Comprehensive description of clinical features of laryngeal dystonia and dystonic vocal tremor.

Abstract

Objective: This study aimed to characterise laryngeal dystonia (LD) phenotypes using combined classification criteria and to evaluate treatment outcomes with botulinum neurotoxin type A (BoNT-A).

Methods: The study retrospectively reviewed patient medical records from our clinic over 5 years to identify cases of LD. We classified LD subtypes (adductor, abductor, mixed) and dystonic vocal tremor (DVT) based on updated criteria.

Results: We analysed 75 cases, predominantly adductor LD (60%) and DVT (28%). In all, 84% of patients were females, diagnosed around 68 years of age. The DVT group had late-onset dysphonia that worsened over time and was associated with essential tremor in almost half of cases. Subjects with mixed LD had the greatest increase in Voice Handicap Index (VHI) over time and the longest duration of disease in all cases associated with DVT. Abductor LD cases had the most severe dysphonia (VHI: 73.3). Two-thirds of cases received BoNT-A therapy; most had adductor LD and had received treatment for longer times and had the lowest rate of treatment refusal.

Conclusions: Correct LD classification aids in diagnosis, prognosis and treatment; it should be dynamic and evolve with the patient's history. However, there is a lack of data in the literature on certain aspects of LD, emphasising the need for further research to improve clinical practice.