Neuromodulation and vocal changes induced by early interventions in unilateral vocal fold paralysis
(2025)
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- Abstract
- This thesis investigates whether early intervention could facilitate the reinnervation of the recurrent laryngeal nerve, enhance the recovery of mobility in the paralyzed vocal fold, and/or improve vocal recovery in cases of unilateral vocal fold paralysis (UVFP). The research was structured in two main stages. The first consisted of three key lines of inquiry: a review of behavioral voice therapy studies for UVFP, an examination of methodological strategies to improve experimental validity, particularly through the development of sham intervention protocols, and a synthesis of neuroimaging literature identifying brain regions consistently activated during sustained vowel phonation tasks using functional magnetic resonance imaging (fMRI). These preliminary investigations laid the groundwork for the second stage, helping to define the conceptual and methodological framework for the longitudinal study and to guide the analysis and interpretation of collected data. The second stage consisted of a prospective longitudinal multiple-case study involving three UVFP patients with differing recovery trajectories: one with spontaneous nerve recovery, one with nerve recovery following injection laryngoplasty with resorbable injectable, and one with no recovery despite behavioral voice therapy. All patients received early interventions, including both active and sham procedures. Each underwent a comprehensive evaluation protocol, including anatomical, task-based, resting-state, diffusion MRI, at four time points over a nine-month period. A control participant was also included. Three key findings emerged from this longitudinal investigation. First, shortly after the onset of UVFP, task-based fMRI revealed phonation-related hyperactivation, coinciding with increased resting-state connectivity among phonatory brain regions. Second, in the patient who underwent injection laryngoplasty, bilateral activation of brainstem nuclei involved in motor and sensory control of the vocal folds was observed during phonation. In this same patient, resting-state connectivity not only between the bilateral brainstem nuclei but also between the brainstem nuclei of the mobile side and other cortical and subcortical regions, was found to correlate with an aerodynamic measure of voice function. Third, following the injection, bilateral improvements in the structural integrity of the lower corticobulbar tracts were observed. Collectively, these findings suggest that restoring somatosensory feedback during phonation, through interventions such as injection laryngoplasty, may support the neural recovery process. The data also point to compensatory neural activity emerging from neural structures on the unaffected side. These findings highlight a broader pattern of central plasticity in response to peripheral intervention, involving not only the brainstem nuclei but also broader functional and structural networks, including the corticobulbar pathways connecting the cortex to the brainstem nuclei controlling vocal function. Although exploratory and limited by the small sample size, particularly the reliance on a single neuroimaging case, the thesis contributes meaningfully to an underexplored domain in UVFP research. It raises important methodological and theoretical questions and offers a foundation for future studies aimed at optimizing early interventions and deepening our understanding of neuroplasticity in vocal recovery.
- Affiliations
UCLouvain SSH/IPSY - Psychological Sciences Research Institute UCLouvain SSS/IONS - Institute of NeuroScience
Citations
Dedry, M. (2025). Neuromodulation and vocal changes induced by early interventions in unilateral vocal fold paralysis. https://hdl.handle.net/2078.5/248877