Long-term elbow pain: is the brain more at fault than the tendon?

Tennis elbow (known in medical terms as lateral epicondylalgia) is a common condition that presents with pain on the outer aspect of the elbow. Despite its name, the condition is not restricted to tennis players and can affect anyone performing repetitive movements of the forearm (manual labourers, typists etc). In fact, tennis elbow affects up to 15 % of workers [1] and in many cases, symptoms persist and recur despite treatment.

Historically, tennis elbow was thought to be a problem restricted to the tendon (of the extensor carpi radialis brevis muscle) on the outer aspect of the elbow. However, in recent years a number of studies have shown symptoms in tennis elbow that do not fit with the description of this condition as a local tendon problem. For example, changes in movement and sensation are present in muscles unrelated to the condition (e.g. muscles of the upper arm), and these changes often appear in the opposite (or ‘unaffected’) arm [2-4]. The distribution of these symptoms across the midline points to a role for the brain in the persistence of elbow pain.

Consistent with this hypothesis, we have shown that the regions of the brain controlling movement of the forearm muscles have much greater activity and are more overlapped or ‘smudged’, than in people who are pain-free [5]. These brain changes seem to be associated with the duration and severity of symptoms and could explain the persistence and recurrence of symptoms in this condition [5].

Further support for this idea comes from our recent work that has shown altered inhibitory and facilitatory mechanisms, known to regulate activity and overlap in motor brain regions, in tennis elbow. Specifically, we have shown that people with tennis elbow have less inhibition and less facilitation in the motor regions of the brain [6]. Put simply, this means that the mechanisms that usually help to regulate brain activity are out of balance in tennis elbow, and this could underpin the increase in brain activity and overlap that we observe in this condition.

Although further studies are needed to determine whether changes in the brain are a cause or a consequence of long-term elbow pain, there is the possibility that treatments directed at rebalancing the brain (e.g. forms of non-invasive brain stimulation, electrical stimulation at the elbow or movement retraining) might help to alleviate symptoms in this common condition. Our research team is beginning to trial these treatments to see how useful they are in people with tennis elbow.

Passionate about pain and the brain? Want to contribute to our understanding of why some people get persistent pain and help design new treatments?

If you have musculoskeletal pain (of any form – e.g. elbow, back, knee) and live in Sydney contact us to find out about what research is on-going and that is looking for volunteers.

PhD Scholarship available

We are also looking for a highly motivated individual to undertake a full-time PhD scholarship (fully funded for 3 years) with our team. You will join an active research group at Western Sydney University (Brain Rehabilitation and Neuroplasticity Unit), benefiting from engagement with top researchers in the fields of brain plasticity and pain. You will gain skills and knowledge in transcranial magnetic stimulation to measure neuroplasticity in the human brain, neuronavigation, phlebotomy, central sensitisation, pharmacology and musculoskeletal pain. For more information or to apply, please send a CV to s.schabrun@uws.edu.au.

About Siobhan Schabrun

Siobhan M SchabrunSiobhan is a NHMRC Career Development Fellow and 2014-2015 Fulbright Scholar at Western Sydney University. After blending a degree in physiotherapy with a PhD in neuroscience, she is passionate about understanding, treating and preventing persistent pain. Her research has a particular focus on that buzzword… ‘neuroplasticity’. Siobhan was the winner of the inaugural Australasian Brain Stimulation Conference joke contest – which says something about her sense of humour…

References

[1] Shiri R, Viikari-Juntura E, Varonen H, Heliovaara M. Prevalence and determinants of lateral and medial epicondylitis: a population study. Am J Epidemiol. 2006;164(11):1065-74. doi: 10.1093/aje/kwj325. PubMed PMID: 16968862.

[2] Bisset LM, Russell T, Bradley S, Ha B, Vicenzino BT. Bilateral sensorimotor abnormalities in unilateral lateral epicondylalgia. Arch Phys Med Rehabil. 2006;87(4):490-5. doi: 10.1016/j.apmr.2005.11.029. PubMed PMID: 16571387.

