Department of Dentistry and Oral Health, Aarhus University, Aarhus C, 8000, Denmark; Scandinavian Center for Orofacial Neurosciences (SCON), Denmark; Hammel Neurorehabilitation and University Research Clinic, Hammel, 8450, Denmark.
Department of Dentistry and Oral Health, Aarhus University, Aarhus C, 8000, Denmark; Scandinavian Center for Orofacial Neurosciences (SCON), Denmark.
Brain Stimul. 2020 May-Jun;13(3):554-561. doi: 10.1016/j.brs.2020.01.001. Epub 2020 Jan 8.
Chronic orofacial pain (COP) patients often perceive the painful face area as "swollen" without clinical signs; such self-reported illusions of the face are termed perceptual distortion (PD). The pathophysiological mechanisms underlying PD remain elusive.
To test the neuromodulatory effect of repetitive transcranial magnetic stimulation (rTMS) on PD in healthy individuals, to gain insight into the cortical mechanisms underlying PD.
PD was induced experimentally by injections of local anesthetic (LA) around the infraorbital nerve and measured as perceived size changes of the affected area. Participants were randomly allocated to inhibitory rTMS (n = 26) or sham rTMS (n = 26) group. The participants rated PD at baseline, 6 min after LA, immediately, 20 and 40 min after rTMS. The rTMS (inhibitory and sham) was applied to face (lip) representation area of primary somatosensory cortex (SI) as an intervention at 10 min after the LA, when the magnitude of PD is large. As inhibitory rTMS, continuous theta-burst stimulation paradigm (50 Hz) for 40s was employed to inhibit cortical activity.
We demonstrated a significant decrease in the magnitude of PD immediately and 20 min after the application of inhibitory rTMS compared with sham rTMS (P < 0.006). In two control experiments, we also showed that peripheral muscle stimulation and stimulation of a cortical region other than the lip representation area had no effect on the magnitude of the PD.
Inhibitory rTMS applied to a somatotopical-relevant cortical region modulates PD of the face in healthy individuals and could potentially have therapeutic implications for COP patients.
慢性面痛（COP）患者常对面部疼痛区域感到“肿胀”，但无临床体征；这种对面部的自我报告幻觉称为知觉扭曲（PD）。PD 的病理生理机制仍不清楚。
测试重复经颅磁刺激（rTMS）对健康个体 PD 的神经调节作用，深入了解 PD 的皮质机制。
通过眶下神经周围局部麻醉（LA）注射诱导 PD，并测量受影响区域的感知大小变化。参与者被随机分配到抑制性 rTMS（n=26）或假刺激 rTMS（n=26）组。参与者在基线、LA 后 6 分钟、rTMS 后即刻、20 分钟和 40 分钟时评估 PD。在 LA 后 10 分钟，当 PD 程度较大时，将 rTMS（抑制性和假刺激）应用于初级体感皮层（SI）的面部（唇）代表区作为干预措施。作为抑制性 rTMS，采用连续 theta 爆发刺激模式（50 Hz）持续 40 秒以抑制皮质活动。
与假刺激 rTMS 相比，我们发现抑制性 rTMS 应用后即刻和 20 分钟 PD 的幅度明显降低（P<0.006）。在两个对照实验中，我们还表明，外周肌肉刺激和刺激唇代表区以外的皮质区域对面部 PD 的幅度没有影响。
应用于躯体相关皮质区域的抑制性 rTMS 可调节健康个体面部的 PD，并可能对 COP 患者具有治疗意义。
