Promising Therapies Using Botulinum Toxin
Migraine. Stroke. Excessive sweating. Writer’s cramp. Pain. These conditions seem to have little in common, yet they may all be effectively treated with Botulinum Toxin Type A (BT). Although some erroneously call BT a “wonder drug”, it has made its mark in pain treatment and likely has potential to be more widely used.
How Does It Work?
The active ingredient in BT is a purified form of Botulinum Toxin type A, a naturally occurring protein generated by the bacterium, Clostridium Botulinum. It grows where there is very little oxygen such as inside a can. When botulinum toxin (BT) gets into the body through eating contaminated food, for example, it inhibits the release of acetylcholine, a biochemical that helps transfer electrical impulses from nerves to muscles. This causes the potentially fatal paralysis characteristic of botulism. BT is being used to treat a variety of pain problems, though it is not known exactly how it works. However it works, it has been shown to reduce pain in a variety of disorders, including migraines and tension-type headaches, cervical dystonia, and myofacial syndrome.
Uses of Botulinum Toxin
The FDA has approved BT for these indications: strabismus, blepharospasm, cervical dystonia, facial lines, and hyperhidrosis. While cervical dystonia is the only FDA approved indication that is frequently accompanied by pain, other painful syndromes have been treated with BT (see Table 1).
|Myofascial Pain Syndromes|
|Chronic Muscle Spasm|
|Low Back Pain|
|Cervical Dystonia (Torticollis)|
Headache is by far the most common reported use of BT. Myofacial pain sydromes related to head, neck, and low back are now commonly being treated. In the author’s experience, whiplash associated myofascial neck pain may respond extremely well. Chronic muscle spasm and low back pain may also respond.
Some of the clinical conditions for which BT is now used are “off-label” from the FDA approved package insert. It is, therefore, recommended that physicians utilize written, informed consent agreements for “off-label” conditions.
Why Physicians Should Try BT
Without question BT should be trialed more widely to treat pain syndromes. The following excerpt from Conn’s Current Therapy 2004 (edited by Robert E. Rakel and Edward T. Bope) provides a special summary.
“For chronic pain of muscular origin (e.g., low back pain), Botulinum toxin (BT) can provide dramatic and sustained relief lasting an average of 3 months. The author, Arnold Klein, MD, finds that botulinum toxin type A is also highly effective for the prevention of migraine headaches. These biologic agents produce muscle relaxation by blocking the neuromuscular junction. Despite their origin, they are extremely safe products that, when used correctly, are virtually free of serious side effects.”
Contraindications and Side-Effects
There are few. It should not be used in the presence of an infection at the proposed injection site. Individuals with motor neuron diseases such as amyotrophic lateral sclerosis or neuromuscular junctional disorders such as myasthenia gravis should only receive BT with caution. These patients have an increased risk of developing clinically significant complications including severe dysphagia and respiratory compromise. Within the first week following injection, localized pain, tenderness, and bruising may occur.
How to Inject BT
BT is supplied as a single use vial containing 100 units of BT. It is usually diluted with 1 cc of normal saline (0.9% sodium chloride). This dilution provides for a usual injection of 10 to 50 units for many muscles, although larger muscles may need more, especially in spasticity. Injections are usually kept to less than 0.5 cc per site, so that larger muscles might require several injection sites. Diluting 100 units in 2 cc is common for facial and scalp applications, especially if smaller numbers (such as 2.5 to 5) of units are desired. Theoretically, increasing the dilution increases the diffusion, so in larger muscles involved in spasticity, more dilute solutions are also commonly used (100 units in 4 cc saline). Note that little data exists regarding the efficacy of any particular dilution versus another. Once mixed, BT should be used within 4 hours.
BT appears to have potential as an effective pain treatment. To date, reports indicate it is safe and possibly effective in a variety of painful conditions. This author recommends that physicians consider adding BT to their pain relief armamentarium.