Methods

Injections of botulinum neurotoxin should only be performed by a physician who is trained to administer this treatment. The physician needs to know the clinical features and study the involuntary movements of the person being treated. The physician doing the treatment may palpate (touch) the muscles carefully, trying to ascertain which muscles are over-contracting and which muscles may be compensating. In some instances, such as in the treatment of spasmodic dysphonia/laryngeal dystonia, a team approach including other specialists may be required.

For selected areas of the body, and particularly when injecting muscles that are difficult or impossible to palpate, guidance using an electromyograph (EMG) may be necessary. For instance, when injecting the deep muscles of the jaw, neck, or vocal cords, an EMG-guided injection may improve precision since these muscles cannot be readily palpated. An EMG measures and records muscle activity and may help the physician locate overactive muscles.

Injections into 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 is sometimes be used to minimize any discomfort associated with the injection.

It normally takes several days for the effects of the botulinum neurotoxin to become apparent. The benefit peaks in approximately four weeks and lasts three to four months. Temporary side effects for both types A and B may include muscle weakness, flu-like symptoms, pain at the injection site, and dry mouth. Patients should feel free to ask their physician about additional side effects that may be specific to the body area that is to be injected--for example, temporary difficulty swallowing may occur in patients injected for laryngeal or cervical dystonias, but is highly unlikely for someone getting injected for writer's cramp. If a patient experiences side effects, adjusting the dosage or site of injection for future treatments may help avoid these effects. There is some evidence that side effects may be more prevalent in people treated with type B.

An important difference between the different brands of botulinum neurotoxin is the number of units needed for treatment and how much toxin is in a 'unit' of each product. The units used to measure dosage are not consistent among the commercially produced toxins, and the products are not interchangeable.

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