Abstract
Background: Idiopathic blepharospasm (BSP) is a common adult-onset focal dystonia. Neuroimaging technology can be used to visualize functional and microstructural changes of the whole brain.Method: We used resting-state functional MRI (rs-fMRI) and graph theoretical analysis to explore the functional connectome in patients with BSP. Altogether 20 patients with BSP and 20 age- and gender-matched healthy controls (HCs) were included in the study. Measures of network topology were calculated, such as small-world parameters (clustering coefficient [Cp], the shortest path length [Lp]), network efficiency parameters (global efficiency [Eglob], local efficiency [Eloc]), and the nodal parameter (nodal efficiency [Enod]). In addition, the least absolute shrinkage and selection operator (LASSO) regression was adopted to determine the most critical imaging features, and the classification model using critical imaging features was constructed.Results: Compared with HCs, the BSP group showed significantly decreased Eloc. Imaging features of nodal centrality (Enod) were entered into the LASSO method, and the classification model was constructed with nine imaging nodes. The area under the curve (AUC) was 0.995 (95% CI: 0.973–1.000), and the sensitivity and specificity were 95% and 100%, respectively. Specifically, four imaging nodes within the sensorimotor network (SMN), cerebellum, and default mode network (DMN) held the prominent information. Compared with HCs, the BSP group showed significantly increased Enod in the postcentral region within the SMN, decreased Enod in the precentral region within the SMN, increased Enod in the medial cerebellum, and increased Enod in the precuneus within the DMN.Conclusion: The network model in BSP showed reduced local connectivity. Baseline connectomic measures derived from rs-fMRI data may be capable of identifying patients with BSP, and regions from the SMN, cerebellum, and DMN may provide key insights into the underlying pathophysiology of BSP.
Highlights
Idiopathic blepharospasm (BSP) is one of the most common adult-onset focal dystonia that manifests with indirect or persistent excessive involuntary orbicularis oculi contraction and blinking [1, 2]
In our previous study, using the amplitude of low-frequency fluctuations (ALFF) to explore local cerebral activities, we found significantly decreased ALFF in the thalamus and increased ALFF in the orbitofrontal areas extending from the middle frontal gyrus (MFG) to the inferior frontal gyrus (IFG) in patients with BSP compared to healthy controls (HCs), suggesting abnormal sensorimotor integration and dysfunction of the thalamus in BSP [13]
For inter-group differences in global parameters without global signal regression (GSR), a decreased local connectivity was presented by significantly reduced clustering coefficient and local efficiency in patients with BSP (Cp: PBSP vs. HCs < 0.001; Eloc: PBSP vs. HCs = 0.005), while increased global connectivity was shown by significantly reduced path length and significantly increased global efficiency in patients with BSP [Lp: PBSP vs. HCs = 0.002; Eglob: PBSP vs. HCs = 0.003; Figure 2B]
Summary
Idiopathic blepharospasm (BSP) is one of the most common adult-onset focal dystonia that manifests with indirect or persistent excessive involuntary orbicularis oculi contraction and blinking [1, 2]. Patients with BSP have several non-motor symptoms, such as sensory symptoms (such as burning sensation and grittiness in the eyes) [4], psychiatric disorders (such as depression, anxiety, and obsessive-compulsive disorders) [5, 6], sleep disorders, and cognitive disturbances. Based on clear motor manifestations of patients, a diagnostic algorithm has been developed with 93% sensitivity and 90% specificity to distinguish BSP from other conditions of involuntary lid closure [7, 8]. Several treatment options can be administered by clinicians to effectively manage the symptoms of BSP, but usually only with short-term efficacy [9]. The pathophysiological mechanism of BSP needs to be better understood to develop new treatments. Idiopathic blepharospasm (BSP) is a common adult-onset focal dystonia. Neuroimaging technology can be used to visualize functional and microstructural changes of the whole brain
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