Applicability of Selective Electrical Surface Stimulation in Unilateral Vocal Fold Paralysis

Abstract

Objective Selective electrical surface stimulation (SES) of the larynx is not yet routinely considered therapy option in treatment of unilateral vocal fold paralysis (UVFP). Goal of this monocentric feasibility study was to provide systematic data on applicability of SES of intrinsic laryngeal muscles in UVFP under consideration of sensitivity and discomfort thresholds and nonselective side effects. Methods Thirty‐two UVFP patients were included in the study. Symmetric triangular‐shape, charge‐balanced pulse widths (PWs) of 1, 10, 25, 50, 100, 250, and 500 milliseconds (ms) were tested with increasing amplitudes (AMPs). The stimulation was delivered as a train of five pulses using square surface electrodes. Selective laryngeal responses were examined by flexible laryngoscopy. Nonselective side effects (swallowing reflex, coughing, different severity degrees of unspecific strap muscle/platysma response) were judged by observation. Results Selective laryngeal response could be triggered in 28/32 (87.5%) patients during respiration/rest and in 26/32 (81.3%) patients during phonation. The most effective PWs for the selective eliciting of selective bilateral vocal fold adduction are comprised between 50 and 100 ms in combination with an average AMP comprised between 7.1 and 7.2 mA. Conclusion Our results indicate that, in UVFP patients, PWs comprised between 50 and 100 ms in combination with a median AMP between 7.1 and 7.2 mA are expected to deliver in >75% of the cases a specific, effective, and safe bilateral adduction of the VF. Level of Evidence 3 Laryngoscope, 131:E2566–E2572, 2021

Selective Electrical Surface Stimulation to Support Functional Recovery in the Early Phase After Unilateral Acute Facial Nerve or Vocal Fold Paralysis

“…Hence, like seen for the facial nerve, correct electrical stimulation does not hinder the regeneration of the recurrent laryngeal nerve. These results consequently led Kurz et al to a prospective trial to systematically analyze optimal parameters for effective and tolerable stimulation of the vocal folds ( 64 ). Most effective were pulse durations between 50 and 100 ms with an average amplitude of 7.1 mA.…”