Botulinum toxin is a purified form of the toxin that causes the food poisoning botulism. There are eight different forms of botulinum toxin that are used medically. The one most commonly used in the United States for patients with cerebral palsy is botulinum toxin A (OnabotulinumtoxinA) and is known by the trade name Botox®. When injected directly into a spastic muscle, botulinum toxin stops some of the signal getting from the nerve into the muscle. This weakens the muscle and decreases the spasticity. Botulinum toxin does not change the feeling in the area injected.
Botox® is FDA-approved for several conditions, including the treatment of spasticity in the arm and for dystonia of the neck (cervical dystonia or torticollis). It has been used safely in millions of children with cerebral palsy throughout the world since the late 1980’s; however, it is not FDA-approved for this purpose. Physicians are permitted to use Botox®, or other forms of botulinum toxin that have been FDA-approved for other populations, as they feel appropriate. This common practice is called “off-label” use.
Who may benefit
Botulinum toxin works best when spasticity is a problem in only a few muscles. Examples of its use include injection into the calf to decrease toe walking, the back of the thigh to decrease knee flexion and scissoring (crossing legs) and injection into the muscles of the arm to decrease elbow flexion.