Table 1 Summary of functional MRI studies on TMD, MRI techniques including rs-fMRI, ts-fMRI, ASL, and MRS
Studies | Modality | Analysis method | Patients | Controls | Main findings in TMD patients compared to HC | ||||
|---|---|---|---|---|---|---|---|---|---|
Characteristics | Number and agea | Durationa | Medication (n) | Clinical assessments | Number and agea | ||||
rs-fMRI (n = 4) | |||||||||
Kucyi et al. [46] | rs-fMRI | Voxel-wise FC | TMD (RDC/TMD) | 17F; 33.1 ± 11.9 y | 9.3 ± 8.3 (0.75–30) y | 8 | NPS1, Pain Catastrophizing Scale [44] | 17F; 32.2 ± 10.2 y | In TMD: • Increased mPFC FC with other DMN regions, including PCC/PCu, retrosplenial cortex and areas within visual cortex • Pain rumination scores positively correlated to mPFC FC with the PCC/PCu, retrosplenial cortex, medial thalamus and PAG |
He et al. [47] | rs-fMRI | Whole brain fALFF | TMD (RDC/TMD) | 9M, 14F; 22.4 ± 3.6 y; 11/23 received 3-month splint therapy | 14.8 ± 20.7 months | 0 | SCL-90, GCPS [83], Helkimo indices [78], CR–MI discrepancy index [76] | 9M, 11F; 23.1 ± 2.4 y | In TMD: • Decreased fALFF in left precentral gyrus, SMA, middle frontal gyrus, and right OFC • Negative correlation between fALFF in left precentral gyrus and vertical CR-MI discrepancy • Improved symptoms and signs after treatment, with increased fALFF in left precentral gyrus and left posterior insula compared with pretreatment |
He et al. [48] | rs-fMRI | Voxel-wise FC | TMD (RDC/TMD) | 11M, 19F; 22.1 ± 3.8 (15–29) y; 16/30 had myofascial pain | 17.3 ± 22.4 months | 0 | 9M, 11F; 23.1 ± 2.4 (20–30) y | In TMD: • Decreased FC in ventral corticostriatal circuitry, between ventral striatum and ventral frontal cortices, including ACC and anterior IC • Decreased FC in dorsal corticostriatal circuitry, between dorsal striatum and dorsal cortices, including precentral gyrus and supramarginal gyrus • Decreased FC within striatum • Decreased corticostriatal FC correlated with clinical measurements including Di and pain intensity | |
Zhang et al. [49] | rs-fMRI | ReHo and voxel-wise FC | TMD synovitis (RDC/TMD) | 8F; 33.5 ± 8.7 y | NA | 0 | VAS2 | 10F; 33.9 ± 7.3 y | In TMD: • Decreased regional homogeneity in right anterior IC • Decreased positive FC between right anterior IC and MCC • Decreased negative FC between right anterior IC and the precuneus |
ts-fMRI (n = 9) | |||||||||
Nebel et al. [52] | ts-fMRI | Brain activation | TMD (RDC/TMD) | 13F; 28.7 ± 7.6 y | NA | NA | SF-MPQ [33] | 12F; 28.8 ± 7.9 y | In TMD: • Distinct subregions of contralateral S1, S2 and IC responded maximally for TMD and HC • Primary auditory cortex activation • Greater activations bilaterally in ACC and contralaterally in the amygdala |
Ichesco et al. [51] | rs-fMRI and ts-fMRI | Voxel-wise FC | Myofascial TMD (RDC/TMD) | 8F; 23–31 y | NA | NAb | 8F; 22–27 y | In TMD: • Increased FC between left anterior IC and pgACC during both resting state and applied pressure pain • Negative correlation between anterior IC-ACC connectivity and clinical pain intensity by VAS | |
Wessman et al. [54] | ts-fMRI | Brain activation and ROI-wise FC | TMD (RDC/TMD) | 17F; 35.2 ± 11.6 y | 9.3 ± 8.3 (0.75–30) y | 8 | NRS3 | 17F; 34 ± 9.9 y | In TMD: • Slow reaction times for all Stroop tasks • Increased task-evoked responses in brain areas implicated in attention (lateral prefrontal, inferior parietal), emotional processes (amygdala, pgACC), motor planning and performance (SMA and M1), and activations of the DMN (mPFC and PCC) • Decreased FC between prefrontal and cingulate cortices and between amygdala and cingulate cortex |
Zhao et al. [53] | ts-fMRI | Brain activation | TMD synovitis with unilateral biting pain (RDC/TMD) | 3M, 11F; 33.7 ± 13.2 y; contralateral (n = 8) and ipsilateral (n = 6) TMD biting pain | NA | NA | VAS2, SCL-90 | 7M, 7F; 23.7 ± 0.9 y | TMJ synovitis patients with contralateral or ipsilateral biting pain showed activations in inferior frontal gyrus, superior temporal gyrus, medium frontal gyrus, M1, and ACC; of these ACC was not activated in HC |
