Reasons why soft tissue injuries can lead to intractable chronic pain

With a few exceptions, it is generally anticipated that individuals experiencing acute pain after damage to soft tissues will go on make a full recovery with no long-term consequences. This article looks at why some claimants (and indeed non-claimants) do not get better as expected and go on to experience intrusive chronic pain and functional restriction.

How common is it in litigation?

Acute soft tissue/musculoligamentous injury causing ongoing pain that persists for longer than expected by orthopaedic experts is a common scenario in medicolegal practice. Examples include whiplash injuries in a road traffic collisions and soft tissue sprains/strains sustained at work.

Pain becomes ‘chronic’ after it persists for more than three months, but ultimately, most cases of chronic pain after soft tissue injury do eventually resolve even if it takes significantly longer than expected. However, a small proportion of individuals (but medicolegally important due to the associated high value claims) do go on to develop a much more complex clinical presentation, with severe, intrusive and intractable chronic pain associated with marked functional restriction and disability both at home and at work.

What’s the usual prognosis for a soft tissue injury?

Medically minor soft tissue damage should resolve within a matter of a few days to weeks, perhaps a few months at the most, which is the prognosis commonly stated by orthopaedic experts. More severe soft tissue injuries might certainly take longer, but in the vast majority of cases, intrusive and functionally significant pain will resolve within 6-12 months of onset, provided good psychosocial circumstances prevail.

What are the reasons for the claimant developing ongoing intrusive and functionally significant chronic pain?

Pain management experts commonly have to explain to the court why a claimant has not have progressed along the expected clinical paradigm towards a substantial or complete recovery.

The experience of pain after soft tissue injury not only arises out of the presence of biological factors, such as the tissue damage and associated inflammatory responses, but it also arises out of the interaction between those biological factors and prevailing non-physical factors, which might include the individual’s emotional response to the injury and its impact with or without a formal psychiatric/psychological diagnosis.

Psychological factors that influence chronic pain presentations

Important psychological factors that influence presentations with chronic pain include pre-existing diagnoses such as anxiety, depressive and somatic symptom disorders; primary index-accident-related diagnoses such as PTSD (i.e. conditions directly caused by the accident itself) and secondary index-accident-related diagnoses such as anxiety, depressive and somatic symptom disorders (i.e. conditions caused by the consequences of the accident, such as chronic pain, physical disability, and socioeconomic losses etc.).

Using the biopsychosocial model

This biopsychosocial model provides Pain Management Experts with a means of explaining to the courts why chronic pain is often so much more severe, physically disabling and long lasting in those individuals who experience emotional/psychological problems, such as high levels of anxiety and/or depressed mood and/or intrusive post-traumatic symptoms and/or ongoing anger and perceived injustice.

In addition, unhelpful thought processes such as ‘catastrophisation’ (irrational thoughts where the individual believes [the injury] is much worse than it actually is) and issues such as ‘kinesiophobia’ (fear of movement) can also have a substantial negative impact on clinical outcome. Psychological symptoms, such as depression in particular but also anxiety, are known risk factors for catastrophisation and where such symptoms are evident in the pre-accident records, important elements pre-existing vulnerability might be recognised.

Individuals who have suffered seemingly very similar degrees of acutely painful soft tissue damage can consequently experience very different levels of ongoing pain and associated physical disability.

The role of the central nervous system

The key role of the nervous system in the causation and maintenance of many chronic pain syndromes is widely recognised. The nervous system can certainly become ‘sensitised’ leading to amplified responses to incoming pain signals (nociceptive input) and the misinterpretation of non-painful sensory signals as nociceptive input and ultimately pain.

Once we get inside the brain, it inevitably becomes very difficult to reliably separate primary physical mechanisms from primary psychological mechanisms. Is it genuine biological nociceptive input into the central nervous that causes the neurochemical / neurobiological changes in the brain and subsequent sensitisation to pain or do the changes and sensitisation arise substantially out of the primary psychological processes?

The importance of the psychosocial factors

Chronic pain syndromes after medically minor musculoskeletal injuries are most closely correlated to the prevalence of psychological factors, but it does not necessarily follow that those psychological factors were the cause of the condition. The recognition of important bidirectional interactions between physical and psychosocial elements often provides key insights into the understanding of a chronic pain presentation after medically minor physical injury, but attempts to separate a chronic pain condition into distinct components of ‘physical’ pain and ‘psychological’ pain is artificial and lacks a scientific basis.

In a clinical, non-medicolegal Pain Management setting, many patients present with intrusive, functionally limiting chronic pain in the absence of any specific trauma, and the formulation of a chronic pain condition after a soft tissue injury must also be informed by the claimant’s individual pre-accident history of chronic pain problems more generally.

Significant psychosocial factors that substantially preceded the index accident can be highly important when considering the prognosis “but for” the accident. However, when they have been specifically caused by the index accident itself, PTSD being a good example, it can be concluded in most circumstances that they would not have been present in the absence of that accident.

Where there are significant psychosocial factors arising out of intrusive chronic pain and functional restriction subsequent to the index accident, “but for” arguments can still become an issue if it can be successfully argued on the basis of pre-existing, naturally-occurring physical pathology that the same chronic pain and associated functional restriction would have been established in the absence of the index accident and the claimant’s chronic pain condition has simply been brought forward by the accident (acceleration).

What if you suspect exaggeration & veracity??

Whatever the precise underlying mechanisms, the close correlation between psychological factors and chronic musculoskeletal pain presentations with significant physical disability cannot be ignored. Where a claimant presents with severe and disabling chronic pain after seemingly medically minor musculoskeletal injury and there is a paucity of evidence for the prevalence of important psychological factors, the inconsistency should be recognised and matters pertaining to exaggeration and the claimant’s veracity might then need to be raised.

In summary

In some cases, acute pain does not resolve after soft tissue injury.

The central nervous system plays an important role in these cases.

Sensitisation of the nervous system to pain might arise through biological processes (‘central sensitisation’), psychiatric/psychological/emotional processes, or a combination of both.

Psychological factors usually provide key insights into presentations with chronic pain after soft tissue injuries. Severe and disabling chronic pain conditions in these cases are closely correlated with the prevalence of important psychological factors.

Both biological factors and psychiatric/psychological/emotional factors can be present before the soft tissue injury, conferring vulnerability; they can be directly caused by the index event, or they can develop subsequent to the index event.

The biopsychosocial model is important when evaluating presentations with chronic pain and the origin of the various physical and non-physical factors is important when considering the matters of causation, condition and prognosis.

The absence of significant psychological factors in claimants presenting with severe chronic pain and functional restriction after medically minor soft tissue injuries should highlight the possibility of exaggeration or feigning of pain and disability.

?Article written by:?Dr Jon Valentine MB ChB FRCA FFPMRCA FRCP, Consultant in Pain Medicine and Managing Director at Pain Expert Ltd

Dr Jon Valentine, is one of the UK’s leading expert witnesses specialising in chronic pain. He is Managing Director of Pain Expert (a ‘virtual’ medicolegal chambers). He established Pain Expert in 2012 to provide expert witnesses with the comprehensive range of services required to build and maintain a successful medicolegal practice, and also to provide those lawyers seeking to instruct Pain Management specialists in personal injury and medical negligence cases with a reliable source of suitably qualified and experienced Pain Management experts.

If you are interested in working as a pain expert witness, or you are an instructing lawyer looking to appoint an experienced Pain Specialist, then please get in touch www.pain-expert.org

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