Clinical characteristics and autonomic balance in patients with burning mouth syndrome: A retrospective chart review

This study aimed to identify the clinical characteristics of patients with burning mouth syndrome (BMS) according to the low frequency/high frequency (LF/HF) ratio in the heart rate variability test and to evaluate the potential of the LF/HF ratio as an indicator for the diagnostic or predictive assessment of patients with BMS. A total of 469 patients with BMS who visited the Oral Diseases Clinic of Kyung Hee University Korean Medicine Hospital between January 1, 2018, and December 31, 2022, were included in the study. The patients were asked to rate their tongue pain on a visual analog scale before and after treatment. Heart rate variability testing and measurement of the unstimulated and stimulated salivary flow rates were conducted. The patients were divided into 3 groups according to their LF/HF ratios. Clinical characteristics, including tongue pain, salivary secretion, and concomitant symptoms, were compared between the groups. Spearman correlation analysis was performed to determine any significant correlation between the LF/HF ratio and the clinical symptoms. The patients were also classified into 2 groups according to psychological factors to analyze their effects on the clinical characteristics of BMS. The pretreatment pain score (PRPS), posttreatment pain score (POPS), and incidence rate of dry mouth symptoms were higher in the parasympathetically activated group than in the other groups. Spearman correlation analysis revealed a negative correlation between the LF/HF ratio and the PRPS. The PRPS and POPS were higher and the unstimulated salivary flow rate, stimulated salivary flow rate, and LF/HF ratio were lower in the group with psychological factors than in the group without psychological factors. The parasympathetic group reported higher PRPS and POPS and a higher incidence of dry mouth symptoms. This may be attributable to the role of psychological factors in BMS, which is a functional pain disorder. The different clinical characteristics based on the LF/HF ratio indicate that the LF/HF ratio may serve as a significant indicator for diagnosing or predicting the prognosis of patients with BMS.