Gustin et al. [50] | ts-fMRI; DTI; ASL | Brain activation, FA, and CBF | TMD (RDC/TMD) | 4M, 13F; 44 ± 3 y | 10.7 ± 2.9 y | 13 | VAS2, MPQ [36] | 26M, 27F; 41 ± 2 y | Positive results for PTN patients, but not TMD: • Showed S1 functional reorganization • Showed reduced CBF in contralateral S1 • Showed decreased FA in contralateral S1 |
Lickteig et al. [60] | ts-fMRI | Brain activation | TMD (RDC/TMD) | 1M, 13F; 25.7 ± 8.7 (21–53) y | NA | NA | GCPS [83], Mandibular Function Impairment Questionnaire [131] | No control group | In TMD: • Subjective pain ratings decreased, and symmetry of condylar movements increased during therapy • fMRI during occlusion showed activation decrease in right anterior IC and right cerebellum during therapy • Correlation analysis between pain score and fMRI activation decrease identified right anterior IC, left posterior IC, and left cerebellar hemisphere • Left cerebellar and right M1 activation magnitude negatively associated with symmetry of the condylar movements |
He et al. [57] | ts-fMRI | Brain activation | TMD (RDC/TMD) | 11M, 19F; 22.1 ± 3.8 (15–29) y; 16/30 with myofascial pain | 17.3 ± 22.4 months | 0 | 9M, 11F; 23.1 ± 2.4 (20–30) y | • TMD showed decreased positive activity in left M1, right and left inferior temporal gyrus, and left cerebellum, and increased negative activations in the right mPFC during teeth clench • For the 11 TMD after splint treatment, these areas returned to normal neural activity | |
Harper et al. [56] | ts-fMRI | Brain activation | Myofascial TMD (RDC/TMD) | 1M, 9F; 24.9 ± 1.2 y | 2.3 ± 2.0 y | NAb | VAS2, SF-MPQ [33] | 10F; 26.9 ± 4.4 y | • SVM could determine location of pain evoked from pressure on temporalis and thumb in TMD, but not in HC • Differences in TMD included decreased responses to temporalis-evoked pain in the left OFC, ACC, and operculum • No significant difference in pain-evoked BOLD response for a location remote from the TMJ (the thumb) |
Roy et al. [55] | ts-fMRI | Brain activation | TMD with jaw pain (TMD pain screening questionnaire [132]) | 6M, 10F; 36.56 (18–68) y | ≥ 6 months | NA | GCPS [83], VAS2 | 6M, 9F; 30.5 (18–58) y | • For controlled grip-force task, SVM separated the groups according to the functional activity in regions including the PFC, IC, and thalamus • For controlled pain-eliciting stimulus on forearm, SVM separated the groups according to functional activity in brain regions including dlPFC, rostral ventral premotor cortex, and inferior parietal lobule |
ASL and MRS (n = 3) | |||||||||
Gerstner et al. [58] | MRS | Metabolite levels | Myofascial TMD (RDC/TMD) | 1M, 10F; 25.8 ± 2.33 y | 6 months to 7 years | NAb | 1M, 10F; 24.8 ± 1.2 y | • Glu levels lower in all individuals after pain testing • In TMD: - Left-insular Gln levels were related to reported pain - Left posterior insular NAA and Cho levels higher at baseline - Left insular NAA levels positively correlated with pain symptom duration | |
Youssef et al. [23] | ASL | CBF and brain stem blood flow | TMD (RDC/TMD) | 3M, 12F; mean ± SEM, 44.9 ± 3.1 (25–67) y | 11.4 ± 3.3 y | 5 | VAS2, MPQ [36] | 13M, 41F; mean ± SEM, 46.9 ± 2.1 (20–80) y | • TNP had CBF decreases in several regions, including thalamus, S1 and cerebellar cortices • TMD had CBF increases in regions associated with higher-order cognitive and emotional functions, such as ACC, dlPFC and precuneus • In TMD, blood flow increased in motor-related regions and within spinal trigeminal nucleus |
Harfeldt et al. [59] | MRS | Metabolite levels | rTMD and gTMD (DC/TMD) | rTMD: 17F, median age, 40 (30–44) y; gTMD: 19F, median age, 43 (40–56) y | ≥3 months | NA | NRS3 | 10F; median age, 36 (26–51) y | • Only tCr level was higher in TMD than HC • Cho negatively correlated to maximum mouth opening capacity with or without pain, as well as PPT at the hand • Glu positively correlated to temporal summation and the rTMD and gTMD pain groups showed more pronounced temporal summation • gTMD pain group had lower PPT than rTMD |