The Medicolegal Challenges of Fibromyalgia

27 Mar 2020

Although fibromyalgia (FM) is now widely accepted, there is still no definitive diagnostic test for the condition and the causes are not yet fully understood. Therefore, the condition presents several challenges in the medicolegal field. These are chiefly focussed around diagnosis, establishing causation and whether the symptoms reported are severe enough to cause significant disablement (1).


The major symptom of FM is widespread pain, which occurs in all four quadrants of the body (1,2). Although previous diagnostic criteria also included the presence of a certain number of specific tender points, this measure is no longer used (3). Additional symptoms include fatigue, cognitive dysfunction, mood and sleep disturbance, headache, abdominal pain and depression (1,2,4). Furthermore, there must be no other clinical cause that could account for these symptoms (2,4).  However, there is no definitive test to prove the existence of the condition (1). One major issue with diagnosing FM is that several of the symptoms presented are also associated with depression and anxiety, or with other somatic conditions which are medically unexplained, such as myalgias, sleep disturbance and chronic fatigue (2,5). Thus, some doctors remain sceptical that FM is a physical condition, viewing it more as a somatisation disorder, in which psychological distress is manifested as physical symptoms (5,6).

Furthermore, many patients report that their symptoms fluctuate over time which means that some patients may not meet the diagnostic criteria for FM all of the time (1,2). However, in the medicolegal setting the intensity of symptoms relating to impaired function is more relevant than an ‘all-or-nothing’ diagnosis. As the diagnosis of FM is often not clear-cut, the opinion of a pain specialist is preferable to that of a GP, who may not have the sufficient specialist knowledge or experience of the condition needed to exclude a diagnosis of other similar conditions (1).

Causal Events

There is no single well-defined cause of FM but many patients attribute their condition to a triggering event, often physical trauma (1,6). However, this can be difficult to demonstrate when an incident has not resulted in any physical damage to the patient. Thus, proving causation is often a central issue in many FM claims, as there may be a number of interacting factors. Aspects to consider include the nature of the triggering event, whether physical or psychological, along with any evidence of predisposition in the claimant (1). There is some indication of a genetic element to FM (1,6), with up to 25% of the blood relatives of a sufferer also receiving a diagnosis (1). It is also important to consider whether any pre-existing conditions might compromise the patient’s health and increase their vulnerability to FM. These might include a susceptible psychological status as well as previous adverse life experiences, particularly in childhood, all of which have been shown to be more commonly found in FM sufferers (1,6).

It is often alleged that some form of physical injury, such as a motor vehicle accident (MVA) or work-related incident, triggers the onset of FM although the reason why this occurs has not yet been explained. There is some evidence of over-diagnosis of FM following whiplash injuries, with the number of patients affected dropping from 14% to 8% when tender points in the neck region are excluded. In the UK, pre-collision health-seeking behaviours and somatisation, perceived injury severity, post-collision physical symptoms and older age all predicted new onset of diffuse pain in individuals involved in MVAs. By contrast, in Lithuania, where compensation for disablement is much less common, there were no reported incidences of chronic neck pain following MVA. However, it should be remembered that while it may not be possible to confirm that FM has been caused by an injury, this does not necessarily prove that it cannot be triggered in this way (1).

A recent systematic review (6) considered the evidence for a precipitating physically or psychologically traumatic event in the causation of FM from a total of 51 studies. The majority of studies that considered physical trauma reported that it was significantly associated with the onset of either chronic widespread pain or FM. Furthermore, psychological trauma was consistently more commonly found in FM patients. In addition, several studies indicated that post-traumatic stress disorder may have a mediating effect on FM. However, it should be noted that many of the studies included in this review were of low or very low quality. For ethical reasons, it is not possible to conduct randomised controlled trials, which provide the most robust source of evidence. Instead, data came from retrospective studies which are prone to various sources of bias, in particular issues with patients’ recall of events. Variations in the definition of triggering events and outcomes, due in part to the change in diagnostic criteria for FM over time, also make it difficult to compare the results of different studies. Moreover, for physical trauma, the evidence specifically relating to FM comes from a limited number of sources.

Various mechanisms have been suggested to explain the association between physical trauma and FM. One possibility is that, following spinal cord injury, chronic immune-mediated neuroinflammation then causes FM to develop (7). In the concept of central sensitisation, the central nervous system displays a prolonged or exaggerated reaction to stimuli that should not normally provoke an effect. FM patients are known to be hypersensitive to various stimuli such as pinpricks, pressure and temperature extremes, although it has been suggested that ‘central amplification’ may be a better description of the type of pain perception experienced in FM (8). Another hypothesis centres around endocrine abnormalities, such as atypical dopamine secretion in response to painful stimuli. These have been demonstrated in FM patients and it is possible that some of the symptoms of FM such as sleep disturbance, fatigue and stress are both a cause and a consequence of these abnormalities (6). Overall, it is difficult to conclusively demonstrate a temporal link between physical trauma and the development of FM because of the emotional response which often follows physical injury, as psychological factors are themselves associated with an increased risk of FM (6). Furthermore, MRI scans have demonstrated an overlap between the regions of the brain that process pain and those that are activated by psychological trauma (9). Observations of abnormal cortisol secretion in FM patients who reported former abuse support the hypothesis that a chronic reaction to ongoing psychological stress can lead to the development of FM and possibly other pain conditions (10). This is further supported by the finding that in post-traumatic stress disorder (PTSD) patients, abnormal cortisol patterns appear to be predictive of widespread pain (11). PTSD has a high prevalence among FM sufferers and when both conditions appear together, an increase in the severity of both has been reported (12).


A further consideration in medicolegal cases involving FM is whether the symptoms reported are severe enough to cause disablement and should therefore be compensated. In this respect, there is often little else to rely on than the claimant’s subjective self-report of their own symptoms. However, there is no consistent method to assess the validity of self-reported symptoms and no accurate method of establishing the reliability of subjective reporting. A patient may perceive their symptoms to be considerably more severe than a health care professional believes them to be. It is possible that a patient may indeed be suffering from severe subjective symptoms while outwardly appearing normal. However, there is also evidence that fabricating or exaggerating symptoms is relatively common in claimants alleging disability due to FM, as the disability rates associated with the condition are much higher than those observed for many other chronic illnesses (1), although more recently it has been reported that rates of malingering in FM are low and that compensation rarely results in the resolution of symptoms (6). One key issue in assessing disablement is whether a claimant has achieved the maximal medical improvement, but this can be difficult to determine in FM, where the severity of symptoms often fluctuates. Thus, determining the patient’s efforts to mitigate their illness through self-motivation and active participation may prove useful (1).

The understanding of FM has changed considerably over recent years and this raises important considerations. The dependence on subjective reports and medical assessments for diagnosis and disability assessment could be exploited by a small number of dishonest claimants. It is important that these individuals are identified, as they serve only to negatively affect legitimate sufferers. 

About the author

Dr Chris Jenner, MB BS FRCA FFPMRCA, Consultant in Pain Medicine, is highly regarded for his extensive experience and skill for all medico legal cases involving pain. He has 15 years’ experience as an expert witness and acts for both claimant and defendant. Please contact us on 0207 118 0650 or to instruct Dr Jenner or any of our other medical experts.


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