Abstract and Introduction
Background: Since their introduction to clinical medicine in 1989, botulinum toxin injections have been used for many indications. First used for nonsurgical management of strabismus, botulinum toxin injections are now widely used in plastic and reconstructive surgery for aesthetic indications; however, nonaesthetic indications of botulinum toxin have grown tremendously over the past two decades and span numerous specialties, including urology, dermatology, ophthalmology, otolaryngology, gynecology, plastic surgery, general surgery, and neurology. The present review aims to highlight nonaesthetic indications of botulinum toxin that are most relevant to the plastic surgeon with an emphasis on evidence-based practice.
Methods: A PubMed search with manual reference checking was conducted to find the most relevant and influential articles on the nonaesthetic uses of botulinum toxin within the realm of adult plastic surgery. Studies were then categorized into areas of use, and quality of evidence for each category was highlighted.
Results: Botulinum toxin has numerous nonaesthetic indications in plastic surgery, including for select pain-related disorders, skeletal muscle activity disorders, exocrine gland hyperfunction, wound healing, Raynaud phenomenon, abdominal wall reconstruction, and prosthetic breast reconstruction and augmentation. Although these indications have been widely reported, high-quality evidence supporting efficacy, optimal dose, and injection protocol with randomized controlled trials is lacking in many areas.
Conclusions: Botulinum toxin is widely used in plastic surgery for a variety of nonaesthetic indications. Future studies should focus on investigating efficacy and best practice with high level of evidence research.
Botulinum toxin is a potent neurotoxin produced by the bacterium Clostridium botulinum. It causes muscle paralysis by blocking the release of acetylcholine at the neuromuscular junction. Botulinum toxin also affects the release of other neurotransmitters and neuropeptides, which has increased its uses. Seven different botulinum toxin serotypes have been reported, with several subtypes that possess unique protein sequences and distinct molecular entities. Studies have shown that variability exists in potency, receptor occupancy, spread, and immunogenicity.
All botulinum toxin products on the market are composed of the A1 serotype (botulinum toxin type A), except for a single B serotype product [Myobloc (Solstice Neurosciences, Inc., South San Francisco, Calif.)/NeuroBloc (Eisai Manufacturing Limited, Herts, United Kingdom), botulinum toxin type B], which has been shown to have lower potency in humans than in experimental animal studies. The three most widely used botulinum toxin type A products, which differ in their final formulation and potency units, are onabotulinumtoxinA (Botox; Allergan, Inc., Dublin, Ireland), abobotulinumtoxinA (Dysport; Ipsen, Paris, France), and incobotulinumtoxinA (Xeomin; Merz, Frankfurt am Main, Germany).
At present, U.S. Food and Drug Administration–approved uses in aesthetic surgery include cosmetic improvement of lines in the glabellar and lateral canthal areas. Additional off-label aesthetic uses include lateral eyebrow elevation; treatment for gummy smile; and improving rhytides surrounding the forehead, nose, midface, lower face, and neck. Nonaesthetic on-label indications include treatment of chronic migraine, spasticity, detrusor activity, and strabismus (Table 1); however, numerous other off-label nonaesthetic indications have arisen over the past two decades.[10,11] Although prior reviews have primarily explored indications for aesthetic botulinum toxin use,[12–14] this article aims to provide a comprehensive yet succinct review of the most common nonaesthetic indications for botulinum toxin in the adult population relevant to plastic surgeons, with an emphasis on evidence-based practice using levels of evidence to summarize the studies included in each subsection (Figure 1).
Overview of the wide scope of nonaesthetic botulinum toxin use. The following indications that are less commonly performed or outside the scope of plastic surgery are included in this diagram but are not further described in the text: vaginismus, prevention or treatment of salivary fistula in head and neck surgery, rhinitis, spastic entropion, and lacrimal hypersecretion. TMJ, temporomandibular joint. Printed with permission from © Mount Sinai Health System.
Plast Reconstr Surg. 2020;146(1):157-170. © 2020 Lippincott Williams & Wilkins