Can Botox ace the pain of tennis elbow?

A single, carefully placed injection of botulinum toxin (Botox) can improve the pain of tennis elbow, researchers say. However, this treatment can cause temporary loss of movement in the third and fourth fingers, which may be an unacceptable side effect for many people.

What do we know already?

Tennis elbow happens when you damage the tendons in your lower arm, usually by moving your arm in a repetitive way, such as when playing tennis, raking leaves, or painting. It causes pain on the outside of your elbow, which often feels worse when you grasp something or twist your arm.

Tennis elbow usually gets better on its own in a few weeks, once you rest your arm and allow the tendons to heal. But occasionally, the pain lasts much longer, which may stop you playing sport or keep you off work.

Botulinum toxin (Botox) is a substance that relaxes muscles by temporarily paralysing them. It’s often injected into facial muscles to reduce wrinkles and frown lines. It’s also used for medical conditions such as multiple sclerosis, to relax rigid muscles.More recently, botulinum toxin has been tried as a treatment for tennis elbow. The aim is to relax the muscles that are putting tension on the tendons, thereby allowing the tendons to heal.

This treatment is often quite specialised, using high-tech equipment to pinpoint where to inject the toxin. Researchers have now developed a simpler method, in which the injection site is based on the length of the patient’s forearm. This new technique is easier to perform, but is it effective?

To find out, researchers enlisted 48 people who’d had tennis elbow for more than six months. Half were given a single injection of botulinum toxin, and half were given an injection of salt water (a placebo injection). People rated the intensity of their pain before and after treatment on a 100-point scale.

What does the new study say?

People given botulinum toxin saw improvement in their pain after four weeks. On average, their pain scores dropped by 30 points, compared with 12 points for the placebo group. Pain scores continued to drop during the 16-week study. The botulinum toxin group also had less pain while doing certain movements, such as pinching their thumb and index fingers together while their arm was resting on a table.

Alarmingly, all but one of the people in the botulinum toxin group had difficulty fully extending their third and fourth fingers after treatment. However, by the end of the study, everyone had regained full movement.

How reliable are the findings?

These findings should be fairly reliable. The study was a randomised controlled trial, which is the best type of study for finding out whether a treatment works. It was also a ‘double blind’ study, which means that neither the researchers nor the participants knew which treatment people had been given. This limits the effect that people’s expectations might have on the results.

However, there’s a good chance that many of the people in the botulinum toxin group guessed they’d been given the real treatment after losing some movement in their fingers. This knowledge could have influenced how they rated their pain.

The study was also quite small, and looked mostly at women. So, we need larger studies, with both men and women, to confirm these findings.

Where does the study come from?

The study was done by Iranian researchers at the Imam Khomeini Hospital Complex in Tehran. It was funded by the Vice Chancellor of Research at the Tehran University of Medical Sciences, and published in CMAJ, a journal owned by the Canadian Medical Association.

What does this mean for me?

If you’ve had tennis elbow for several months, you are no doubt eager for relief from your symptoms. Although this new technique of providing botulinum toxin injections appears promising, it’s still experimental. The loss of finger movement is a troubling side effect, especially if you frequently do finger-dependent tasks, such as typing. So, although this technique may help with pain, it won’t necessarily help you get back to normal straight away.

What should I do now?

If your tennis elbow doesn’t seem to be getting better, talk to your GP. Although botulinum toxin injections are not widely available, there are several other treatments that may improve your symptoms, including physiotherapy, exercises, arm braces, and possibly surgery.

From: 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. CMAJ. 2010.

Source:  BMJ Group, Thursday 29 April 2010, http://www.guardian.co.uk/lifeandstyle/besttreatments/2010/apr/29/can-botox-ace-the-pain-of-tennis-elbow