AUTONOMIC NERVOUS SYSTEM DYSREGULATION IN VASOVAGAL SYNCOPE: A FUNCTIONAL MRI STUDY

Abstract

Vasovagal syncope (VVS) represents a common form of transient loss of consciousness driven by aberrant autonomic regulation, yet the underlying neural mechanisms remain inadequately understood. This study employed resting-state functional magnetic resonance imaging (fMRI) to investigate autonomic nervous system dysregulation in individuals with a documented history of recurrent VVS, compared to matched healthy controls. Functional connectivity and amplitude of low-frequency fluctuation (ALFF) analyses were conducted across key brain regions implicated in autonomic and emotional regulation, including the amygdala, insula, hippocampus, anterior cingulate cortex (ACC), ventromedial prefrontal cortex (vmPFC), and posterior cingulate cortex (PCC). Based on the results, it appears that the vmPFC, ACC, and PCC are less engaged in VVS patients for regulating their autonomic functions.  It appears that increased connection between the insula and amygdala enhanced the ability to notice emotions and inner sensations.  The results from different regions indicated less ALFF and fractional ALFF in the VVS group than the control group, most clearly seen in the vmPFC and thalamus.  Besides, the researchers observed that ALFF and the number of faints were negatively related to brain activity in the vmPFC (r = -0.63) and ACC (r = -0.58).  Apparently, the brain networking involved in regulating arousal and emotions gets affected by VVS.  People are likely to experience more problems with reflex-induced fainting when the central region is not properly regulated.  These neurofunctional markers could help develop specialized treatments and predict diagnosis.  Using data from both the brain and body, as VVS does, brings greater attention to central processes in understanding patients’ symptoms.