningeal signs, which may delay diagnosis. Classic meningeal signs have limited sensitivity, and their absence should not exclude meningitis in patients with persistent, severe headache. Additionally, the discordant PCR results emphasize that molecular assays are not infallible; repeat testing should be considered when clinical suspicion remains high. Recognition of atypical presentations is crucial to guide appropriate management. This case underscores that early LP and comprehensive diagnostic evaluation are essential when clinical findings are nonspecific. Maintaining a broad differential and relying on clinical judgment rather than physical signs alone can help prevent missed or delayed diagnoses.