Institute of Medical Science, University of Toronto, Toronto, ON, Canada Division of Brain, Imaging and Behaviour - Systems Neuroscience, Toronto Western Research Institute, Toronto, ON, Canada Department of Medical Imaging, University of Toronto, Toronto, ON, Canada Department of Medical Imaging, University Health Network, Toronto, ON, Canada Faculty of Dentistry, University of Toronto, Toronto, ON, Canada Mount Sinai Hospital Dental Clinic, Toronto, ON, Canada Department of Surgery, University of Toronto, Toronto, ON, Canada.
Pain. 2012 Jul;153(7):1467-1477. doi: 10.1016/j.pain.2012.04.003. Epub 2012 May 28.
Temporomandibular disorder (TMD) is a prevalent chronic pain disorder that remains poorly understood. Recent imaging studies reported functional and gray matter abnormalities in brain areas implicated in sensorimotor, modulatory, and cognitive function in TMD, but it is not known whether there are white matter (WM) abnormalities along the trigeminal nerve (CNV) or in the brain. Here, we used diffusion tensor imaging, and found that, compared to healthy controls, TMD patients had 1) lower fractional anisotropy (FA) in both CNVs; 2) a negative correlation between FA of the right CNV and pain duration; and 3) diffuse abnormalities in the microstructure of WM tracts related to sensory, motor, cognitive, and pain functions, with a highly significant focal abnormality in the corpus callosum. Using probabilistic tractography, we found that the corpus callosum in patients had a higher connection probability to the frontal pole, and a lower connection probability to the dorsolateral prefrontal cortex, compared to controls. Finally, we found that 1) FA in tracts adjacent to the ventrolateral prefrontal cortex and tracts coursing through the thalamus negatively correlated with pain intensity; 2) FA in the internal capsule negatively correlated with pain intensity and unpleasantness; and 3) decreases in brain FA were associated with increases in mean diffusivity and radial diffusivity, markers of inflammation and oedema. These data provide novel evidence for CNV microstructural abnormalities that may be caused by increased nociceptive activity, accompanied by abnormalities along central WM pathways in TMD.
颞下颌关节紊乱（TMD）是一种常见的慢性疼痛疾病，但仍未被充分了解。最近的影像学研究报告称，TMD 患者大脑中与感觉运动、调节和认知功能相关的区域存在功能和灰质异常，但尚不清楚三叉神经（CNV）或大脑中是否存在白质（WM）异常。在这里，我们使用弥散张量成像发现，与健康对照组相比，TMD 患者存在以下情况：1）双侧 CNV 的各向异性分数（FA）降低；2）右侧 CNV 的 FA 与疼痛持续时间呈负相关；3）与感觉、运动、认知和疼痛功能相关的 WM 束的微观结构存在弥散异常，胼胝体存在高度显著的局灶性异常。使用概率追踪，我们发现与对照组相比，患者的胼胝体与额极的连接概率更高，与背外侧前额叶皮质的连接概率更低。最后，我们发现：1）毗邻腹外侧前额叶皮质的束和穿过丘脑的束的 FA 与疼痛强度呈负相关；2）内囊的 FA 与疼痛强度和不愉快感呈负相关；3）大脑 FA 的降低与平均弥散度和径向弥散度的增加相关，这是炎症和水肿的标志物。这些数据为 CNV 微观结构异常提供了新的证据，这些异常可能是由于疼痛活动增加引起的，同时 TMD 中还存在中央 WM 通路的异常。
