Laryngeal botulinum toxin injections for disabling stuttering in adults

Stuttering is an action-induced speech disorder with involuntary, audible, or silent repetitions or prolongations in the utterance of short speech elements (sounds, syllables) and words. Symptomatic treatment programs frequently have initial success; persistent benefit is variable and many patients remain disabled. Stuttering has many characteristics similar to spasmodic dysphonia (laryngeal dystonia), often including the presence of adductor laryngeal spasms that obstruct airflow (glottal block). We hypothesized that relief of the spasmodic dysphonic glottal blocks in stutterers would modify the stuttering phenomenon and increase fluency. We therefore studied the effects of bilateral vocal fold injections of botulinum toxin type A (BTX) on dysfluency and speech characteristics in stuttering. We treated 14 adult patients (12 men, 2 women) with persistent stuttering and glottal block who previously failed standard speech therapy with 1.25 U BTX into each thyroarytenoid (vocalis) muscle. Fluency evaluations included the Stuttering Severity Instrument, the Perceptions of Stuttering Inventory, and a global rating scale (percent of normal function). Patients were evaluated at baseline and at 2-, 6-, and 12-week follow-up visits. Improvement in fluency documented by each rating instrument occurred at 2 and 6 weeks, with functional relapse by 12 weeks in most patients. We conclude that therapeutic laryngeal injections of botulinum toxin are useful in the management of stuttering with glottal block and result in a moderate improvement in fluency. When an adult patient with developmental stuttering with glottal blocks has failed speech interventional therapy and presents for treatment, a trial of BTX can be considered early. The results of BTX treatment will be known within a relatively short period of time (weeks), whereas the impact of pharmacological trials can take several months or years. Although BTX therapy does not result in normal fluency, BTX treatment is a safe, reasonable intervention to use either in isolation or in conjunction with more classic therapies or pharmacotherapy. Further study is required to evaluate long-term efficacy.