Altered intrinsic brain activity in patients with toothaches using the amplitude of low-frequency fluctuations: a resting-state fMRI study

Figures & data

Table 1 Demographics and pain characteristics in TA patients

	Sex	Age (years)	Duration	Sides	Handedness	Pain characteristics	VAS
1	Male	54	0.33	L	R	Sharp pain	7
2	Female	36	0.25	L	R	Sharp pain	8
3	Female	50	0.25	L	R	Dull pain	6
4	Female	45	0.33	L	R	Dull pain	4
5	Male	41	0.17	L	R	Dull pain	6
6	Female	56	0.17	L	R	Dull pain	5
7	Female	59	0.17	L	R	Sharp pain	9
8	Female	28	0.04	L	R	Sharp pain	11
9	Male	31	0.13	L	R	Dull pain	5
10	Female	36	0.08	L	R	Sharp pain	8
11	Female	39	0.17	L	R	Sharp pain	7
12	Female	26	0.04	L	R	Sharp pain	9
13	Male	31	0.13	R	R	Sharp pain	9
14	Female	59	0.19	R	R	Dull pain	4
15	Male	48	0.27	R	R	Dull pain	4
16	Male	18	0.16	R	R	Dull pain	5
17	Male	42	0.04	R	R	Dull pain	4
18	Male	44	0.17	R	R	Dull pain	4

Abbreviations: HC, healthy control; R, right; TA, toothache; VAS, visual analog scale.

Table 2 Demographics and behavioral results of TA and HC groups

	TA	HC	t-value	P-value
Male/female	8/10	8/10	N/A	>0.99
Age (years)	41.28±11.48	40.73±12.48	0.088	0.679
Handedness	18 R	18 R	N/A	>0.99
Duration (years)	0.17±0.09	N/A	N/A	N/A
VAS	6.37±2.13	N/A	N/A	N/A

Notes: Independent t-tests comparing the two groups (P<0.05 represented statistically significant differences). Data shown as mean SD or n.

Abbreviations: HC, healthy control; N/A, not applicable; R, right; TA, toothache; VAS, visual analog scale.

Table 3 Brain regions with significant differences in ALFF between TA patients and HCs

L/R	Brain regions	BA	MNI coordinates			Peak voxels	t-value
			X	Y	Z
L	Fusiform gyrus	18	−24	−81	−9	59	6.2598
R	Inferior occipital gyrus	18, 19	48	−75	−6	23	6.6522
R	Lingual gyrus	18	21	−84	−9	25	5.2737
R	Superior occipital gyrus	18, 19, 31	18	−84	18	178	7.7558
L	Postcentral gyrus	3, 40	−39	−36	51	66	6.9278
R	Paracentral lobule	3, 4	9	−36	63	28	6.3765

Note: The statistical threshold was set at voxel with P<0.01 for multiple comparisons using false discovery rate.

Abbreviations: ALFF, amplitude of low-frequency fluctuation; B, bilateral; BA, Brodmann area; HC, healthy control; L, left; MNI, Montreal Neurological Institute; R, right; TA, toothache.

Figure 1 Spontaneous brain activity in patients with toothache and HCs.

Notes: There were significant differences in brain activity (A, B). The red regions indicate higher ALFF values. AlphaSim corrected at a cluster size >40 voxels and a level of P<0.05 for multiple comparisons, obtained via Gaussian random field theory. (C) The mean values of ALFF between the TA group and HCs.
Abbreviations: ALFF, amplitude of low-frequency fluctuation; TA, toothache; HC, healthy control; LFG, left fusiform gyrus; LPG, left postcentral gyrus; RIOG, right inferior occipital gyrus; RSOG, right superior occipital gyrus; RLG, right lingual gyrus; RPL, right paracentral lobule.

Figure 2 ROC curve analysis of the mean ALFF values for altered brain regions.

Notes: (A) The area under the ROC curve was 0.992, (P<0.001; 95% CI: 0.965–1.000) for RIOG, RLG 1.000 (P<0.001; 95% CI: 1.000–1.000), LPG 0.950 (P<0.001; 95% CI: 0.851–1.000). (B) The area under the ROC curve was 0.967 (P<0.001; 95% CI: 0.896–1.000) for LFG, RSOG 0.992 (P<0.001; 95% CI: 0.965–1.000), RPL 0.983 (P<0.001; 95% CI: 0.941–1.000).
Abbreviations: ALFF, amplitude of low-frequency fluctuation; AUC, area under the curve; ROC, receiver operating characteristic; LFG, left fusiform gyrus; LPG, left postcentral gyrus; RIOG, right inferior occipital gyrus; RSOG, right superior occipital gyrus; RLG, right lingual gyrus; RPL, right paracentral lobule.

Figure 3 The ALFF results of brain activity in the TA group. (A) The VAS of the left eye positively correlated with ALFF signal values of the right paracentral lobule (r=0.639, P=0.025). (B) There is no correlation between the VAS and the right paracentral lobule.

Note: The sizes of the spots denote the degree of quantitative changes.
Abbreviations: ALFF, amplitude of low-frequency fluctuation; TA, toothache; HC, healthy control; VAS, visual analog scale; BA, Brodman area.

Figure 4 Correlations between mean ALFF signal values and behavioral performance.

Notes: Compared with the HCs, the ALFF of the following regions were increased to various extents: 1) left postcentral gyrus (Ba 3, 40, t=6.9278), 2) right paracentral lobule (Ba 3, 4, t=6.3765), 3) right superior occipital gyrus (Ba 18, 19, 31, t=7.7558), 4) right lingual gyrus (Ba 18, t=5.2737), 5) right inferior occipital gyrus (Ba 18, 19, t=6.6522), and 6) left fusiform gyrus (Ba 18, t=6.2598) in TA patients.
Abbreviations: ALFF, amplitude of low-frequency fluctuation; VAS, visual analog scale.

Table 4 ALFF method applied in pain-related diseases

Authors	Year	Diseases
Xue et al^Citation42	2013	Migraine
Wang et al^Citation43	2017	Classic trigeminal neuralgia
Pan et al^Citation44	2018	Acute eye pain
Zhang et al^Citation12	2017	Low back pain
Ma et al^Citation45	2015	Visceral pain
Liu et al^Citation46	2017	Dysmenorrhea

Abbreviation: ALFF, amplitude of low-frequency fluctuation.

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