Botulinum toxin is an effective therapy for control of many involuntary movement disorders involving abnormal muscle contractions. The FDA has approved Botox for the treatment of blepharospasm, cervical dystonia, chronic migraine, and upper limb spasticity. Injections may also be used off-label in conditions such as excessive drooling, sweating, other forms of dystonia, or hemifacial spasm.
There are different types of botulinum toxin available in the United States with different names (Botox, Dysport, Myobloc, Xeomin). However, the mechanism by which the toxin works is the same for all formulations. Botulinum toxin weakens overactive muscles.
Botulinum toxin injections are usually performed with the assistance of an ultrasound machine or a muscle monitoring (electromyogram or EMG) machine to help identify muscles. Botulinum toxin injections are typically given every 3 months to avoid the formation of antibodies by the immune system which may lead to a loss of benefit from future injections.