[When the Brain Dictates the Rhythm].

Introduction: In rare cases, an HSV-Encephalitis can lead to sinus node dysfunction, as was the case in this 70-year old woman who suffered from recurrent syncopes. Diagnostic work-up showed sinus bradycardias and short-lasting sinus arrests, primarily consider-ed to be of cardiac etiology. After development of fever and neurological alteration, an HSV1 encephalitis was diagnosed. As our research of the current literature showed, the connection between the two is not completely clear. The HSVtypical infestation of the insular cortex, which influences the autonomic nervous system, should be discussed by all means. However, due to cessation of arrhythmia after seizure-suppressing therapy, we suspected an epileptic cause in this case. This shows the importance of a thorough differential diagnostic evaluation.