Background: Botulinum toxin type A (BoNT/A) is 20-50 times more effective than Botulinum toxin type B (BoNT/B) concerning the treatment of muscular hypercontractions [Sloop, R.R., Cole, B.A., Escutin, R.O., 1997. Human response to botulinum toxin injection: type B compared with type A. Neurology 49, 189-194]. Botulinum toxins block motor nerves as well as autonomic fibres [Rand, M.J., Whaler, B.C., 1965. Impairment of sympathetic transmission by botulinum toxin. Nature 206, 588-591].
Objective: Purpose of this study was to analyse the dose dependent reduction of sweating using the BoNT/A preparation Botox and to compare the results with our earlier results analysing Dysport [Braune, C., Erbguth, F., Birklein, F., 2001. Dose thresholds and duration of the local anhidrotic effect of botulinum toxin injections: measured by sudometry. Br. J. Dermatol. 144, 111-117] and Neurobloc (BoNT/B) [Birklein, F., Eisenbarth, G., Erbguth, F., Winterholler, M., 2003. Botulinum toxin type B blocks sudomotor function effectively: a 6 month follow up. J. Invest. Dermatol. 121, 1312-1316].
Methods: Different doses of Botox were injected subcutaneously (n=27 healthy subjects). Planimetrical analyses of the area of anhidrosis and quantitative sudomotor-axon-reflex testing (QSART) were done after 3 weeks, 3 and 6 months.
Results: A threshold dose of 1.25 MU Botox led to anhidrotic skin spots after 3 weeks. The duration of anhidrosis was prolonged for 3 months when 17.5 MU and for 6 months when 50 MU were injected. Anhidrotic area size decreased with time (p=0.001), indicating partial recovery at the edges. After 3 weeks, QSART had significantly decreased to 29% of baseline. With doses of 70 MU or more it decreased to zero. After 3 months, QSART had returned to 68% of baseline and after 6 months to 87%.
Conclusions: Botox dose-dependently suppressed sweating. Comparison to Dysport and Neurobloc revealed a strikingly similar efficacy after 3 weeks and 3 months for all preparations. BoNT/A in general induced a more sustained anhidrosis than BoNT/B.