[3] Pienimaki TT, Kauranen K, Vanharanta H. Bilaterally decreased motor performance of arms in patients with chronic tennis elbow. Arch Phys Med Rehabil. 1997;78(10):1092-5. PubMed PMID: 9339158.

[4] Alizadehkhaiyat O, Fisher AC, Kemp GJ, Vishwanathan K, Frostick SP. Upper limb muscle imbalance in tennis elbow: a functional and electromyographic assessment. J Orthop Res. 2007;25(12):1651-7. doi: 10.1002/jor.20458. PubMed PMID: 17600835.

[5] Schabrun SM, Hodges PW, Vicenzino B, Jones E, Chipchase LS. Novel Adaptations in Motor Cortical Maps: The Relationship to Persistent Elbow Pain. Med Sci Sports Exerc. 2014;Epub ahead of print. Epub Aug 6.

[6] Burns E, Chipchase LS, Schabrun SM. Altered function of intracortical networks in chronic lateral epicondylalgia. Eur J Pain. 2016. doi: 10.1002/ejp.841. PubMed PMID: 26871462.

Comments

  1. John Quintner says

    Siobahn, I suspect that both the biological mechanisms of enhanced nociception (and/or hypervigilance) and the way in which they are regulated are quite complex. When you have no idea as to how or why these mechanisms may be perturbed, then it is not appropriate to use the term “maladaptive plasticity,” unless of course you can provide neurophysiological evidence to justify the concept. But please tell me if you think my understanding of neuroscience is out of date.

  2. John Quintner says

    If such a system actually existed, I very much doubt that it would function along the lines of linear determinism.

  3. I would love to know the joke that won her the contest!

    Siobhan Reply:

    That’s top secret Craig! Can’t give away my material….

    Siobhan

  4. Nick Muray says

    I suspect it means ” restore the ratios and/or intensity levels and/or excitiability of cortical representation of the elbow region in a sensory and motor sense to their pre-chronic-pain levels”.

    But I would like Siobhan’s perspective too!

  5. John Quintner says

    Siobhan, when you said “rebalance the brain” what exactly did you mean?

    Siobhan Reply:

    Hi John,

    Apologies for the delay. I did respond to this yesterday but it doesn’t look like it posted so just in case…

    Our research has shown that there is greater activity and overlap in the motor regions of the brain in people with tennis elbow, along with too little inhibition. This suggests that these mechanisms are out of balance in this common condition. Treatments that can rebalance these mechanisms (i.e. reduce the overactivity and overlap in the motor brain regions and restore normal inhibition) might be helpful in alleviating symptoms.

    Does that help clarify the statement around rebalancing the brain?

    Siobhan

    John Quintner Reply:

    Not really. When you allude to the brain being “out of balance,” I immediately think of the simplistic theory of Yin & Yang.

    If we accept that our brains are complex dynamic self-organising, self-referential and autopoietic systems that are embedded in other bodily systems with similar properties, I fail to see how treatments can predictably hope to “rebalance” such mechanisms.

    EG Reply:

    The mind-body system appears to re-balance itself rapidly when fear is removed from the equation. Fear = negative expectation. Negative expectations may relate to:

    – aspects of the pain symptomatology
    – the diagnosis
    – personal factors, ie. work/money/relationship/family stress.

    Siobhan Reply:

    By the term ‘out of balance’ we mean that the biological mechanisms that control inhibition (usually via the neurotransmitter GABA) and those that control excitation (usually glutamate) in the brain are no longer acting in concert – as they do in the brains of pain-free individuals. This allows maladaptive plasticity (‘rewiring’) in the brain and overactivity (i.e. too much excitation and not enough inhibition) that is likely related to altered movement and pain persistence. Restoring this neural balance in the brain is one method that might help to improve symptoms in people with persistent pain. Indeed, there is already evidence that restoring neural balance in conditions such as stroke can be beneficial for recovery.