RESUMEN
Introduction: Herpes simplex virus (HSV) is associated with one of the lethal diseases, Herpes simplex encephalitis (HSE). Diagnosis is confirmed using MRI and CT scan imaging techniques and more sensitive DNA PCR from cerebrospinal fluid analysis and brain biopsy.Case presentation: However, after four days, the patient's HSE diagnosis was confirmed by the detection of herpes simplex virus type 1 (HSV1) via polymerase chain reaction (PCR) testing. This case highlights the importance of utilizing multiple diagnostic aids and not solely relying on initial test results, as infections may not appear in CSF analysis or MRI scans initially. Furthermore, this case also emphasizes the necessity of initiating empirical treatment based on clinical signs and symptoms, even in cases where diagnostic tests initially appear negative. Prompt and efficient diagnosis and treatment are crucial in managing HSE and preventing long-term neurological damage.Conclusion: This case of HSE underscores the significance of a multifaceted diagnostic approach and timely intervention in managing this potentially severe and life-threatening condition. As mentioned, sometimes the infection does not appear in CSF analysis initially, nor does its effects appear in MRI. HSV PCR remains the golden test to confirm the diagnosis of HSE.