To our knowledge, the ALFF method has not previously been used to study the potential relationship between brain activity changes and clinical manifestations in patients with OF. This study aimed to explore the cerebral neural changes after orbital fracture uing the fALFF technique (Fig. 5). The study found significantly lower fALFF values in the LACG and the RSTG in OF patients (Fig. 6). In previous studies, the fALFF method has been applied to a series of ophthalmological diseases, including normal-tension glaucoma[20], monocular blindness[21], retinal vein occlusion[22], diabetic retinopathy and nephropathy[23] (Table 3), demonstrating its potential for clinical application.
The anterior cingulate gyrus (ACG) is a functional area associated with many physiological functions, is located in the medial brain and passes longitudinally through the parietal lobe, and its main roles are in memory[
24], action– outcome learning[
25–
27], emotion and reward-related processing[
28]. The research of Hornak et al.[
29] showed that in some cases, the ACG plays an important part in voice and facial expression recognition, while Lane et al.[
30–
32] studied anterior cingulate injury in subjective emotional experience, and found that ventral ACG and Brodmann’s area 9 may be activated during mood fluctuations. Based on the functions of the anterior cingulate gyrus, some researchers have explored its diagnostic value in Parkinson's disease[
33], depression[
34] and acute and chronic pain[
35]. In addition, a previous study found that the prefrontal cingulate gyrus can respond to visual stimuli[
36]. In the present study, given the reduced visual responses in patients with OF, the results may indicate a compensatory mechanism for vision loss in patients with OF.
The superior temporal gyrus (STG) is a functional area of the brain located in the temporal lobe, closely related to emotional and speech processing[37, 38]. The STG is a component of the default mode network, which is inhibited during brain activity and excited during rest. Liu et al.[39] used the rsMRI-fALFF method to study the STG in depression. They found that lower the fALFF values of STG correlatedgreater reductions on the Hamilton rating scale for depression, and inferred that STG neural changes were closely related to the effect of early treatment for depression. In addition, Wang et al.[40] measured functional connectivity density in STG and found that abnormal connectivity is negatively correlated with the treatment effect. In the present experiment, the fALFF value of the right STG in OF patients was significantly lower than that in healthy controls, and we speculate that this decrease may be a compensatory mechanism for the recovery of brain function in patients with OF. The results suggest that the fALFF value may be used as a reliable index to gauge therapeutic effects of clinical treatment. Moreover, it was discovered that in the patients with OF, fALFF values in the RSTG were negatively correlated with anxiety and depression scores, which may indicate a self-regulation mechanism in this brain area, with brain function being temporarily inhibited.(Table 4)
Table 3
ALFF method applied in ophthalmological diseases
Author
|
Year
|
Disease
|
Brain areas
|
Increased fALFF values
|
Decreased fALFF values
|
Li HL, et al.(20)
|
2020
|
normal-tension glaucoma
|
_
|
RAG, RACL
|
Fang JW, et al.(21)
|
2020
|
monocular blindness
|
LP, RPI, LPI
|
LCA
|
Tong Y, et al. (22)
|
2020
|
retinal vein occlusion
|
LC, RC, RB, LI
|
RC, RT
|
Wang R, et al.(23)
|
2021
|
primary angle-closure glaucoma
|
BSFG
|
LC, LMTG
RMTG, RPG
|
Abbreviations: fALFF, fractional amplitude of low-frequency fluctuation; RAG, right angular gyrus; LP, left precuneus; LMTG, left middle temporal gyrus; LCA, left anterior cingulate; RPI, right inferior parietal lobe; LPI, left inferior parietal lobe; RMTG, right middle temporal gyrus; LC, left cerebellum; RC, right cerebellum; RB, right brainstem; RC, right calcarinesulcus; BSFG, bilateral superior frontal gyrus; LIG, left lingual gyrus; RPG, right precentral gyrus; RT, right thalamus; LI, left insula; RACL, right anterior cuneiform lobe. |
Table 4
Brain areas of altered fALFF values and its potential effects.
Brain regions
|
Experimental result
|
Brain function
|
Anticipated results
|
Cingulum_Ant_L
|
OF<HCs
|
Memory, action–outcome learning, emotion and reward-related processing
|
Behavioral disorders, memory impairment, depression,
|
Temporal_Sup_R
|
OF<HCs
|
Emotional and speech processing, curative effect index
|
Mental disorders, speech disorder, reflecting treatment effect
|
Abbreviations: Cingulum_Ant_L, left anterior cingulate cortex; Temporal_Sup_R, right superior temporal gyrus; OF, orbital fractures; HCs, healthy controls. |
This study has some limitations, one of which is the relatively small sample size and the other is that the sample source was limited and not completely matched. Therefore, future research should use larger and more closely matched samples to further clarify the neural changes in patients with orbital fractures, and to provide a more intuitive clinical efficacy index for treatment. In conclusion, this study has demonstrated that patients with OF have reduced fALFF values in specific cerebrum areas, indicating changes in spontaneous brain activity. Further research on the mechanism underpinning brain activity changes in patients with OF may be helpful to advance understanding of this condition.