What is botulinum toxin?
Botulinum toxin is a muscle-relaxing medication used to decrease spasticity related to multiple sclerosis (MS) and other neurological conditions.
Botulinum toxin is derived from the bacterium Clostridium botulinum and is in a class of drugs called neurotoxins. There are two types of botulinum toxin available for therapeutic use:
- Botulinum toxin type A (Botox®)
- Botulinum toxin type B (Myobloc®)
Your doctor will decide which type of botulinum toxin is more appropriate for you.
Despite the drug's effectiveness, the FDA has not yet approved the use of botulinum toxin to treat MS-related spasticity.
What is spasticity?
Spasticity refers to a wide range of involuntary muscle contractions that result in muscle spasms or stiffness. It interferes with voluntary (intentional) muscle movement, usually the muscles of the legs and/or arms.
Spasticity is the result of an imbalance in the central nervous system, caused by a trauma or disease in the brain and/or spinal cord. This imbalance causes hyperactive muscle stretch reflexes, which result in involuntary contractions and increased muscle tone.
The degree of spasticity may vary based on many factors, including infections, stress, pain, temperature, position, and time of the day. Over time, severe spasticity may cause decreased range of motion in the affected limbs.
Some doctors believe that an increased sensitivity in the parts of the muscles that are responsible for contracting (tightening), relaxing, and stretching the muscles contribute to spasticity.
How does the botulinum toxin work?
Normally, the brain sends electrical messages to the muscles so that they can contract and move. This message is transmitted to the muscle by a substance called acetylcholine. Botulinum toxin works to block the release of acetylcholine; therefore the muscle doesn't receive the message to contract.
How do I know if botulinum toxin treatment is right for me?
A doctor will perform a complete evaluation to determine if you are eligible to receive botulinum toxin therapy.
How are botulinum toxin treatments given?
Botulinum toxin is injected into the muscle. Your doctor will determine the muscle(s) in need of treatment.
If the muscles to be injected are small or difficult to reach, it may be necessary to send short electric impulses, or to record electric signals from the muscles, to ensure that the appropriate muscles are receiving the injected medication.
A very fine needle is used for the injection. Some people report minor and temporary discomfort from the injection. The medication does not sting or cause irritation after it has been injected.
You can expect the appointment to last from 1 to 2 hours.
What are the advantages of botulinum toxin?
- Improvement of discomfort related to spasticity symptoms
- In some cases, improved ability to use the affected part of the body
When will the injection take effect to improve my spasticity?
The effects of the medication begin to appear from 1 to 2 weeks after the injection. The muscles injected should then relax.
How long will the effects of the injection last?
The medication is effective for 2 to 6 months, depending on the individual.
What are the disadvantages of botulinum toxin?
- Because the benefit of botulinum toxin is limited to the injected muscles, botulinum toxin may not be a good choice of treatment when many muscles are involved or when the spastic muscles are large.
- The effect of the injections is temporary. Therefore, injections must be repeated over time to maintain the beneficial effects. Injections are not repeated more often than every 3 months to minimize the risk of developing antibodies to the botulinum toxin (see below).
What are the side effects?
Side effects of botulinum toxin include:
- Temporary weakness of the injected muscle and weakness in some nearby muscles
- Brief flu-like symptoms (these may develop 1 week after the injections and usually only last for about 1 day)
What does it mean to "develop antibodies" to botulinum toxin?
There is a slight chance that you may develop antibodies to botulinum toxin. Antibodies to botulinum toxin cause the botulinum toxin to be less effective. If this occurs, switching to the other type of toxin (for example, from type A to type B) may be helpful. To minimize the risk of developing antibodies, specific guidelines are followed to restrict the frequency of injections and the dose of medication that is injected.
Does insurance cover this therapy?
Insurance coverage varies greatly, depending on individual insurance plans. Check with your insurance company before treatment begins.
When should I call my doctor?
Call your doctor:
- If you think that the medication is not working (please wait at least 2 weeks after the injection)
- If you are experiencing side effects that you think may be related to botulinum toxin
- When the effects of the medication wear off
How will I know if the treatment is working?
You will be examined during frequent follow-up appointments to determine if the treatment is working properly. Typically, you will be re-evaluated every 3 to 6 months to determine if it is appropriate to repeat the injections.
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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. For additional written health information, please contact the Health Information Center at the Cleveland Clinic 216.444.3771 or toll-free 800.223.2273 extension 4-3771 or visit www.clevelandclinic.org. This document was last reviewed on: 2/1/2008...#2785