Longitudinal Follow‐Up of Adductor Spasmodic Dysphonia Patients After Botulinum Toxin Injection: Quality of Life Results

Abstract

Botulinum toxin injections are used routinely to treat patients with adductor spasmodic dysphonia. After an initial "breathy phase," most patients experience improvement for a few weeks to months and then a gradual decline until their next injection. In this study, voice-related quality of life (VRQOL) data were collected at 4 week intervals through one to three injection cycles in an attempt to quantify the proportion of each cycle during which patients experience meaningful benefit. Prospective, nonrandomized case series. Patients receiving stable-dose botulinum injections for adductor spasmodic dysphonia were invited to participate. Voice recordings and clinical outcomes data were collected by telephone every 4 weeks throughout each injection cycle. Quality of life data were normalized for cycle length and interpolated to generate composite curves. Twenty-two patients completed data collection for at least one full injection cycle. The average cycle was 25.9 weeks; the mean age was 59.8 years. On a 100-point scale, the total VRQOL scores peaked at 77.4, at 30% of the cycle, then gradually declined. The social-emotional (SE) subscale scores were significantly better than the physical subscale scores (P < .05). The total VRQOL score exceeded 75 during only 14% of the cycle (52.6% for SE subscores, 0% for physical subscores). If the threshold is lowered to 70, the total VRQOL exceeded this level during 54.6% of the cycle (69.6% for SE subscores, 44.1% for physical subscores). For the 11 patients completing three full injection cycles, there were no significant differences between the three cycles, and the mean VRQOL scores were similar to the values given above. At the beginning and end of each cycle, the total VRQOL scores averaged 52.8 (56.0 for SE subscale, 50.7 for physical subscale). Although botulinum toxin injections provide significant improvement for these patients, the initial breathy phase and the late declining phase add up to a significant proportion of each cycle spent with a reduced quality of life. At best, the total VRQOL averaged below 80%. This longitudinal study provides a unique look at the effect of this condition and its treatment on these patients' lives. A suitable long-term treatment for this condition is needed to eliminate the cyclical voice results experienced with the botulinum toxin injection approach.