Before the 1980s, botulinum toxin was perceived as a deadly threat to humans (4). Now Botox® has nine therapeutic indications, including chronic migraines, severe axillary hyperhidrosis, and focal spasticity, along with its widely known cosmetic uses (3).
WHAT IS BOTULINUM TOXIN (AKA BOTOX)?
Botulinum toxin is a neurotoxin produced by Clostridium botulinum (a bacterium). It contains several serotypes, each of which has the ability to inhibit the release of acetylcholine (a neurotransmitter) at nerve terminals (4,8,9). When botox is injected into muscle, acetylcholine is not released, causing temporary paralysis (8). Botulinum toxin not only works at neuromuscular junctions, but has effects at four different sites in the body, including the central nervous system (e.g. cervical dystonia), autonomic nervous system (e.g. hyperhidrosis), and in pain syndromes (4).
BOTOX USES IN THE LOWER EXTREMITIES
Outside of focal spasticity, there are currently no other FDA approved indications for Botox® in the lower extremities; however, there are multiple other (off-label) uses for it that have been documented in the literature. Below is a list of four uses of botox in the lower extremity that you may have not known about.
Purpose: To reduce spastic activity, induce muscle relaxation, improve motor control and function, and to decrease pain (9).
As mentioned above, spasticity is the one FDA approved indication for Botox® in the lower extremities; however, according to the Botox® website, this only includes adult patients (3). Causes of spasticity are wide, though, and can be seen in children, as is the case with cerebral palsy.
Cerebral palsy (CP) is a non-progressive, cerebral disorder that impairs motor control and causes spasticity. This spasticity can eventually lead to contractures and deformities in the extremities (9). Treatment for CP is multifactorial, involving oral medications and several forms of therapy. Injections of botox can be started as early as 2 years of age and the effects may last up to 3-6 months. (5,9). Depending on what is being treated, the injections can be done in different locations, including the hip flexors, hamstrings, and/or calf muscles. Combination treatment with stretching, splinting, and/or casting should also be considered for optimizing outcomes (9).
#2. Plantar Fasciitis
Purpose: To reduce pain and inflammation, induce muscle relaxation, and decrease underlying muscle volume (1).
Plantar fasciitis is probably one of the most commonly diagnosed foot problems that presents to a podiatrist’s office. The pain can be present anywhere along the plantar fascia (which is the long ligament along the bottom of the foot-see picture below), but is most frequently felt near the bottom of the heel. Several treatment options are available and include rest and/or modification of activities, icing, anti-inflammatory medications, stretching exercises (when appropriate), and surgery when conservative measures fail.
In a 2005 study, the use of botox in chronic plantar fasciitis (aka plantar fasciosis) was evaluated. Patients were randomized into either the botox group, which received the botox solution, or the placebo group, which received saline injections. The injections were done near the insertion of the plantar fascia on the heel and the most tender spot along the arch. At the 8-week follow-up, there was a significant improvement noted in all four pain-related variables for the botox group (1).
Purpose: To improve excessive sweating of the feet.
Hyperhidrosis (or excessive sweating) often occurs under the arms, as well as along the palms of the hands and soles of the feet. It not only affects one personally, but it can also have professional and social implications (6). When treating hyperhidrosis of the feet with botox, several injections are performed along the bottoms of each foot. The effects take days before they are noticeable, but may last 6 months or longer. Receiving the injections can be painful, but if it helps, it may eliminate the need to use daily antiperspirants, take oral and/or topical medications, and undergo iontophoresis therapy.
#4. Muscle Contouring (i.e. Calf Hypertrophy)
Purpose: To decrease the size, volume, and circumference of the calf, leading to improved contouring of the leg (7).
The gastrocnemius muscle (made up of two heads, the medial & lateral) is the most superficial calf muscle and provides for the aesthetic appearance of the calf (2,7). Whereas men may specifically work out their calf muscles for the hope of obtaining hypertrophy, enlarged calf muscles in women is not typically viewed as an attractive feature. In rare instances, the hypertrophy can be caused by an underlying condition, but in most cases it tends to be more of a cosmetic issue. More invasive procedures for reduction of the calf muscle include partial resection of the gastrocnemius muscle or shrinking of the muscle by cutting its associated nerve (2,7). Injecting the muscle with botox is minimally invasive and has shown to have effects lasting at least 6 months (7).
Even with scientific evidence showing the benefits of botox in the lower extremities, the research is lacking of larger, well-randomized, prospective studies with many of these uses. Botox is also very expensive, and patients likely need repeat treatments. Therefore, the use of botox in the lower extremities should still be considered experimental and should not typically be done as first-line treatment. Therefore, it is important to discuss all treatment options, along with the risks and benefits of each, prior to starting anything.
Disclaimer: The above information is intended for educational purposes only and should not be construed as medical advice. Please consult your healthcare professional, should you have any questions or concerns related to your health.
1. Babcock, M. S., Foster, L., Pasquina, P., & Jabbari, B. (2005). Treatment of pain attributed to plantar fasciitis with botulinum toxin a: a short-term, randomized, placebo-controlled, double-blind study. American journal of physical medicine & rehabilitation, 84(9), 649-654.
2. Benedetto, A. V. (2006). Botulinum toxin in clinical dermatology. CRC Press. 254-267.
3. Botox® onabotulinumtoxinA injection. Allergan. (2016). Retrieved from https://www.botoxmedical.com
4. Dressler, D., & Adib Saberi, F. (2005). Botulinum toxin: mechanisms of action. European neurology, 53(1), 3-9.
5. Engström, P., Gutierrez-Farewik, E. M., Bartonek, Å., Tedroff, K., Orefelt, C., & Haglund-Åkerlind, Y. (2010). Does botulinum toxin A improve the walking pattern in children with idiopathic toe-walking?. Journal of children's orthopaedics, 4(4), 301-308.
6. Glaser, D. A., Hebert, A. A., Pariser, D. M., & Solish, N. (2007). Palmar and plantar hyperhidrosis: best practice recommendations and special considerations. CUTIS-NEW YORK-, 79(5), 18.
7. Lee, H. J., Lee, D. W., Park, Y. H., Cha, M. K., Kim, H. S., & Ha, S. J. (2004). Botulinum toxin A for aesthetic contouring of enlarged medial gastrocnemius muscle. Dermatologic surgery, 30(6), 867-871.
8. Nigam P K, Nigam A. Botulinum toxin. Indian J Dermatol 2010;55:8-14.
9. Pavone, V., Testa, G., Restivo, D. A., Cannavò, L., Condorelli, G., Portinaro, N. M., & Sessa, G. (2016). Botulinum Toxin Treatment for Limb Spasticity in Childhood Cerebral Palsy. Frontiers in pharmacology, 7.