Botulinum Toxin A and B in sialorrhea: Long-term data and literature overview

In recent years, Botulinum Toxin has been shown to be efficacious and safe in the treatment of sialorrhea, but scanty data are available on its long term use. The aim of this study was to investigate adverse events, discriminate differences in safety, and evaluate the efficacy of long-term use of both abobotulinumtoxinA and rimabotulinumtoxinB ultrasound-guided injections for sialorrhea in a retrospective trial. Moreover we review the literature on this topic.

Consecutive patients with severe sialorrhea and receiving at least two ultrasound-guided intrasalivary glands abobotulinumtoxinA 250 U or rimabotulinumtoxinB 2500 U injections were included. Clinical and demographic data were collected. Safety and tolerability were assessed on the basis of patients' self-reports. Efficacy was assessed by recording the duration of benefit and by the Drooling Severity Scale and Drooling Frequency Scale 4 weeks after intervention. A review of literature was performed using 'Botulinum Toxin' and/or 'drooling' and/or 'sialorrhea' and/or 'hypersalivation' as keywords.

Sixty-five patients (32 Amyotrophic Lateral Sclerosis and 33 Parkinson's Disease) were treated in a total of 317 sessions (181 rimabotulinumtoxinB and 136 abobotulinumtoxinA). Both serotypes induced a clear-cut benefit in 89% of injections. Mean benefit duration was 87 days (range 30-240), similar for abobotulinumtoxinA and rimabotulinumtoxinB but significantly shorter in Amyotrophic Lateral Sclerosis group compared to Parkinson's Disease (p < 0.001). Older age was positively correlated to benefit duration (p = 0.003). Botulinum Toxin-related and injection-related side effects complicated respectively 8,2% and 1,5% of treatments. The only Botulinum Toxin-related adverse event was a change of saliva thickness, mostly rated mild to moderate and more frequent in Amyotrophic Lateral Sclerosis patients (p = NS).

Both 250 U abobotulinumtoxinA and 2500 U rimabotulinumtoxinB administered by ultrasound-guided intrasalivary gland injection are safe and effective in treating sialorrhea, even in long-term follow-up. Older age is significantly associated with longer benefit duration. Parkinson's Disease patients showed a more favorable safety-efficacy ratio than did Amyotrophic Lateral Sclerosis patients, due to lower adverse events (p = NS) and longer benefit duration (p < 0.001).