Medico-Legal Aspects of Chronic Pain

June 7, 2018

By Pankaj Madan

What is Chronic Pain Disorder?

“Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage”

International Association for the Study of Pain

“Chronic Pain” can be caused by a major or minor injury or it can be a symptom of a painful chronic condition. Unfortunately, the term chronic pain is not used consistently. It can refer to pain that has been present for a defined period of say 6 months or more or it can be a shortened term meaning Chronic Pain Disorder.

Chronic Pain Disorder” is however the presentation of combined physical and psychological changes due to chronic pain.

Chronic Pain Syndrome refers to persistent pain that usually has no identifiable source and is associated with abnormal illness behaviours, including expressions of pain, that are grossly disproportionate to any underlying cause.

It is hardly surprising that given such definitions and the adversarial system in which Claimants must prove their injury and an age which brings considerable challenges in respect of the veracity of claims that scepticism exists about the existence of Chronic Pain Disorder and Chronic Pain Syndrome.  There is some basis to chronic pain problems. It is not a fictitious condition but litigation probably causes its own problems.


The Causes of Chronic Pain Disorder

Evidence based research suggests that when acute pain does not resolve within a few months, continued activation of nerves that transmit pain called “nociceptors” may result in changes in the spinal cord and brain that can lead to Chronic Pain Disorder often also called Chronic Pain Syndrome.

This mechanism also explains why there is often some delay of several months in the presentation of the condition or even why soft tissue injuries appear to improve before becoming worse and gradually deteriorating. Far from therefore being a sign of malingering, the delayed presentation of Chronic Pain may well be a sign of a genuine Claimant.


Pain is an emotion.

There is often a psychogenic element to Chronic Pain Disorder as well although the initial cause may not a psychiatric condition. There are conditions however where the pain is not thought to be organically generated at all and the conditions are purely psychosocial such as a somatoform disorder, Somatisation Disorder. These are within the specialist province of the Psychiatrist.

Chronic Pain Disorder can therefore be seen as a continuum with a purely psychological cause at one extreme and a purely organic cause (probably with a at least an element of neuropathic pain) at the other extreme. Even when the pain is organically generated however there are usually psychiatric factors also at play.


Complex Regional Pain Syndrome

This is a specific chronic Pain Condition and is very much at the organic end of the spectrum. It has a very specific definition and signs. It is sometimes seen as a result of a crushing injury or in phantom limb pain and after fracture.

The essential characteristics of the condition are pain, sensory abnormalities, swelling, stiffness, motor dysfunction, and trophic changes.

Symptoms such as temperature differences, skin colour differences such as purple or red colouring, sweating, abnormal sensitivity to heat or cold may provide a clue to the lawyer that a claimant is suffering from CRPS and to obtain specific evidence from a Chronic Pain Expert.

The specific criteria are as follows:-

Firstly there must be continuing pain which is disproportionate to any inciting event.

Secondly the Claimant must report at least 1 symptom in 3 of the 4 following categories:-

Sensory; Reports of hyperesthesia and/or allodynia

Vasomotor – Reports of temperature differences and/or skin colour changes and/or skin colour asymmetry

Sudomotor- Reports of sweating changes or asymmetry in sweating

Motor/trophic changes – Reports of decreased range of motion and/or motor dysfunction (weakness, tremors) and/or trophic changes meaning changes to the hair, nails and skin.

Finally there must be no other diagnosis that better explains the condition.

Evidence based research shows that in general, CRPS patients display significantly greater acute pain sensitivity (lower heat pain threshold) compared to non –CRPS patients. They are also significantly more sensitive to non-noxious warmth and cold. There were also measurable temperature differences between the affected side and unaffected side.


CRPS and outcome

  • 10% of Patients cannot recall any specific trauma
  • The traumatic event may be trivial
  • 7% can spread to other limbs (Provisional Damages claims!)
  • 15% do not get better after 2 years

Onset and Causation

  • Ranges from immediately to 12 months
  • Dunningham- 1976-79 Mean 18 weeks
  • Ohabayashi et al within 1 month- mean onset 18 weeks- range 8-52 weeks
  • Roganovic- 2.6 days
  • Tountas and Nogouchi- 2.5 months
  • Veldman- discounted any causation where injury is over 1 year from onset of the condition;
  • Spontaneous onset – 3-11% of cases, often in a younger group of people


It is important to remember that most cases of CRPS get better quickly. Only :-

  • 15% have pain after 2 years
  • 90% are better at 2 years

But there is a significant minority that don’t get better. These are the cases we are more likely to see in litigation. Sometimes, CRPS is replaced with CRPS “NOS” meaning not otherwise specified. It is like a residual CRPS condition from which CRPS in its true sense can flare up from time to time. Furthermore true CRPS is sometimes better but replaced with functional or psychological effects and confused with CRPS or of course sometimes there is outright exaggeration and malingering.

Complex Regional Pain Syndrome may be thought to  be often easier to manage from a lawyer’s point of view due to its organicity but it can already be seen that this is simply not the case. The condition is medico-legally very complex and often very high value. There will often be claims for Provisional Damages with an initial monetary value of more than £1 million.

The symptoms should include definite physical signs that can be seen or measured or felt. It is usually the temperature differential between the affected side and unaffected side which tends to provide the key element of the diagnosis.

However the area is just as controversial. It is possible (though it takes a considerable effort) to feign symptoms of CRPS. Singh & Davis found that hanging the arm motionless deliberately could change the temperature of the hand significantly.


The secondary gain may not be obvious

In an article by Burke “Factitious Disorders of the Upper Limb”, it was estimated that deception rates in personal injury claims generally were around 30%. This was more than deception rates in Criminal Cases! (19%).

