Repeated treatments of drooling with botulinum toxin B in neurology.

Objectives: To investigate efficacy, saliva flow, and composition in repeated BoNT-B treatments of drooling.

Materials And Methods: Seventeen neurological patients (median 66 years), referred for treatment of drooling participated in this observational study. Median total doses of 4000 units botulinum toxin type B (BoNT-B, Neurobloc(®)) were injected with at least 3 months intervals into parotid and submandibular glands using ultrasound guidance. Measures of drooling and saliva collection for analysis were obtained before treatment, and 6, 12, and eventually 18 weeks after.

Results: Number of treatment series in each patient was 1-7. Compared to baseline, saliva flow rate and drooling were reduced 30-70% 6 weeks after treatment in the first series, while sodium, chloride, and total protein increased 20-80% (t-tests; P < 0.05). After 12 weeks, drooling was still significantly reduced, saliva flow tended to be, and saliva composition was back to baseline. Frequent side effects were viscous saliva and dry mouth. Due to fading effect in eight patients, individual decisions were taken to change from BoNT-B to BoNT-A. Similarly, the outcome was significantly reduced over time in six patients completing five subsequent BoNT-B treatment series (ANOVA; P < 0.05).

Conclusion: In the first series, BoNT-B treatment resulted in marked reduction of drooling and saliva flow rate with some relapse after 12 weeks. The viscous saliva was ascribed to increased total protein content and compensatory mechanisms related to ß-adrenergic receptor-specific actions. With patients needing long-term treatment, it should be noted that the efficacy of repeated BoNT-B may fade with time.