Botulinum Toxin for Muscle Spasticity

Botulinum toxin is commonly known as botox. Botox is one of the brand names of a substance used for an injectable procedure popularized for the reduction of the appearance of fine lines and facial wrinkles. There are a number of botulinum toxin products made by different manufacturers. These are injectable solutions made with botulinum toxin for the temporary control of wrinkles.

But the use of botulinum toxin injections for cosmetic benefits is relatively new.

Botulinum toxin injections have long been used for some of the muscle changes that may occur after a stroke.

What is botulinum toxin?

Botulinum toxin is a powerful neurotoxin produced by the bacteria, clostridium botulinum. Historically, this was primarily identified as a deadly toxin that could be acquired by eating food contaminated with clostridium botulinum. The resulting disease, causing extensive nerve paralysis and muscle weakness, is called botulism. Botulism is a serious illness, resulting in life threatening weakness of muscles throughout the body, including the muscles that control vital functions such as breathing. 

After the 1950's, scientists developed the ability to isolate the toxin and carefully inject it into specifically selected muscles for the treatment of medical problems such as the muscle spasms that can occur after a stroke or as a result of other serious neurological disorders such as cerebral palsy.

 

Why is botulinum toxin used as a treatment for stroke survivors?

There are several muscle changes that can affect stroke survivors. Atrophy is the loss of muscle tone and bulk that affects weakened, unused muscles. Other ways that a stroke affects muscles include the development of rigidity, spasms, spasticity, and contractures.

Rigidity is characterized by stiff and jerky muscles. Muscle spasms occur when muscle are suddenly activated involuntarily, meaning, not on purpose. People who suffer from spasticity or contractures suffer from over-activity of certain muscles. Contractures occur when muscles are essentially locked into an activated state and also too weakened to move voluntarily.

Spasticity occurs when a muscle becomes stiff due to the long-term involuntary activation of muscles that are no longer able to move on their own due to brain or spine damage. Rigidity, muscle spasms, spasticity, and contractures can occur after a stroke due to changes in the structure of the brain and nerves. All of these muscular consequences can be very painful and may even result in injury. 

How does botulinum toxin work?

Botulinum toxin, the component from which the injectable muscle relaxant products are made, works by preventing the normal or abnormal communication between a nerve and a muscle- essentially causing paralysis of the muscle.

Botulinum toxin works at the location where a nerve sends a message to a muscle.

A nerve normally sends a message to a muscle by stimulating the release of a neurotransmitter called acetylcholine. Under normal circumstances, acetylcholine is released when a nerve is activated. Acetylcholine binds to the muscle, quickly initiating a series of events that cause the muscle to shorten, or contract. When a muscle contracts, it is in it’s activated state and that is described as 'moving the muscle.'

However, when a muscle is over-stimulated due to the damage caused by a stroke, it may remain in its activated state even when it shouldn’t, unable to relax. Botulinum toxin injections can allow muscle relaxation to occur by blocking contraction (activation.) Botulinum toxin blocks the release of acetylcholine, thus paralyzing the muscle by preventing contraction.

While the dangerous disease botulism causes paralysis of many important muscles throughout the whole body, injection of botulinum toxin is specifically targeted to the over-active muscles. For people who suffer from spasms, spasticity, and contractions, targeted muscle paralysis is actually beneficial.

The effect of botulinum toxin injection is temporary and it does not completely eliminate spasms, spasticity or contractures, but it can reduce some of the discomfort for many stroke survivors.

Botulinum toxin for urinary retention

In addition to reducing muscle spasticity, botulinum toxin can help stroke survivors who have trouble with a problem called urinary retention.

 

Botulinum toxin does not have any curative effects and it cannot help restore brain function. Botulinum toxin treatment for stroke patients should only be injected by a trained physician who is experienced in stroke care and in botulinum toxin injection.

Sources

OnabotulinumtoxinA Improves Pain in Patients With Post-Stroke Spasticity: Findings From a Randomized, Double-Blind, Placebo-Controlled Trial, Wissel J, Ganapathy V, Ward AB, Borg J, Ertzgaard P, Herrmann C, Haggstrom A, Sakel M, Ma J, Dimitrova R, Fulford-Smith A, Gillard P, J Pain Symptom Manage. 2016 Jul;52(1):17-26

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