Neurodynamic treatment in chronic nerve-related leg pain
An interesting aspect of running a clinical trial is that researchers nominate a primary outcome before starting the study. Because many outcomes will be measured, an occasional outcome measure may show a statistically significant result by chance alone. Therefore the researchers single out their primary outcome so that - if a significant result is obtained on that one particular outcome - it can be concluded that it is truly due to the treatment because it unlikely to be due to chance alone.
A group of researchers in Brazil followed this convention in their recent trial of neurodynamic therapy for chronic nerve-related leg pain - that is, the type of pain that often occurs in conjuction with back pain. Neurodynamic therapy involves passive or active movements, which aimed to desensitise the overly sensitised nervous system by restoring its ability to tolerate external forces such as movement and compression. Participants in the study received 4 treatments over 2 weeks, with each session lasting up to 25 minutes. The study did not find any significant effects on the primary outcomes: leg pain and disability at 2 weeks. Interestingly, however, many of the secondary outcome measures did show significant benefits!
Significant benefits on secondary outcome measures included:
- leg pain at 4 weeks was 2.4 points better on a 0—10 scale;
- low back pain at 4 weeks was 1.5 points better on a 0—10 scale;
- function at 2 and 4 weeks was better by about 5 points on a 0—30 scale; and
- global perceived effect was about 3 points better on a scale from -5 (much worse) to +5 (much better).
This generates a conundrum: the primary outcomes are non-significant, but so many secondary outcomes are significant that they are unlikely to all be due to chance alone.
Commendably, the researchers stuck to their guns and reported that the primary finding was not in favour of neurodynamic therapy, but that many of the secondary outcomes were favourable, so trials with larger samples and longer follow-up assessments should be conducted in order to determine the extent to which neurodynamic therapy might help people with chronic nerve-related leg pain.
Want to read deeper into this topic? Have a look at the free full text version of this article published in Journal of Physiotherapy!
> From: Ferreira et al., J Physiother 62 (2017) 197-202. All rights reserved to the Australian Physiotherapy Association. Click here for the online summary.