Laryngeal Sensitivity in Patients with Laryngeal Adduction Dystonia Before and After Botulinum Toxin Injection

This study aims to investigate laryngeal sensitivity and vocal handicap in individuals with adduction laryngeal dystonia (AdLD), preapplication and postapplication of botulinum toxin (BT), through self-assessment protocols.

Twenty-five individuals diagnosed with AdLD (AdLD Group), treated through BT application, aged 34 and 83 years, and 17 vocally healthy individuals, control group (CG), participated in the study. The groups were matched for sex and age. The voice of the AdLD participants was recorded for auditory-perceptual judgment before BT application. The voice of the CG was recorded on the same day they responded to the two self-assessment protocols. The speech tasks were the sustained vowel "é" and CAPE-V sentences. The AdLD group responded to the Laryngeal Hypersensitivity Questionnaire (LHQ-Newcastle) and the Vocal Handicap Index-10 (VHI-10) at two time points: before the application of BT and 30 days after. The CG responded to the same protocols only once.

When evaluating the results of the AdLD group before and after the application of BT, there was a statistically significant difference in the comparison of the scores of both questionnaires applied. The comparison between the value of the general degree of vocal deviation (G) as mild, moderate or intense, and the values of the questionnaires (VHI-10 and LHQ) for the two groups before the application of BT showed a statistical difference only in AdLD, which evidenced a greater association between the scores in the questionnaires and changes in G, being moderate and intense.

It is possible to recognize the consistent relationship between laryngeal sensory symptoms and AdLD, as well as the negative impact on voice quality and quality of life reported by individuals affected by this condition, when compared to vocally healthy individuals. Treatment with BT has proven to be effective in improving symptoms of laryngeal hypersensitivity and voice-related quality of life.