Use of anatomic measurement to guide injection of botulinum toxin for the management of chronic lateral epicondylitis: a randomized controlled trial

Espandar and colleagues compared the effect of placebo and botulinum toxin for the management of chronic lateral epicondylitis in their article (1). Participants in botulinum toxin group received 60 units of botulinum toxin A reconstituted in 1mL of normal saline. They concluded that use of precise anatomic location to guide botulinum toxin injection significantly reduced pain at rest in patients with lateral epicondylitis. However, they did not specify the formulation of botulinum toxin type A (Botox, Dysport, or other preparation of botulinum toxin type A) they injected (1).

There are seven serotypes of botulinum toxin: A, B, C1, D, E, F, and G. They have different amino acid sequences, intracellular target sites, duration of action and muscular weakening efficacy (2). Till now, five therapeutic formulations of the botulinum toxin type A have been developed and manufactured for clinical use in many countries (2). One unit of botulinum toxins is the amount of intraperitoneally injected toxin that kills 50% (LD50) of a group of 20 g female Swiss-Webster mice within 3 days (2). Different species of mouse are used for assay for potency of botulinum toxins. Various commercial preparations may have different potencies and require different doses to achieve a similar clinical effect. For the most commonly used type A botulinum toxins, one unit of Botox is approximately equivalent in potency to 3 to 5 units of Dysport (2).

From comprehensive review of the literature, we found that the results of three randomized double-blind placebo-controlled researches evaluating the efficacy of botulinum toxin type A for treatment of lateral epicondylitis were inconsistent (3-6). The sites of injection, various preparations, and the dosage of botulinum toxin all influence the effect (3). It is very important to specify the preparation of botulinum toxins.

References

1.Espandar R, Heidari P, Rasouli MR, et al. Use of anatomic measurement to guide injection of botulinum toxin for the management of chronic lateral epicondylitis: a randomized controlled trial. Can Med Assoc J 2010;182:768-73.

2.Jankovic J. Botulinum toxin in clinical practice. J Neurol Neurosurg PS 2004;75:951-57.

3.Lin YC, Tu YK, Chen SS et al. Comparison between botulinum toxin and corticosteroid injection in the treatment of acute and subacute tennis elbow: a prospective, randomized, double-blind, active drug-controlled pilot study. Am J Phys Med Rehab. 2010, 89: 653-59.

4.Hayton MJ, Santini AJ, Hughes PJ, et al. Botulinum toxin injection in the treatment of tennis elbow. A double-blind, randomized, controlled, pilot study. J Bone Joint Surg Am 2005;87:503-7.

5.Wong SM, Hui AC, Tong PY, et al. Treatment of lateral epicondylitis with botulinum toxin: a randomized, double-blind, placebo-controlled trial. Ann Intern Med 2005;143:793-7.

6.Placzek R, Drescher W, Deuretzbacher G, et al. Treatment of chronic radial epicondylitis with botulinum toxin A. A double-blind, placebo- controlled, randomized multicenter study. J Bone Joint Surg Am 2007;89:255 -60.

Conflict of Interest:

None declared