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Botulinum Toxin Injections

Definition, Purpose, Precautions, Description, Preparation, Risks, Normal results

Botulinum is a bacterium (Clostridium botulinum) that produces seven different toxins that can cause botulism and is also medically used to block muscle contractions.

Purpose

Botulinum toxin (Botox) injection is used in conditions of excessive and inappropriate muscle contraction, hyperhidiosis (excess sweating) in armpits and palms, spasticity (persistent states of muscle contraction), sphincter contraction, eye-movement disorders, tics and tremors, and cosmetically to treat facial lines and wrinkles.

Botox has also been explored in the treatment of chronic muscle tension and migraine headaches. The relief is likely due to the decrease in localized muscle spasms, as no direct effect of Botox on the sensory nerves has been established.

Precautions

Botulinum toxin is produced from the bacterium that causes food poisoning in humans. High doses of the toxin can be fatal; however, doses administered therapeutically are so small that harmful effects are uncommon.

Description

The number of potential applications for botulinum toxin extends to every muscle group. The first therapeutic use of Botox was in the treatment of strabismus (eyes are unable to direct towards the same object) and since then it has been used to treat a variety of involuntary muscle contractions or disorders. Its cosmetic use is the result of treatment for facial spasms where smoothing of facial lines was reported by patients. In general, 90% of injections for facial spasms are resolved satisfactorily.

Toxin type A has a duration of effect that lasts approximately three months and is the therapeutic agent of choice for most conditions.

Preparation

The dosage of Botox must be monitored and adjusted, with multiple injections showing a lower incidence of complications versus administration by one larger dose.

Risks

In over 30 years of therapeutic use in humans, botulinum toxin has proven to be remarkably safe. Difficulties associated with administration of toxin are: different patients may experience different effects at the same dose, patients new to the treatment may experience exaggerated effects at subsequent visits and/or neighboring muscles may become activated at subsequent treatments.

Additional side effects may include excessive muscle weakness at the injection site or adjacent muscles. These effects typically resolve quickly. Occasionally, patients report flu-like symptoms but they are usually self-limited.

A certain percentage of patients may also experience resistance to the toxin. The presence of circulating anti-bodies to the toxin is presumed to be the primary reason for resistance to Botox injections. Patients who have little reaction to Botox 'A' may benefit from injections using one of the other six serotypes. Using the smallest effective dose limits the likelihood of immunoresistance in unresponsive patients.

Normal results

The anticipated outcome of Botox injections is relaxation of the target muscle tissue. The pharmacological effects of botulinum toxin are typically isolated to local areas and do not result in tissue destruction or prolonged paralysis. Varying the dose can deliver a precise amount of toxin to achieve graded degrees of paralysis for the desired level of response.

Resources

BOOKS

Brin M.F. Botulinum Toxin Therapy: Basic Science and Overview of Other Therapeutic Applications Department of Neurology, Movement Disorders Program, The Mount Sinai Medical Center, New York, New York 10029.

Blitzer, A., W. J. Binder, J. Brian Boyd, and Alastair Carruthers. Management of Facial Lines and Wrinkles. Philadelphia: Lippincott Williams & Wilkins, 1999.

OTHER

Blitzer A and L. Sulica. "Botulinum toxin: basic science and clinical uses in otolaryngology." New York Center for Voice and Swallowing Disorders, St. Luke's Roosevelt Hospital Center.

Bonny McClain, DC

KEY TERMS


Antibodies—A protein developed in response to the presence of a foreign substance.

Immunoresistance—The presence of circulating antibodies.

Neuromuscular junction—Interface between motor nerve ending and muscle tissue.

Serotype—Microorganisms differing in the type of surface antigens.

Antigen—A foreign substance inducing an anti-body response within the body.

Additional topics

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