How to diagnose chronic pain

Diagnosing chronic pain can be difficult. There are currently no easy tests to confirm its presence; therefore, it is a clinical diagnosis, based on the skill and judgment of the clinician. It is, however, an important diagnosis to make as it leads to a different strategy for symptom management, and improves overall patient outcomes.

A Challenge suited to Primary Care

It is becoming widely accepted that Chronic Pain is a condition in it’s own right. We now know that it is not simply a symptom arising from other conditions that have gone on longer than expected. It can be a real challenge to be aware of the possibility of chronic pain and secondly make a correct diagnosis. This is even more challenging when, as is usually the case, a patient has other long-term conditions. This diagnostic challenge requires all the skills and judgment that primary care clinicians are trained to use. It is often helpful to have a wider knowledge of the patient’s social, psychological and previous medical history (including their drug history). A lot of biopsychosocial information is usually available in Primary Care, and it is for this reason that GPs are very well placed to diagnose Chronic Pain.

It is generally accepted that we should consider diagnosing chronic pain once pain has persisted for 3 months after original tissue damage (as this is usually the limit of time it takes for tissues to heal). This forms the basis of the IASP (International Association for the Study of Pain) definition of chronic pain. It is now also clear that there need not be specific tissue damage that initiates pain, as pain signals themselves may be initiated by the expectation of potential damage, even without any actual tissue damage present.

Consider other causes, but balance the risk of delay

It is important to consider other ongoing causes of pain – such as persisting inflammation, infection, cancerous tissues, or ongoing structural damage. It may be necessary to consider investigations, or specialist opinion to exclude such conditions. However research suggests that prolonged periods of time (in some cases years) chasing an alternative diagnosis can be harmful to an individual’s ability to adapt well and with resilience to the impact of their chronic pain condition.

So really we should consider the diagnosis of chronic pain, or potential for the development of chronic pain, in any situation where pain is persisting beyond what we would judge a ‘normal’ timeframe, or the recovery process is not following an expected pattern of steady return to normal state for that individual.

These screening questions can be helpful in considering the diagnosis

Associated features

It is helpful to consider the wider context and effects of the persisting pain, as this gives further clues to the diagnosis and the problems that it is causing the patient. The impact of chronic pain can often lead to significant alterations in physical activity, lifestyle and a range of unhelpful behaviours. People may avoid many of the normal activities of life due to pain, fatigue, and depression linked to pain itself. It is common for many patients with chronic pain to be fearful of movement, with normal activities like walking, standing or sitting aggravating pain, some patients are excessively fearful, a condition known as kinesophobia.

Chronic pain is commonly associated with depression, IBS, migraine and other conditions, where it is suggested that there is a malfunction in the way systems work: ‘functional’ aetiology. This means that symptoms are caused by problems with the way systems work rather than specific structural defects.

Neuropathic pain

It is important to consider the co-existence of neuropathic pain within the total pain signal – many of the more resistant pains have neuropathic elements.

This sort of pain is often sharp, shooting, burning, tingling (think of describing an electric shock). It is often associated with allodynia (light touch is painful), or hyperalgesia (painful stimulus is excessively painful). Neuropathic pain elements are likely to respond, to some degree, to neuropathic pain medications.

Research findings

Over the past fifteen years there has been a tremendous knowledge gain in our understanding of the genetic, cellular and neural circuitry mechanisms underpinning persistent chronic pain states. As such, we have a plethora of new mechanisms to target with novel therapies in the years to come. Further, research is also focused and helping understanding who might be ‘vulnerable’ to developing chronic pain, giving hope for preventive measures in the future. This work has come from both pre-clinical (animal) and clinical studies. There is no single review that captures this wealth of new information and which forms the basis of ‘paradigm-shifts’ in our thinking of chronic pain as a distinct entity. Reviews tend to be focused in distinct subject areas (e.g. genetics, neuroimaging, etc), and the interested GP might like to refer to these or any recently published textbook on pain (e.g. new edition of Melzack and Wall’s “Textbook of Pain”).

Diagnosis helps patients move on and embrace treatment

It is important to make a diagnosis of chronic pain in order to consider the correct type of management treatment. As a general rule treatment for chronic pain is different to treating acute pain. In acute pain management the mainstay of treatment involves an up-titration of analgesic medication until adequate pain relief is achieved. This often involves using opiates in increasing strengths. Chronic pain management focuses on a ‘self management approach’, learning skills to adapt their lives, daily activities, helpful behaviours such as pacing, managing moods and unhelpful thinking styles and behaviour. This may be supplemented and supported by medication management but generally there is less focus on medication being the main treatment modality.

Many feel that it is essential for patients to receive a definitive chronic pain diagnosis. For many, it enables them to understand and accept their condition, and engage in learning how to manage it better, earlier and with less co-morbidty, such as depression, as well as adapt to their new state and so stay economically more prosperous. So don’t be afraid to make the diagnosis!

Further reading

  1. Tracey I, Dickenson A. SnapShot: Pain perception. Cell. 2012 Mar 16;148(6):1308-1308.
  2. von Hehn CA, Baron R, Woolf CJ. Deconstructing the neuropathic pain phenotype to reveal neural mechanisms. Neuron. 2012 Feb 23;73(4):638-52. doi: 10.1016/j.neuron.2012.02.008. Review. PubMed PMID: 22365541; PubMed Central PMCID: PMC3319438.
  3. Woolf CJ. What is this thing called pain? J Clin Invest. 2010 Nov;120(11):3742-4. doi: 10.1172/JCI45178. Epub 2010 Nov 1. Review. PubMed PMID: 21041955; PubMed Central PMCID: PMC2965006.
  4. Woolf CJ. Central sensitization: implications for the diagnosis and treatment of pain. Pain. 2011 Mar;152(3 Suppl):S2-15. doi: 10.1016/j.pain.2010.09.030. Epub 2010 Oct 18. Review. PubMed PMID: 20961685; PubMed Central PMCID: PMC3268359.
  5. Woolf CJ. Overcoming obstacles to developing new analgesics. Nat Med. 2010 Nov;16(11):1241-7. doi: 10.1038/nm.2230. Epub 2010 Oct 14. PubMed PMID: 20948534.