Table 2 Summary of structural MRI studies on TMD, MRI techniques including sMRI and DTI

Younger et al. [31]

3D T1

Whole brain VBM

Myofascial TMD

(RDC/TMD)

14F; 38 ± 13.7 (23–61) y

4.4 ± 2.9 (1–11) y

9

NRS³

15F, individually age-matched to patients

• No overall difference in GMV between TMD and HC

• In TMD:

- Decreased or increased GMV in several areas of trigemino-thalamo-cortical pathway, including brainstem trigeminal sensory nuclei, thalamus and S1

- Increased GMV in limbic regions such as posterior putamen, globus pallidus, and anterior IC

- Self-reported pain severity was associated with increased GMV in pgACC and PCC

Gerstner et al. [32]

3D T1

Whole brain VBM

Myofascial TMD (RDC/TMD)

9F; 25.4 ± 2.5 (23–31) y

2.5 ± 2.1 (0.5–4) y

NA**

VAS², SF-MPQ [33], STPI [34]

9F; 24.8 ± 1.4 (24–27) y

• No differences in global GMV or WMV

• In TMD:

- Decreased GMV in left ACC, right PCC, right anterior IC, left inferior frontal gyrus, and superior temporal gyrus

- Decreased regional WMV in medial prefrontal cortex bilaterally

Gustin et al. [35]

3D T1 and MRS

Whole brain VBM and metabolite levels

TMD (RDC/TMD)

4M, 16F; mean ± SEM, 45.7 ± 2.9 (28–70) y

11.4 ± 3.3 y

14

VAS², MPQ [36], BDI [37], STATE [38]

6M, 25F; mean ± SEM, 46.8 ± 3.3 (21–87) y

• VBM revealed no change in regional GMV in TMD compared to HC, while TNP had significant regional GMV changes in a number of brain regions

• No significant change in NAA/Cr in thalami of TMD compared with HC, while NAA/Cr was decreased in the thalamus in TNP

• Regional GMV and thalamic NAA/Cr was negatively correlated to diary pain scores in TNP but not TMD

Moayedi et al. [39]

3D T1

CTA and VBM (ROI)

TMD (RDC/TMD)

17F; 33.1 ± 11.9 y

9.8 ± 8.25 (0.75–30) y

11

NPS¹, NEO-FFI [40]

17F; 32.2 ± 10.1 (20–50) y

• TMD patients had cortical thickening in S1 and PFC

• TMD clinical characteristics were related to brain structure:

- GMV in sensory thalamus positively correlated to TMD duration

- Cortical thickness in M1 and aMCC negatively correlated to pain intensity

- Pain unpleasantness negatively correlated to cortical thickness in OFC

- Positive correlation between neuroticism and OFC thickness

Moayedi et al. [41]

3D T1

CTA and VBM (ROI)

Ditto

Ditto

Ditto

Ditto

NPS¹

Ditto

• TMD had accelerated whole-brain GMV loss compared to HC, but TMD duration was not correlated to GMV

• Three types of aberrant relationships between GM and age in five focal brain regions:

- TMD had age-related GMV increases in thalamus whereas GM in HC was relatively sustained

- TMD had age-related cortical thinning in aMCC/pgACC, while HC had age-related cortical thickening

- TMD patients maintained cortical thickness in dorsal striatum and PMC with age, as opposed to age-related GMV decrease in HC.

• TMD duration was related to cortical thinning in PMC

Moayedi et al. [42]

DTI

FA, MD, and RD (ROI)

Ditto

Ditto

Ditto

Ditto

NPS¹

Ditto

In TMD:

• Decreased FA in right and left trigeminal nerves, and FA in right trigeminal nerve negatively correlated with TMD duration

• Widespread microstructure alterations of WM tracts related to sensory, motor, cognitive and pain functions, including a focal area of the corpus callosum

• Corpus callosum had higher connection probability to frontal pole and lower connection probability to dlPFC

• FA correlated with TMD clinical characteristics

- FA in tracts adjacent to vlPFC and tracts coursing through thalamus negatively correlated with pain intensity

- FA in internal capsule negatively correlated with pain intensity and unpleasantness

Salomons et al. [43]

3D T1 and DTI

CTA (ROI) and FA (TBSS)

Ditto

Ditto

Ditto

Ditto

NPS¹, Pain Catastrophizing Scale [44]

Ditto

In TMD:

• Magnitude of self-reported helplessness correlated with cortical thickness in SMA and MCC, regions implicated in cognitive aspects of motor behavior

• FA of connected white matter tracts along corticospinal tract was associated with helplessness and mediated the relationship between SMA cortical thickness and helplessness

Wilcox et al. [45]

3D T1 and DTI

VBM (ROI), FA and MD

TMD (RDC/TMD)

4M, 16F; mean ± SEM, 45.7 ± 2.9 (20–78) y

mean ± SEM: 9.15 ± 8.78 (1.5–30) y

14

VAS², MPQ [36]

5M, 21F; mean ± SEM, 52.3 ± 2.95 y

• Trigeminal neuralgia displayed 47% decrease in trigeminal nerve root volume but no change in DTI values

• TNP had 40% increase in nerve volume but no change in DTI values

• TMD had no change in volume or DTI values

Wilcox et al. [22]

3D T1 and DTI

VBM (ROI), FA and MD

TMD (RDC/TMD)

4M, 18F; mean ± SEM, 46.5 ± 2.6y

median: 9.7 y

15

VAS², MPQ [36]

7M, 33F; mean ± SEM, 48.3 ± 2.1 y

In TMD:

• Regional GMV decrease in medullary dorsal horn, in conjunction with an increase in MD

• Volumetric and MD changes in regions of the descending pain modulation system, including the PAG and nucleus raphe magnus

• Decreased FA in root entry zone of trigeminal nerve, spinal trigeminal tract and ventral trigemino-thalamic tracts