The role of the medico-legal expert is not simply to decide whether the pain is “accident-related” or “unrelated”. The expert should identify the reasonable possible causes, assess the evidence supporting each explanation and consider whether several factors may have operated together.
Establishing the Clinical Picture.
The starting point should be a careful assessment of the claimant’s symptoms and any identifiable diagnosis. Pain may arise from a soft tissue injury, fracture, nerve damage, degenerative disease, inflammation or another recognised physical condition. In other cases, there may be features of neuropathic pain, chronic primary pain or psychological factors that are affecting the severity or persistence of symptoms.
A clear structural explanation will not always be present. Imaging may show little or no abnormality, despite the claimant continuing to experience significant pain and functional restriction. This does not necessarily mean that the symptoms are fabricated or insignificant.
The expert should distinguish between three separate questions: whether the claimant is experiencing pain, whether a medical explanation can be identified and whether the accident caused or materially contributed to the symptoms.
Considering All Reasonable Causes.
A balanced opinion should consider the factors that support the claimant’s account as well as those that may point towards an alternative explanation.
The nature of the accident and the proposed mechanism of injury should be assessed alongside the anatomical location of the symptoms. The expert should consider whether the force involved could cause the alleged injury and whether the pattern of symptoms is clinically consistent with that mechanism.
Previous medical history may be particularly important. The claimant may have experienced earlier pain in the same area, undergone previous investigations or received treatment before the accident. There may also be degenerative changes, unrelated medical conditions or later accidents that provide an alternative or additional explanation.
Lifestyle and psychological factors may also influence the presentation. Reduced activity, poor sleep, anxiety, low mood, fear of movement and physical deconditioning can all contribute to the persistence of pain after the original injury has healed.
The expert’s duty is to remain objective. A cause should not be ignored simply because it weakens the case of the party who provided the instruction.
The Importance of Chronology.
The timing and development of the symptoms can provide valuable evidence, although chronology alone does not prove causation.
The expert should establish when the pain began, whether the onset was immediate or delayed and when the claimant first sought medical attention. It is also important to identify whether similar symptoms were documented before the accident and whether there were any periods of improvement, recovery or later deterioration.
A close connection between the accident and the onset of symptoms may support causation, especially where the claimant had no previous problems affecting the same area. However, timing should still be considered alongside the accident circumstances, examination findings, records and expected recovery period.
A delay in reporting pain should not automatically be treated as evidence that the symptoms are unrelated. A claimant may initially have believed that the pain would settle, may have been concentrating on another injury or may not have considered the symptoms serious enough to justify treatment.
Equally, where the symptoms appear for the first time many weeks or months later, the expert should consider whether another event or condition provides a more likely explanation.
Pre-Existing Conditions and Degeneration.
Pre-existing degeneration is commonly identified in medico-legal cases, particularly in claims involving the neck, back, shoulders, hips and knees. The presence of degeneration does not automatically mean that the accident made no contribution.
An important distinction must be made between an underlying condition that was previously asymptomatic and a condition that was already producing pain and restriction before the accident.
Where degeneration was present but had not caused symptoms, the accident may have triggered the onset of pain or brought forward symptoms that would otherwise have developed later. Where the claimant was already symptomatic, the accident may have temporarily aggravated the condition, caused a longer-term worsening or had no material effect at all.
The expert should explain what would have happened in the absence of the accident. This may involve considering whether the claimant would have remained symptom-free, whether symptoms would have developed naturally and whether the accident accelerated that process by a meaningful period.
A conclusion that an accident caused an “aggravation” should be explained properly. The report should state what was aggravated, the extent of the worsening and whether the effects were temporary or permanent.
Multiple Factors May Operate Together.
Experts should avoid assuming that only one cause can be responsible for a claimant’s pain.
An accident may cause an initial physical injury that would ordinarily be expected to improve within a certain period. During that recovery, the claimant may become inactive, anxious about movement or concerned about causing further damage. Poor sleep, reduced fitness and low mood may then contribute to continuing symptoms.
In such a case, the original accident may remain part of the explanation, even though it is no longer the only factor maintaining the pain. The report should explain whether the possible causes operated independently, simultaneously or sequentially. One factor may have initiated the symptoms, while another became more important over time.
Experts should be cautious about assigning precise percentages to different causes unless there is a sound evidential basis for doing so. It may be more appropriate to identify the predominant cause and describe other factors as contributing or maintaining influences.
Reviewing the Documentary Evidence.
Contemporaneous medical records are often central to the causation assessment. GP notes, hospital records, physiotherapy documentation, imaging reports and prescription histories may show whether symptoms existed before the accident and how the condition progressed afterwards.
Occupational health records, sickness absence information and previous medico-legal reports may also assist where there is a dispute about earlier symptoms or functional restriction.
Medical records should nevertheless be interpreted carefully. They are not complete transcripts of every consultation, and the absence of a symptom from a brief entry does not necessarily prove that it was not present.
The claimant’s account should also be considered critically but fairly. Where the history provided during the medico-legal examination conflicts with earlier records, the discrepancy should be identified and explored. The expert should explain whether the inconsistency changes the causation opinion rather than leaving it unresolved.
Recognising the Limits of the Evidence.
There will be cases in which more than one explanation remains medically possible, and the evidence does not permit a definite conclusion.
The expert should not express greater certainty than the evidence allows. It may be appropriate to state that one cause is more likely than another while acknowledging that an alternative explanation cannot be excluded.
Where further information is required, the report should identify it. This may include missing medical records, earlier imaging, occupational health documents or an assessment by another specialist. Any provisional opinion should be clearly labelled as such, and the expert should explain whether additional evidence might alter the conclusion.
Presenting the Final Opinion.
The causation section should bring the different strands of evidence together. It should explain the most likely cause of the pain, the effect of the accident and the relevance of any pre-existing or subsequent condition.
The expert should state whether the accident caused a new injury, aggravated an existing problem, accelerated the onset of symptoms or made no material contribution. Where ongoing symptoms are no longer fully explained by the initial injury, the report should identify the factors that are now likely to be maintaining them.
A strong medico-legal opinion does not force a complex pain presentation into a single explanation. It identifies the reasonable possibilities, tests each against the history, records and clinical findings, and gives a clear account of how the conclusion was reached.
Where several causes have contributed, acknowledging that complexity will usually produce a more balanced, transparent and defensible report.
