Effects of Autogenic Training on Pain Modulation in Burning Mouth Syndrome: A Preliminary Study

Burning mouth syndrome (BMS) is a chronic pain condition lasting more than 3-6 months. While various pharmacological treatments are used, no definitive treatment exists. Autogenic training (AT), a relaxation technique, helps manage stress-related pain by influencing brain regions involved in emotion regulation and cognitive control. Reduced conditioned pain modulation (CPM) efficiency occurs in chronic pain conditions, and in BMS, higher state anxiety negatively impacts the descending pain modulation system. This study aimed to evaluate the effect of AT on spontaneous pain reduction in patients with BMS and determine if AT improves CPM, particularly in those with chronic BMS.

This study included 28 patients diagnosed with BMS, along with 17 healthy volunteers. Based on the duration the patients experienced the pain, those with BMS were categorized into subchronic (≤6 months) and chronic (>6 months) groups. All participants' temporal summation of pain (TSP), CPM, and pain intensity were recorded before and after the AT intervention. TSP was assessed through repeated electrical stimulation to the chin and was calculated as the difference between the visual analog scale scores after 10 electrical stimuli and the score following the first stimulus. CPM was calculated as the difference in TSP at baseline and following the conditioning of painful (47°C) or non-painful (40°C) stimuli applied to the non-dominant hand, serving as the conditioning stimulus (CS). This study was approved by the Ethical Committee of the Nihon University School of Dentistry (EP21D002) and conducted in accordance with the Declaration of Helsinki.

AT significantly reduced spontaneous pain in the chronic BMS group but not in the subchronic group. Furthermore, CPM improved only in patients with chronic BMS during painful stimuli, suggesting enhanced pain modulation. Correlation analysis between BMS duration and CPM revealed a negative correlation between painful CS CPM and disease duration (r = -0.411, p < 0.05), but no correlation when the CS was not painful.

AT can reduce pain in patients with chronic BMS (lasting more than six months) at least partly by enhancing the patients' pain modulation and emotional regulation, making it a potential adjunctive therapy for chronic cases.