Exploring Facial Nucleus-Centered Connectivity in Hemifacial Spasm: Novel Insights into Pathogenesis and Surgical Impact

Hemifacial spasm (HFS) is a chronic neurological disorder characterized by involuntary muscle contractions of the face, significantly impacting patients' quality of life. Although the facial nerve nucleus has been implicated in HFS pathogenesis, specific research on its functional connectivity within whole-brain networks remains limited. This study aimed to investigate alterations in whole-brain functional connectivity with the facial nerve nucleus as the region of interest (ROI) in HFS patients, before and after microvascular decompression (MVD), to uncover potential mechanisms underlying the disorder and the impact of surgical intervention. Resting-state functional magnetic resonance imaging (rs-fMRI) was conducted on 30 HFS patients and 30 matched healthy controls. Functional connectivity (FC) was analyzed using the facial nerve nucleus as the seed ROI. Demographic, clinical, and laboratory data were collected, including spasm severity, anxiety and depression scores, and preoperative biomarkers. Statistical analyses assessed differences in FC and its correlation with clinical parameters. HFS patients demonstrated significantly increased FC between the left facial nucleus and the right parahippocampal gyrus, as well as between the right facial nucleus and the right fusiform gyrus, compared to healthy controls. These patterns persisted postoperatively, with additional increased FC observed between the right facial nucleus and bilateral superior temporal gyri. Correlation analyses revealed that left facial nucleus-right parahippocampal gyrus FC was positively associated with spasm severity and fibrinogen levels, while right facial nucleus-right fusiform gyrus FC was negatively correlated with monoamine oxidase (MAO) levels. ReHo of both facial nucleus showed significant differences between preoperative HFS patients and healthy controls, whereas ALFF/fALFF and lateralisation of facial nucleus did not show significant between-group differences. This study highlights the role of altered FC between the facial nucleus and brain regions involved in memory, emotion, and visual processing in HFS pathogenesis. While MVD provides symptomatic relief, its short-term effects on FC appear limited, suggesting that functional connectivity changes are chronic and may serve as biomarkers for disease monitoring. These findings provide novel insights into the neural mechanisms of HFS and emphasize the need for further research on long-term brain network adaptations post-surgery.