Targeted transtracheal stimulation for vocal fold closure.

Area of Science:

• Neurology
• Otolaryngology
• Biomedical Engineering

Background:

• Neurological disorders and stroke can cause head and neck paralysis, leading to dysphagia (difficulty swallowing).
• Dysphagia significantly increases the risk of aspiration pneumonia and mortality.
• The recurrent laryngeal nerve (RLN) controls vocal fold function, crucial for airway protection.

Purpose of the Study:

• To test the hypothesis that transtracheal functional electrical stimulation (FES) can induce controlled vocal fold adduction.
• To evaluate the efficacy of FES applied via electrodes placed within the trachea.
• To explore a minimally invasive method for stimulating the RLN.

Main Methods:

• Bipolar electrodes were positioned at 15° intervals on the canine tracheal mucosal surface.
• Electromyography (EMG) recorded laryngeal muscle activity, and laryngoscopy visualized vocal fold movement.
• Current was applied to assess stimulation thresholds and vocal fold response.

Main Results:

• Optimal EMG thresholds for stimulation were identified at specific locations within the trachea.
• A rotatable electrode pair successfully stimulated both RLNs bilaterally in all subjects.
• Transtracheal FES achieved complete glottal closure in 6 of 8 subjects, sustained during laryngeal elevation.

Conclusions:

• Transtracheal electrode placement is an effective method for minimally invasive FES application.
• This technique successfully induced vocal fold adduction, demonstrating potential for airway protection.
• Provides a novel approach for studying laryngeal function and developing therapeutic interventions for dysphagia.