Neuroplastic Perspective on Facial Symmetry Recovery: Insights from Rich-Club Dynamics

Unilateral facial paralysis is a condition marked by facial asymmetry. Although reconstructive operations, such as masseteric-to-facial nerve transfer combined with static suspension, significantly improve facial symmetry, patient outcomes can vary considerably. This study aimed to explore cerebral reorganization, focusing on rich-club (RC) organization and structural connectivity (SC)-functional connectivity (FC) coupling as potential biomarkers for facial symmetry recovery.

The authors enrolled 40 patients with severe oral commissure drooping caused by unilateral facial nerve lesions, who underwent masseteric-to-facial nerve transfer combined with static suspension. Using functional magnetic resonance imaging and diffusion tensor imaging, the authors analyzed RC properties, the macroscale SC, and FC. Based on postoperative symmetry levels, patients were categorized into symmetry and asymmetry groups for comparison.

Patients with better facial symmetry demonstrated stronger SC-FC coupling. In addition, greater strength in non-RC nodes, along with stronger feeder and local edges, played a compensatory role in improving facial symmetry. In contrast, patients with facial asymmetry exhibited increasing FC in RC and non-RC nodes, possibly as a maladaptive compensatory mechanism.

The authors' study highlights RC organization and SC-FC coupling as potential biomarkers for assessing and monitoring facial symmetry recovery in facial paralysis patients after surgery. These findings offer valuable insights into the brain's adaptive responses, serving as sensitive indicators of disease symptoms and functional performance.