Laryngeal Dystonia, Dystonic Tremor and Vocal Tremor: Three Different Entities

Abstract

The main objective of this study was to compare the demographic and clinical characteristics of patients with laryngeal dystonia (LD), dystonic tremor (DT), and vocal tremor (VT). This was a retrospective longitudinal study. Data analysis from every patient diagnosed with LD, DT, or VT from January 1, 2010, to September 30, 2022, at a tertiary hospital center. Differential diagnosis between these entities was clinical (clinical history, voice assessment, and endoscopy) and confirmed by laryngeal electromyography. A total of 87 patients were included in this study: 50 patients with LD, 23 with DT, and 14 with VT. Age at diagnosis was significantly lower in patients with LD, with a mean age of 56.2years when compared to DT (67.6 years; P=0.002) and VT (70.5years; P=0.009). Furthermore, VT had a higher female prevalence (92.9%) when compared with LD (52%; P=0.011). LD was mainly adductor, with only two patients diagnosed with abductor LD, and DT was adductor in every case. Tremor direction in patients with VT was horizontal in 50% and mixed (horizontal+vertical) in 50%, while in DT was mixed in 65.2% and horizontal in 34.8%. LD was more commonly an isolated laryngeal movement disorder (78%) when compared to DT (47.8%; P=0.015) or VT (28.5%; P<0.001), which were more often secondary to generalized neurological disorders. There were no differences between groups on Voice Handicap Index-10, self-reported grade of dysphonia on a visual analogic scale (0-10), maximum phonation time, and G, R, B, A, and I in the GRBAS-I scale at diagnosis (P>0.05). S was significantly higher in LD when compared to VT (P<0.001) and nonsignificantly higher than in DT (P=0.075). LD, DT, and VT seem to be different entities with different demographics and clinical characteristics.