Botulinum toxin: dosing and dilution.

In the United States, the popularity of botulinum toxins as agents to treat muscle hypertonia has grown significantly over the last decade, despite lack of approval from the Food and Drug Administration for the indication of spasticity. Botox (botulinum toxin type A) and Myobloc (botulinum toxin type B) are Food and Drug Administration-approved for other indications, such as cervical dystonia. Another commercial preparation of type A, Dysport, has yet to reach the United States market as of this writing. Although botulinum toxin's efficacy in influencing spastic hypertonia is well accepted, the impact of certain clinical issues, such as dosing and dilution, on treatment outcome is not well established by published studies. This article will review important articles and selected abstracts on the use of botulinum toxin, specifically for spastic hypertonia in adults, with emphasis on current clinical practices as they relate to dosing and dilution.