Rapid Neuromodulation of Central Sensitization in Fibromyalgia and Myofascial Pain Syndrome: Evidence for Real-Time Pain Gate Control via Mandibular Repositioning

Purpose: To document a phenomenon of rapid and widespread pain elimination in patients with myofascial pain syndrome (MPS) and fibromyalgia (FM) following precise mandibular repositioning, and to propose a mechanism of real-time neuromodulation via the mesencephalic trigeminal nucleus (Me5) that challenges the conventional neuroplasticity model. Methods: Following a preliminary study of 79 patients, the appropriate mandibular position (Vanishing Position: VP) was defined by the disappearance of tenderness in the lateral pterygoid and obliquus capitis inferior muscles. 21 patients (including 5 with FM) participated in a double-blind, crossover trial. The therapeutic effect was evaluated using a visual analog scale (VAS) at the most painful distant sites following 5-minute intervals of a placebo (palatal plate) and a positioning splint (P-splint). Results: The P-splint induced a profound and immediate reduction in VAS scores. On Day 2, VAS scores decreased significantly more with the P-splint (MPS: 1.1±0.9; FM: 2.0±2.2) compared to the placebo (MPS: 3.4±2.4; FM: 4.9±2.9) and baseline. Conclusion: The immediacy of systemic pain relief suggests a dynamic, brainstem-mediated pain gate control. Afferent inputs from the stomatognathic system likely act as a master switch for the descending pain modulatory system.