Using 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 control of muscle stiffness and spasticity, which can occur as a result of a number of neurological disorders.

Doctor injecting man's hand
Julia Smith / Getty Images 

What Botulinum Toxin Is

Botulinum toxin is a powerful neurotoxin produced by the bacteria, Clostridium botulinum. Historically, this was primarily known 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 1950s, 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.

How Botulinum Toxin Works

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 neurological disease, it may remain in its activated state even when it shouldn’t, unable to relax. Botulinum toxin prevents contraction by blocking the release of acetylcholine. This paralyzes the muscle, allowing it to stay in a relaxed state.

Using Botulinum Toxin for Over Active Muscles

There are several medical conditions characterized by various forms of over-activity of certain muscles, which can be relieved with botulinum toxin injections.

  • Rigidity is characterized by jerky muscles.
  • Muscle spasms occur when muscles move suddenly and unintentionally.
  • 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. 

All of these muscular movements can be very painful and may even result in injury. Rigidity, muscle spasms, spasticity, and contractures can occur due to neurological conditions such as cerebral palsy, traumatic brain or spine injury, and even some movement disorders such as Parkinson's disease. These muscle changes may occur as a result of alterations in the structure of the brain and spine, and as a result of prolonged lack of activity.

Using Botulinum Toxin for Stroke Survivors

In addition to the weakness caused by a stroke, secondary muscle changes can also affect stroke survivors. Atrophy is the loss of muscle tone and bulk that affects weakened unused muscles. After several months, stroke survivors may develop rigidity, spasms, spasticity, and contractures. This is partially caused by the long-term inactivation of muscles that are no longer able to move on their own due to the stroke.

Using Botulinum Toxin for Urinary Retention

Sometimes, botulinum toxin can help if you have problems with urinating, such as urinary retention or neurogenic bladder. In these situations, the medication is directly injected into one or more of the muscles that control the bladder to help relieve overactivity of the muscles involved in urination.

A Word From Verywell

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. If you suffer from spasms, spasticity, and contractions, targeted muscle paralysis is actually beneficial.

Botulinum toxin does not have any curative effects and it cannot help restore brain or spine function. The effect of botulinum toxin injection is temporary and injections may need to be repeated every few months.

While it is not a permanent cure, botulinum toxin can reduce some of the discomforts and it might be a useful option for you. Botulinum toxin treatment should only be injected by a trained physician who is experienced in botulinum toxin injection.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. U.S. National Library of Medicine. Botox. Last reviewed January 24, 2017.

  2. Franzén M, Hägglund G, Alriksson-Schmidt A. Treatment With Botulinum Toxin A in a Total Population of Children With Cerebral Palsy - a Retrospective Cohort Registry Study. BMC Musculoskelet Disord. 2017;18(1):520. doi:10.1186/s12891-017-1880-y

  3. Gupta AD, Chu WH, Howell S, et al. A Systematic Review: Efficacy of Botulinum Toxin in Walking and Quality of Life in Post-Stroke Lower Limb Spasticity. Syst Rev. 2018;7(1):1. doi:10.1186/s13643-017-0670-9

Additional Reading

By Heidi Moawad, MD
Heidi Moawad is a neurologist and expert in the field of brain health and neurological disorders. Dr. Moawad regularly writes and edits health and career content for medical books and publications.