Botulinum neurotoxin (BNT) injections are a common treatment for dystonia. This therapy is used to treat dystonia symptoms in a specific group of muscles, for example, the neck, face, or a limb. Despite the popularity of this treatment for dystonia, certain important aspects of the therapy may come as a surprise to new patients.
BNT is not a chemical drug. BNT is a biological product, or biologic. Additional examples of biologics include vaccines, blood transfusion components, gene therapy, tissues, and many other medical products. BNT is derived from the bacterium Clostridium botulinum. Ironically this is the bacterium responsible for botulism, a disease associated with eating contaminated food. Complex manufacturing techniques transform by-products of the bacterium into a safe and effective therapy that is commonly used for a number of medical conditions.
There are multiple brands. Multiple brands of BNT are available in the US, each with a distinct medical name. Each brand is created from a different strain of the Clostridium botulinum bacterium. They are not interchangeable. Some dystonia patients respond better to some brands of BNT than others.
- Botox® (OnabotulinumtoxinA)
- Myobloc® (RimabotulinumtoxinB)
- Xeomin® (IncobotulinumtoxinA)
BNT interrupts communication between nerves and muscles. BNT is injected directly into muscle to block the release of chemicals that activate muscle contractions. This reduces excessive dystonic muscle contractions, and the muscle relaxes. These effects may last for 10-16 weeks.
Most people need more than one injection per appointment. BNT injections are not like a vaccine, which involve a single prick. Very large muscle groups treated with BNT will require multiple injection sites. Small muscle groups, such as the vocal cord muscles, may only require one prick of the needle.
BNT takes time to start working. Most patients feel the effects of injections in 3-10 days. It may take 2-4 weeks to experience the full benefit of treatment.
Injections must be repeated. BNT injections are an ongoing treatment that must be repeated every 3-4 months for most dystonia patients. Each session of injections provides an opportunity to adjust the dose and muscles injected, therefore customizing the treatment to the individual.
BNT may not provide 100% relief. BNT may not completely eliminate dystonia symptoms and/or pain, but the improvement can be dramatic and profoundly improve quality of life. BNT therapy may be combined with oral medications and supportive therapies for maximum symptom relief.
Several factors influence treatment results. BNT therapy must be customized to each patient’s unique symptoms and needs. Multiple factors must be in sync for successful treatment. These include:
- Appropriate dosing
- The specific muscles involved in dystonia
- The specific sites in the muscles where BNT is injected
- The skill and technique of the doctor giving the injection
- Clear communication between doctor and patient, so both parties agree on the specific symptoms treated and what to expect from treatment
Doctors may use guidance technology. Because the precision of BNT therapy is important, some doctors will use tools to help locate targets in the muscles to inject. This can include electromyography (EMG) or ultrasound. Whether a doctor uses guidance can depend on their training and experience, and muscle groups injected.
It can take up to a year to get right. Because of the many factors that determine the success of BNT injections, it may be necessary to be injected on two or three occasions before the best benefit is achieved.
The skill of the doctor giving the injections is critical. It is important to locate an appropriately trained and experienced doctor. Travel to a major movement disorder clinic may be required to access a qualified specialist. DMRF offers a searchable directory of physicians.
Many thanks to past DMRF Clinical Fellow Abhimanyu Mahajan, MD, MHS of Rush University for reviewing the content of this article.
The Dystonia Medical Research Foundation is a 501(c)(3) non-profit organization dedicated to advancing research for improved dystonia treatments and ultimately a cure, promoting awareness, and supporting the well-being of affected individuals and families.