The bacterium can also be found in the intestinal tracts of mammals and fish and in the gills and organs of crabs and other shellfish. Such naturally occurring instances of Clostridium botulinum bacteria and spores are generally harmless. Problems only arise when the spores transform into vegetative cells and the cell population increases. At a certain point, the bacteria begin producing botulinum toxin, the deadly neurotoxin responsible for botulism.
Botulinum toxin can be injected into humans in extremely small concentrations and works by preventing signals from the nerve cells reaching muscles, therefore paralyzing them.
In order for muscles to contract, nerves release a chemical messenger, acetylcholine (a neurotransmitter), at the junction where the nerve endings meet muscle cells. Acetylcholine attaches to receptors on the muscle cells and causes the muscle cells to contract or shorten. Injected botulinum toxin prevents the release of acetylcholine, preventing contraction of the muscle cells. Botulinum toxin causes a reduction in abnormal muscle contraction, allowing the muscles to become less stiff.
Botulinum toxin is predominantly used as a treatment to reduce the appearance of facial wrinkles and fine lines.
Botulinum toxin is currently approved for the following therapeutic applications:
- Blepharospasm (spasm of the eyelids).
- Idiopathic rotational cervical dystonia (severe neck and shoulder muscle spasms).
- Chronic migraine.
- Severe primary axillary hyperhidrosis (excessive sweating).
- Strabismus (crossed eyes).
- Post-stroke upper limb spasticity.
- Detrusor (bladder wall muscle) overactivity – causing urinary
- Overactive bladder.
- Hemifacial spasm.
- Glabellar lines (frown lines between the eyebrows).
- Canthal lines (crow’s feet).
Botulinum toxin is also used off-label (not approved) for:
- Achalasia (an issue with the throat that makes swallowing difficult).
- Anal fissure and anismus (dysfunction of the anal sphincter).
- Sialorrhea (producing too much saliva).
- Allergic rhinitis (hay fever).
- Sphincter of oddi (hepatopancreatic) dysfunction (causes abdominal pain).
- Cerebral Palsy.
- Oromandibular dystonia (forceful contraction of the jaw, face, and/or tongue).
- Laryngeal dystonia (forceful contraction of the vocal cords).
Botulinum toxin is sold commercially under the names
- Botox, Vistabel, Botox cosmetic (OnabotulinumtoxinA or botulinum toxin type A)
- Dysport (AbobotulinumtoxinA or botulinum toxin type A)
- Bocouture, Xeomin (IncobotulinumtoxinA or botulinum toxin type A)
- Myobloc (RimabotulinumtoxinB or botulinum toxin type B).