Effect of Combined Respiratory Muscle Training (cRMT) on Dysphonia following Single CVA: A Retrospective Pilot Study

Although dysphonia is less prevalent than dysphagia following cerebrovascular accidents, dysphonia does contribute to the burden of disease resulting from stroke. Strengthening muscles of the larynx and respiratory tract through respiratory muscle training (RMT) has proven effective in improving voice after neurological insult. However, approaches to strengthen only the expiratory muscle groups (EMST) dominate the clinical study literature, with variable outcomes. By focusing on exhalation, the contribution of inspiratory muscles to phonation may have been overlooked. This study investigated the effect of combined respiratory muscle training (cRMT) to improve voice function in stroke patients.

Recorded data of twenty patients with dysphonia following stroke were allocated to an intervention (IG) or a control group (CG) based upon whether they chose cRMT or not while awaiting pro bono voice therapy services. The intervention group (n = 10) was treated daily with three 5-minute sessions of combined resistive respiratory muscle training for 28 days, while the control group (n = 10) received no cRMT or other exercise intervention. Perceptual and acoustic measurements as well as a pulmonary function test were assessed pre-and post-intervention.

The intervention group demonstrated significant improvements after 28 days of cRMT in peak flow (127%), patient self-perception of voice improvement (84.41%), as well as in all categories of the Consensus Auditory-Perceptual Evaluation of Voice (CAPE-V): overall severity (63.22%), roughness (54.76%), breathiness (61.06%), strain (63.43%), pitch range (48.11%) and loudness (57.51%), compared to the control group who did not receive treatment. Furthermore, cRMT also led to significant improvements in maximum phonation time (212.5%), acoustic parameters of vocal intensity, and total semitone range (165.45%).

This pilot study shows promise of the feasibility and effectiveness of cRMT to lessen the signs and symptoms of dysphonia while simultaneously improving breath support.