Injection of botulinum toxin (Botox) into muscles affected by dystonia can provide relief for several months at a time. Botox helps relieve involuntary contractions causing pain, twisting, abnormal posture or changes in person’s voice or speech, by causing temporary weakness in those muscles. The injections weaken muscle activity sufficiently to reduce a spasm but not enough to cause paralysis. Because each affected muscle must be injected, this is most practical when an individual has dystonia significantly affecting a specific body area, such as the hand or jaw.
It is important that a trained doctor give the shots. The physician should be familiar with the clinical features of dystonia and the involuntary movements of the person being treated. Some physicians use an electromyograph (EMG) to locate overactive muscles and to measure and record muscle activity.
Injections with the overactive muscle are done with a small needle, with one to three injections per muscle. Discomfort at the site of injections is usually temporary, and a local anesthetic may be used to minimize any pain from the shot.
In general, side effects are temporary and clear up on their own. Depending on the part of the body treated, some side effects include muscle weakness, difficulty swallowing, flu-like symptoms and soreness at the injection site. Adjusting the dosage or site of injection for future treatments may help avoid these side effects.
The effects on the muscle usually start within days of the injection, peaking in approximately four weeks and lasting two to four months.
Some individuals might benefit from the injections indefinitely. Based on more than a decade of clinical experience, patients who respond well to botulinum toxin may continue treatment over the course of many years without side effects. In some cases, a patient who has previously been successfully treated begins to experience a loss in benefit, possibly because the nature and pattern of muscle contractions may change over time. It’s also possible that a person may develop antibodies that “neutralize” the injected toxin.