Clinical diagnostic challenge of a sudden coma patient under the cover of influenza B: a case report and literature review

Background: Coma is a medical emergency that necessitates prompt clinical intervention, and early identification of its underlying etiology is pivotal for prognosis. However, sometimes discerning the etiology of coma proves challenging, particularly when compounded by other medical conditions. We report a clinical diagnostic challenge encountered in a patient experiencing sudden coma concurrent with influenza B infection.Case presentation: We present the clinical diagnostic process for the sudden onset of coma in a 27-year-old male patient with influenza B. The patient did not improve, despite receiving antiviral therapy and general antibiotic treatment. Ultimately, the patient was diagnosed with infective endocarditis (IE) complicated by cerebral infarction, after mitral and aortic valve replacement, the patient was stable and discharged.Conclusions: This case highlights that emergency physicians and nonspecialists should improve their understanding of the uncommon causes of coma. Clinicians should consider the possibility of endocarditis when fever and cerebral infarction persist despite standard anti-inflammatory therapy, and the necessity of timely surgery for patients with congenital valvular heart disease. In addition, we recognize the potential of microbial molecular diagnostic techniques in managing endocarditis.