Torniquet induced swelling must be considered. The causes may also be more subtle. Disuse or alteration of use of a  limb over time due to psychiatric effects or belief of injury can result in the development of CRPS. A self-fulfilling prophecy.

The psycho-flexed hand is a type of self-contracture with claims of disuse.

The Belle Indifference, often characterised by a smirk or smiling upon examination inappropriately is also a potential sign of a factitious disorder.



This is yet another sub-set of Chronic Pain. CWP often is called Fibromyalgia but in reality this is a sub-set of CWP. Michelle Sterling has opined that 50% of people who suffer a whiplash injury will never fully recover. 30% will remain moderately to severely disabled by their condition.

We frequently encounter cases after the initial injury such as neck soft tissue injury the development of widespread chronic pain consequent disability and distress.

The development of widespread pain following whiplash injury is well documented. The Buskila study in 1997 studied 102 patients with neck trauma. 90% had been subject to classic whiplash type injuries. A control group of 59 patients had been subjected to leg trauma. It concluded that  FMS was 13 times more frequent following neck injury than following lower extremity injury. All patients continued to be employed, and insurance claims were not increased in patients with FMS.

The study is often cited by the Claimant’s medico-legal expert but in fact the study has been criticised and to some extent discredited.

The Allaf and Dunbar Study in 2002 examined the role of physical trauma in the onset of fibromyalgia.

The results were quite startling. They found that few collision specific factors predicted the onset of widespread pain. In contrast they found that :-

  • Pre-collision health seeking behaviour was more important ie if you go to your doctor a lot you tend to do worse;
  • If you somatised before the accident with organic complaints for which no cause was found from a physical perspective those people tended to do worse;
  • If you are told or believe you are severely injured you tend to do worse;
  • Older people tend to do worse
  • In combination these factors accounted for a 20-fold difference in the onset of chronic widespread pain.
  • Furthermore the following study showed that if you took a lot of sick leave and didn’t particularly enjoy your job before the accident or event in question then you were more likely to not to return to work due to CWP.

Results from the Epifund Study showed that pre-accident psychosocial factors were much more important in predicting the development of Chronic Widespread Pain. Sick leave before the collision therefore predicted strongly more prolonged rates of recovery following whiplash.

Recent studies place more emphasis on faulty pain processing centres in the brain. In other words some studies suggest that chronic pain is likely to be a result of the magnified perception of pain due to dysfunction in one  or more of the seven pain processing parts of the brain. The brain may in turn generate a magnified inflammatory local response to the pain.  In limbs, this may be seen as CRPS.

The choice expert may no longer be the pain expert or rheumatologist but the “Neuro-Rheumatologist” or Neurologist with a special interest in pain. These studies tend to suggest that the pain is very real. Very organic. Indeed, functional MRI scanning of the brain demonstrates that the enhanced pain perception can now be visualised and demonstrated albeit this is not in use in the medico-legal context.

What makes this area even more interesting, is that Professor Frank Porreca and his team at the University of Arizona has found that there may be a link between the primordial “reward” centres in the brain and the enhanced perception of pain. This may have some implications for litigation.


Some studies have found that the most effective treatment is therefore CBT. Because the brain is neuro-plastic, (responsive in form and structure to stimulus), CBT has been shown in some cases to have some efficacy in quietening the pain centres and pathways in the brain responsible for the enhanced perception of the pain. A chance of a resolution must be taken into account in relation to future loss.

Is this malingering or vulnerability?

That is the key question in most cases.

Whether acting for the Claimant or the Defendant I usually recommend the following steps.

Obtain the Evidence

  • Obtain all the notes
  • This can be a tedious time-consuming process
  • The overlooked notes are usually the most important
  • The physiotherapy notes
  • The Counselling notes
  • The Pain Team notes
  • Why?
    • Long Consultations
    • Frequent consultations
    • Non-medico-legal
    • Claimant often tells all
    • Diagrams and detailed descriptions
    • Previous pain detailed

In one recent case in Jersey, I defended. The potential value of the claim was £1m plus claim  (with Discount rate arguments it had the potential to comfortably exceed this). I reduced  this to £350,000 by a careful analysis of causation. I had 10 lever arch files of papers. There was 1 note before the accident in the initially unobtained physiotherapy notes which demonstrated the same symptoms the claimant complained of after the accident, but 3 months BEFORE the accident. The Claimant’s experts had missed it entirely as had their Solicitors and Counsel.

Don’t overlook the potential to obtain witness statements from colleagues at work for example. Did the Claimant enjoy work? Have there been redundancies? Obtain the personnel file. Did the Claimant complain of pain at work or need special adaptations or conditions already. How much sick leave had the claimant taken from work. Examine contentions of career change to a more lucrative career a little sceptically. It seems to be a feature in many chronic pain cases that the claimant was just about to do better but for the accident, not always borne out on careful examination.

The DWP notes also may help. They take a long time to obtain and the precise form must be used and it must be the current version. Always check that you have the latest version from the website of the DWP not the one stored on your firm’s system.

Most firms of Defence solicitors or in-house departments are able to obtain specialist intelligence material. I personally have found these more useful when defending at JSM than surveillance evidence. The difference is that with Social media reports, publication and the form of words used are within the Claimant’s control. The Claimant’s self-reports of attending concerts with standing room only whilst claiming to be in chronic pain served to reduce the claim from over £600,000 to £150,000 at JSM in one recent case.

Pankaj is recommended as a leading individual in personal injury law in The Legal 500 2017. For information on his new book on Chronic Pain and CRPS click here. For information on his recently published book in relation to Subtle Brain Injury Claims please click here.