ASSOCIATION OF SMALL RIGHT VAGUS NERVE CROSS-SECTIONAL AREA WITH ABNORMAL HEART RATE VARIABILITY

초록

Background: In Parkinson's disease (PD), autonomic dysfunction occurs throughout the disease course. The vagus nerve is a crucial component of the autonomic nervous system. Cardiac autonomic dysfunction is present in the early stage of PD. The cross-sectional area (CSA) of the vagus nerve, measured by ultrasound, is significantly reduced in PD patients. We aimed to investigate the association between vagus nerve CSA measured by ultrasound and autonomic function in patients with early PD. Methods: We investigated 104 individuals (74 early PD patients and 30 healthy individuals). The vagus nerve CSA was measured using nerve ultrasound at the bilateral mid-cervical area, and CSA was compared between the patients and healthy controls. In 74 patients, additional investigation was conducted: thorough history taking, scales, autonomic function tests (including heart rate variability (HRV), valsalva ratio) and Cross-Cultural Smell Identification Test. Patients were divided into two groups according to median of the right and left vagus nerve CSA, and the association between the test results and CSA was analyzed. Results: The vagus CSA in the patient group was smaller than that in the control group on both sides, with the left side being smaller than the right. In the patient group, the median age was 64.5 years, with 43 males (58.1%). In right side, 33 were larger than the median (1.30 mm2) and 41 were smaller. In left side, 38 were larger than the median (1.20 mm2). Smaller right vagus CSA was significantly associated with abnormal HRV (odds ratio 3.17, p-value = 0.027) and left vagus CSA was not significant. Conclusions: There is a significant association between small right vagus nerve CSA and abnormal HRV. Our findings support previous studies which have suggested that the right vagus nerve may play a more role in parasympathetic cardiac function compared to the left one.