Botulinum toxin is an incredibly potent neurotoxin. Popularly sold under the brand name Botox, it is also the most popular medical cosmetic treatment in the UK, while in the US sales of the treatment exceeded $300 million in 2001¹.

Despite its popularity, most people are only aware of the cosmetic applications of Botox: removing crows' feet² and frownlines from properly aged faces. More often used as a punchline than referred to as medical treatment, Botox has a strange place in the public eye. However, even more interesting are the remarkable medical uses for this deadly neurotoxin.

What is Botulinum Toxin?

Bacteria of the species Clostridium botulinum are found in the soil and reproduce by producing spores³. Clostridium botulinum produce seven forms of neurotoxin⁴, which are among the most potent and most poisonous substances in the world. These neurotoxins (in fact, all neurotoxins) attach themselves to nerve endings. There are many different kinds of nerves, but the botulinum toxin attaches to nerves that control muscles (peripheral motor neurons). The botulinum toxin prevents the nerve from sending its chemical signal to the muscle, so in turn preventing the muscle from contracting⁵.

Potential Uses of Botulinum Toxin

If this toxin is so poisonous, how can it be helpful? There are, in fact, three major uses for botulinum toxin:

• Treating excessive muscle contraction
• Treating diseases of excessive glandular secretion, specifically drooling and sweating
• Medical cosmetic treatment, also known as 'cosmesis'

Excessive Muscle Contraction

Too much muscle contraction can happen after a stroke or a brain or spinal cord injury. Similar cases of excessive muscle spasm can also be the result of cerebral palsy or genetic diseases of nerves. These conditions cause significant physical limitations as well as profound pain. As an example of how contraction may hurt, flex your hand into a fist as hard as you possibly can. Now hold it as tightly as you can and for as long as you can. Keep squeezing harder and harder. After only a few seconds the pain may begin. Moreover, the clenched hand is limited in function compared to the relaxed hand.

Any muscle can be affected by spasm, regardless of muscle size or location. This includes the muscles of the voicebox and the eyes. Botulinum toxin treatment is indicated for several voicebox and eye disorders, specifically spasmodic dysphonia, strabismus and blepharospasm. Symptoms of these conditions include speech difficulty, poorly coordinated eye movements and eyelid tremor.

Diseases of muscle spasm are surprisingly common and can be tremendously painful and debilitating. Relaxation of the muscles in spasm can be performed mechanically, chemically or surgically. Botulinum toxin is one of these treatments. However, before chemical or surgical interventions are used, physical therapy is often employed to see if the muscles can be stretched into relaxation. In addition, there are many other methods of relaxing these muscles that are not widely used in traditional medical practice⁶.

Diseases of Excessive Sweating and Drooling

Excessive sweating and drooling are also conditions that can be addressed by botulinum toxin treatment. Botulinum toxin injections reduce the production and release of secretions from the parotid and axillary glands (which produce saliva and armpit sweat). Because of the risks involved in this procedure, it is recommended that patients exhaust all other options first.

Cosmesis

Cosmesis, or medical cosmetic treatment, is popular for reducing lines on the face caused by muscle contraction⁷. The relaxation of frequently used facial muscles (in very focused areas) will reduce the wrinkling of skin. These areas typically include the forehead, the skin near the edge of the eye and the skin near the edge of the mouth. When used in broader areas, the effect will temporarily reduce facial expression. The principles behind this form of treatment are the same as those used in larger muscles.

The Dangers of Botulinum Toxin

Contracting our muscles is certainly something we benefit from, especially the muscles of the digestive tract, the heart and the diaphragm (which allows us to breathe). If botulinum toxin were to affect these muscles, they would contract improperly or even not at all. Illness of this kind is called botulism. Botulism poisoning can occur from eating canned foods or poorly smoked meats or fish that have been contaminated with Clostridium botulinum or its spores. Tragically, this can also affect infants (but not older children or adults) who ingest contaminated honey⁸. Botulism can cause terrific gastrointestinal distress, changes in heart rhythm and paralysis of the muscles of respiration.

Other Dangers of Botulinum Toxin Treatment

As with all medicines that are injected by needle there are several general concerns: allergy to the medicine, infection of the skin where the needle is inserted and bleeding or damage to tissue by the needle. Botulinum toxin has other concerns as well. Injecting this drug into the bloodstream can be deadly, so proper technique is essential to avoid this. Thankfully, proper technique is also very easy and few (if any) injuries of this kind have been reported.

One area of concern is the length of time the medicine's effects will last. Although the toxin binds to the nerve-ending permanently, the nerve will generate a new branch to the muscle and eventually start the muscle contraction again. The effect of botulinum toxin can begin in seven to ten days and last from six weeks to more than a year, but the generally reported time of benefit is three to four months. Repeated treatment is therefore typical. There is, however, a risk of the body becoming used to the botulinum toxin and generating antibodies to it, thus preventing it from working. Because of this risk, most doctors recommend distancing botulinum toxin treatments as far apart as possible and using as little medicine as is effective. Pharmaceutical companies continue to search for the other botulinum toxins (botulinum toxin A and B are used today) in an effort to avoid this antibody formation.

Another area of concern is cost. Because of the incredible potency of botulium toxin, pharmaceutical companies use high standards for the safety and purification of the drug. This process is extremely costly. In the midwestern United States a 100-unit supply of Botox can cost the physician $500. 100 units may only treat one large muscle in the arm or two facial muscles for ten different patients. The size of the muscle contributes to the dosage required. No more than 400 units should be employed in a single patient in a single treatment (to minimise the risk of antibody formation), although some practitioners use as many as 800-900 units for patients with extensive muscle spasm.

Another risk concerns Botox's cosmetic applications. Patients may find that they do not like their appearance after a Botox injection. Extensive facial relaxation may cause loss of expression, leading to a mask-like appearance. This is more likely to occur when larger areas are treated at one time.

Botox: Useful in Many Ways

Despite the popular perception of Botox as a form of medical cosmetic treatment in the same category as facelifts and tummy tucks, there are many practical applications for this medicine. These include reducing pain, keeping children with cerebral palsy walking and allowing stroke patients to use their hands. While cosmesis helps many people feel better about themselves, the benefits of reduced muscle spasms may allow patients to live fuller lives.

Please Note: h2g2 is not a definitive medical resource. If you have any health concerns you must always seek advice from your local GP. You can also visit NHS Direct or BBC Health Conditions.