Exploration of rich-club reorganization in facial synkinesis: insights from structural and functional brain network analysis.

Facial palsy therapies based on cortical plasticity are in development, but facial synkinesis progress is limited. Studying neural plasticity characteristics, especially network organization and its constitutive elements (nodes/edges), is the key to overcome the bottleneck. We studied 55 participants (33 facial synkinesis patients, 22 healthy controls) with clinical assessments, functional magnetic resonance imaging (fMRI), and diffusion tensor imaging (DTI). We analyzed rich-club organization and metrics of structural brain networks (rich-club coefficients, strength, degree, density, and efficiency). Functional brain network metrics, including functional connectivity and its coupling with the structural network, were also computed. Patients displayed reduced strength and density of rich-club nodes and edges, as well as decreased global efficiency. All nodes exhibited decreased nodal efficiency in patients. Patients had significantly increased functional connectivity and decreased structural-functional coupling strength in rich-club nodes, rich-club edges, and feeder edges. Our study indicates that facial synkinesis patients have weakened structural connections but enhanced functional transmission from rich-club nodes. The loss of connections and efficiency in structural network may trigger compensatory increases in functional connectivity of rich-club nodes. Two potential biomarkers, rich-club edge density and structural-functional coupling strength, may serve as indicators of disease outcome. These findings provide valuable insights into synkinesis mechanisms and offer potential targets for cortical intervention.

Tracking whole-brain connectivity dynamics in the resting-state fMRI with post-facial paralysis synkinesis.

BACKGROUND: Resting-state functional magnetic resonance imaging (rs-fMRI) is widely applied to explore abnormal functional connectivity (FC) in patients with post-facial paralysis synkinesis (PFPS). However, most studies considered steady spatial-temporal signal interactions between distinct brain regions during the period of scanning. OBJECTIVE: In this study, we aim to investigate abnormal dynamic functional connectivity (dFC) in PFPS patients. METHODS: We enrolled 31 PFPS patients and 19 healthy controls. All participants underwent rs-fMRI. Sliding windows approach was applied to construct dFC matrices. Next, these matrices were clustered into distinct states using the k-means clustering algorithm. RESULTS: We found that it was not the dFC patterns, but rather the temporal properties including the mean dwell time (MDT) and occurrence frequencies, that showed a significant difference between PFPS patients and healthy controls. Two randomly clustered dFC states were recognized for both groups. Among them, State 1 showed significantly lower connectivity compared to State 2 in patients group. Compared to healthy controls, the duration spent by the PFPS patients in the state with lower connectivity significantly increased and is positively correlated with the better facial function. CONCLUSIONS: In conclusion, aberrant dFC is a fundamental feature of brain dysfunction in PFPS patients, which is associated with the facial nerve function. These findings may contribute to a better understanding of the abnormal brain reorganization mechanisms in PFPS patients.

Spatial patterns of intrinsic brain activity and functional connectivity in facial synkinesis patients.

OBJECTIVES: As one of the most objectionable sequelae of facial paralysis, patients with facial synkinesis are more likely to be depressed and have lower quality of life than other facial paralysis patients. However, there is no research on the spatial patterns of intrinsic brain activity and functional connectivity in these patients. The objective of this study was to investigate the spatial patterns and cerebral plasticity of facial synkinesis patients. METHODS: A total of 20 facial synkinesis patients (18 men and 2 women; mean age: 33.35 ± 6.97 years old) and 19 healthy controls (17 men and 2 women; mean age: 33.21 ± 6.75 years old) were enrolled in this study. resting-state functional magnetic resonance imaging (rs-fMRI) data were collected, and the amplitude of low frequency fluctuation (ALFF), regional homogeneity (ReHo), and degree centrality (DC) were calculated for each participant. Two-sample t-tests were performed to compare the ALFF, ReHo, and DC maps between the two groups. RESULTS: Compared with the healthy controls, facial synkinesis patients exhibited decreased ALFF in the fusiform gyrus, lingual gyrus, parahippocampal gyrus, triangular inferior frontal gyrus, precentral gyrus, postcentral gyrus, cingulate gyrus, superior frontal gyrus, precuneus, caudate nucleus and thalamus; decreased ReHo in the cingulate gyrus, superior frontal gyrus, insula, superior temporal gyrus, orbital middle frontal gyrus, caudate nucleus and thalamus; and decreased DC in the frontal lobe, insula, cingulate gyrus, superior temporal gyrus, lenticular putamen, hippocampus and parahippocampal gyrus. We found significant overlap in the superior frontal gyrus across the ALFF, ReHo and DC analyses. CONCLUSIONS: In facial synkinesis patients, the neurological activity in brain areas is reduced and the local synchronization in motion-related brain regions is decreased. The superior frontal gyrus could be a crucial region in the unique spatial patterns of intrinsic brain activity and functional connectivity in these patients.

Electroneurography value as an indicator of high risk for the development of moderate-to-severe synkinesis after Bell's palsy and Ramsay Hunt syndrome.

Background: The degree of distress caused by the sequelae of peripheral facial nerve palsy usually depends on the severity of synkinesis. Objective: To clarify whether electroneurography (ENoG) can predict the severity of synkinesis after peripheral facial nerve palsy. Materials and methods: One-hundred and fourteen patients treated for facial nerve palsy at our hospital from April 2014-September 2016 were retrospectively reviewed. ENoG was performed 10-16 days after symptom onset. Patients were classified into Groups A (ENoG value 10%-20%, n = 9) and B (ENoG value <10%, n = 21). Eight months after symptom onset, electrophysiological and symptomatic outcomes were evaluated as the aberrant regeneration ratio of the blink reflex and the total synkinesis score of the Sunnybrook facial grading system, respectively. The outcomes of the groups were compared. Results: Group B had a significantly higher median aberrant regeneration ratio (0% versus 87%, p=.015), median total synkinesis score (1 versus 3, p < .001), and incidence of moderate-to-severe synkinesis (0% versus 57.2%, p=.003) than did Group A. Conclusions and significance: Patients with an ENoG value of <10% have higher risks of aberrant regeneration and moderate-to-severe synkinesis than those with an ENoG value of 10%-20%. Patients with ENoG values of <10% may require rehabilitation to prevent synkinesis.

Decreased Distance between Representation Sites of Distinct Facial Movements in Facial Synkinesis-A Task fMRI Study.

This study aimed to investigate the cortical functional alterations in patients with unilateral facial synkinesis using the task-designed functional magnetic resonance imaging. Fourteen unilateral synkinesis followed by peripheral facial nerve palsy patients and eighteen healthy adults were recruited in this study. Four facial motor tasks, i.e. left/right blinking and left/right smiling, were performed by each subject during the scans. Based on the activation maps, the spatial distance between the representation sites in the contralateral pre-/post-central gyrus of left or right blinking and smiling tasks (i.e. left/right B-S-distance) were calculated. Patients with unilateral facial synkinesis showed decreased B-S-distances during blinking and smiling tasks on the affected half face (9.68 ±â€¯3.92 mm) compared to both average distances in healthy controls (14.95 ±â€¯5.55 mm; p = 0.002) and unaffected half face tasks in patients (16.19 ±â€¯7.87 mm; p = 0.011). These findings demonstrated cortical reorganization in facial synkinesis and suggested a conceivable mechanism corresponding to the simultaneous facial movement. This potentially provides a new modulation target for preventive, therapeutic and rehabilitative maneuver of this disease.