White matter brain and trigeminal nerve abnormalities in temporomandibular disorder.
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.
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.
Massieh
M
Moayedi
Irit
I
Weissman-Fogel
Tim Vaughn
TV
Salomons
Adrian Philip
AP
Crawley
Michael Brian
MB
Goldberg
Bruce Victor
BV
Freeman
Howard Charles
HC
Tenenbaum
Karen Deborah
KD
Davis
D000328:Adult; D016880:Anisotropy; D001921:Brain / Q000473:pathology / Q000503:physiopathology*; D038524:Diffusion Magnetic Resonance Imaging; D056324:Diffusion Tensor Imaging / Q000379:methods; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008875:Middle Aged; D011795:Surveys and Questionnaires; D013705:Temporomandibular Joint Disorders / Q000473:pathology / Q000503:physiopathology*; D014276:Trigeminal Nerve / Q000473:pathology / Q000503:physiopathology*