Botulinum neurotoxin (BNT) injections are a common treatment for several types of dystonia. This therapy is used to treat to dystonia symptoms in a specific group of muscles, for example in the neck or a limb.
- What is Botulinum Neurotoxin Therapy?
Botulinum neurotoxin injections are a localized treatment to relieve dystonia symptoms. Botulinum neurotoxin (BNT), a biological product, is injected into muscles where it relaxes the muscles and reduces excessive muscle contractions. BNT is derived from the bacterium Clostridium botulinum. Ironically this is the same bacterium responsible for botulism, a disease associated with eating contaminated food. BNT is used as a therapeutic agent to block the release of chemicals that activate muscle contractions.
- How Can a ‘Toxin’ be a Medical Treatment?
Although a medication with the word “toxin” in the name may seem confusing, BNT injections have decades of research and clinical experience demonstrating that they are a safe and effective medical therapy. When used medically, BNT are transformed into a therapeutic agent by complex manufacturing processes. The doses used to treat dystonia are far less than the amount that would even begin to make a person ill from botulism.
- How do Botulinum Neurotoxin Injections Work?
When BNT is injected into muscles affected by dystonia, it blocks the neurotransmitter chemicals that signal the muscles to contract and spasm excessively. The muscle is weakened and therefore relaxes, reducing the dystonia. Prior to the introduction of BNT in the United States during the 1980s, there was essentially no treatment for focal dystonias, and generalized dystonias were managed with oral medications and irreversible brain surgery.
- Are These the Same Injections Used for Wrinkles?
Botulinum neurotoxin injections is used for both medical and cosmetic purposes. The doses and muscles injected may be vastly different, depending on the patient.
- Are There Different Types?
Seven types of BNT have been purified for medical purposes. Each is designated by a letter: A, B, C, D, E, F, G. The only types of BNT available for therapeutic purposes are A and B.
In Canada three forms of botulinum toxin is available for patients. This is botulinum toxin type A (trade names Botox®, Xeomin and Dysport).
Botox® by Allergan, Inc., Approved 1989
(Type A – onabotulinumtoxinA)Dysport™ by Ipsen, Ltd., Approved 2009
(Type A – abobotulinumtoxinA)Xeomin® by Merz Pharmaceuticals, Approved 2010
(Type A – incobotulinumtoxinA)Your doctor can recommend which brand of BNT is appropriate for you.
- What Can I Expect After the Injections?
In all but the most unusual cases, individuals receive BNT injections on an outpatient basis and there is minimal recovery time following the procedure. Some people experience soreness or bruising at the injection site. Depending on the extent of the dystonia symptoms and areas of the body injected, some individuals prefer to have someone with them to drive or accompany them on the way home following the appointment (especially individuals with blepharospasm or moderate to severe cervical dystonia), while others are comfortable resuming their day on their own. Some individuals notice a benefit just days following a BNT injection, and most will experience significant effects within about a week. It may take up to four weeks for patients to experience the full benefit of the treatment.
- Are There Side Effects?
Temporary side effects may include muscle weakness, flu-like symptoms, pain at the injection site, and dry mouth. Ask your doctor about additional side effects that may be specific to your situation. If you experience side effects, be sure to discuss them in detail with your doctor. Adjusting the dosage or site of injection may help avoid these effects in the future. Over a decade of clinical experience suggests that people who respond well to BNT therapy may continue treatment for many years without side effects from long-term use.
- Do the Injections Need to be Repeated?
Yes. BNT therapy is an ongoing treatment that must be repeated every three to four months for the majority of dystonia patients. The fact that BNT injections must be repeated is one of the advantages of the therapy. Each session of injections provides an opportunity to adjust the dose and muscles injected, therefore customizing the treatment to the individual.
As a rule injections are repeated no sooner than every three to four months as a precaution against the risk of developing antibodies to the neurotoxin. Patients who develop antibodies may not experience as much benefit as those without antibodies.
- Can I Get Botulinum Neurotoxin Injections From Any Doctor?
It is extremely important that patients receive BNT injections from an experienced and knowledgeable doctor. In general, the specialist who is trained to treat dystonia is a movement disorder neurologist. Otolaryngologists, neuro-ophthalmologists, and ophthalmologists may give BNT injections for focal dystonias that fall under their specialties, for example, laryngeal dystonia/spasmodic dysphonia and cranial dystonias.
- How is Electromyography Used with Botulinum Neurotoxin Injections?
Electromyography, or EMG, is a technique that measures muscle activity. During EMG, a small electrode needle is inserted into the muscle to measure the electrical activity of the muscle. Doctors who inject patients with BNT may use EMG to help identify the muscles and precise targets within the muscle to be treated. Individuals with some forms of dystonia, such as blepharospasm which affects the small muscles around the eyes, may not require EMG.
Ultrasound (sonography) may also be used to visualize muscles targeted for BNT injections, providing a non-invasive alternative to EMG.
- How Soon Do Botulinum Neuorotoxin Injections Begin to Work?
Some individuals notice a benefit days following a BNT injection, and most will experience significant effects within about a week. It may take two to four weeks for patients to experience the full benefit of this therapy.
- Are the Injections Painful?
Because BNT are injected into the muscles, some level of discomfort or pain can be expected. The degree of discomfort may depend on the muscles being treated, the number of injection sites, and on the individual person. Some people treated with BNT experience soreness or bruising at the injection site(s). Once the BNT begins to work (typically within a week of the injection), it often reduces dystonia-related pain.
Other Resources:
Webinar by DMRF USA on June 2, 2022 - Botulinum Neurotoxin Injections for Dystonia: Considerations for Best Results