Complex Regional Pain Syndrome (CRPS). Why is it so controversial within litigation?

Some controversy exists regarding complex regional pain syndrome (CRPS) as a condition.?It’s a rare condition (some studies say a few as 6 in 100,000 cases).?Consequently, it should rarely be seen and diagnosed by doctors in a clinical setting.

Despite this, it’s relatively commonly diagnosed as a condition in personal injury litigation cases concerning limb injuries.

In this article, I’ll aim to answer why this is the case, unravel the controversies associated with diagnosis in litigation and how I (as an expert witness) approach CRPS litigation cases.

What is Complex Regional Pain Syndrome (CRPS)?

Complex regional pain syndrome (CRPS) is a form of chronic pain that usually affects an arm or a leg.?CRPS?typically develops after an injury such as a fracture or after surgery, but may develop following relatively mild injuries. The pain is out of proportion to the severity of the initial injury. CRPS is characterised by signs indicating changes in the nervous system of the affected area which can vary between patients and over time. CRPS is often accompanied by significant emotional distress or functional disability.

For the full ICD-11 Description, see here.

CRPS - diagnosis controversy within litigation

Diagnostic controversy in litigation is almost always linked to:

1. lack of a definitive test and
2. limited understanding of causation

There is no definitive test for CRPS, unlike a condition such as diabetes, where you simply take a blood test.?Instead, diagnosis is dependent on the patient meeting a set of diagnostic criteria, known as the Budapest Criteria.

The symptom criteria are self-reported and are reliant on the claimant being a reliable witness. Some of the observed signs such as stiffness, weakness and hypersensitivity are not necessarily objective and are reliant on the claimant being honest.

As an expert witness working on a CRPS case, this means you have to consider:

Is the patient making up the symptoms to match the Budapest Criteria? ?

The claimant can easily look up CRPS on the internet and view the Budapest Criteria and say “I’ve got that”.

All symptom criteria are self-reported and some of the observed signs, such as joint stiffness, decreased range of movement and sensitivity can have high levels of subjectivity. So, it’s not difficult for a claimant to meet the Budapest Criteria, without showing any truly objective clinical signs.

Therefore, you have to consider if the claimant is being truthful, or if they are making it up. For example, are the symptoms and signs merely caused by the patient not using the limb, which then becomes cooler, discolored and sometime a bit swollen, rather than new pathology? It is recognised that some people are able to consciously or subconsciously induce clinical features that make their limb appear as if they have CRPS.

Was the initial diagnosis incorrect?

It’s important to consider who made the diagnosis before it reached the Pain Management Expert Witness. Misdiagnosis is common, particularly if it is made by someone who works outside the specialty of pain management. I’ve had cases where the initial diagnosis was made by a clinician who had no background in pain management. They couldn’t explain the patient’s symptoms (due to lack of underlying known pathology) so they labeled it as CRPS. The condition is so rare, they didn’t really know how to diagnose it correctly. Consequently, they did not use the Budapest Criteria for formulating the diagnosis. I’ve even seen the condition referred to in these initial reports as ‘Chronic’, rather than Complex Regional Pain Syndrome!?

How as an expert witness do you reach a definitive diagnosis for CRPS?

Obtaining a definitive diagnosis is easier depending on the type of CRPS that has been established.

Type 1. Is where there is no associated discrete peripheral nerve damage. Often there has been a relatively minor sprain/injury which has then led to CRPS developing.?A significant proportion of medicolegal involve Type 1 cases.

Type 2. Is where there is associated discrete peripheral nerve damage shown by physical examination, scans and/or nerve tests, which does at least clearly establish that there is a pathological element involved. ?

CRPS (NOS). In addition to Types 1 & 2, a third type of CRPS is recognised – CRPS (NOS) [Not Otherwise Specified]. This is where the patient didn’t meet the necessary three symptoms and two signs set out in the Budapest Criteria, but no other diagnosis can be made. In a clinical setting the diagnosis of CRPS is not always watertight i.e. it is not uncommon for a patient to be labeled as having CRPS, even though they do not meet all the criteria for making this diagnosis.

It’s much easier to diagnose Type 2 accurately and to conclude that the nerve got damaged, which led to a cascade of events/presentations and the timeline/sequence of presentations is clearly marked (e.g. nerve damage, swelling, colour change, hypersensitivity, stiffness, hair & nail changes and finally bone thinning).?In addition, if the patient meets all the signs and symptoms of the Budapest Criteria and their symptoms developed within 4-6 weeks of the injury, the case for making a diagnosis of CRPS is far more robust.

It’s harder to do this with Type 1, where there is no demonstrable underlying pathology present. This is the majority of CRPS litigation cases.

Reaching a definitive CRPS diagnosis isn’t just dependent on the patient meeting the Budapest Criteria symptoms and signs. They also have to meet Budapest Criteria 4, namely, Diagnosis of exclusion: No other diagnosis better explains the signs and symptoms.?

This means that you have to consider the following:

Have all other conditions that mimic CRPS been ruled out?

This could include:

• Nerve impingement
• Shingles
• Vascular conditions (although unusual)
• Arthritic condition
• Fibromyalgia
• Repetitive strain injury
• Soft tissue injury

Is the condition a psychiatric disorder?

One of the main symptoms of CRPS is pain out of all proportion to the underlying injury and this could be interpreted as falling within the realms of a diagnosis of a Somatic Symptom disorder. A Somatic Symptom disorder being a psychiatric disorder characterised by physical symptoms not fully explained by known medical reasons. Certainly, those claimants who do not have any underlying pathology to explain the development of CRPS should have an alternative diagnosis of Somatic Symptom disorder considered.?

For diagnosis in a medicolegal setting, you also have to consider:

Is it completely fictitious and are the symptoms and signs due to something else?

For example, simply the disuse of the limb, which if not used can easily become cooler, discolored, and even sensitive and swollen.

Is there something about the timing of the development of the symptoms and signs that doesn’t stack up?

Going through the medical records, often you see different symptomatology appearing during the timeline, which just doesn’t stack up. If symptoms develop several months after the injury and there is no record of objective signs having been recorded by clinicians involved in treating the claimant, then the diagnosis should be questioned. However, as part of the natural course of CRPS, there is a tendency for some of the signs and symptoms to be reduced but the pain to persist. This can make a definitive diagnosis difficult depending on at which point in the timeline they are assessed. You then have to consider that the presentation could be fictitious, and the claimant is putting on an act.

Consequently, I will only diagnose CRPS when the patient has had a detailed examination and

• the symptoms and signs of the Budapest Criteria has been fulfilled
• all other potential physical and non-physical causes have been considered and ruled out
• no other physical or psychiatric diagnosis better explains the signs and symptoms

Only then will I say “I think on balance yes, it is CRPS”.

In summary - key learnings

There is no gold standard test for CRPS and therefore the diagnosis is often dependent on self-reported symptoms and subjective signs. The role of the pain expert is to ensure that if a diagnosis of CRPS is being made, it is secure and that there is no alternative diagnosis, either physical or psychological, that would better explain the claimant’s presentation. CRPS remains a challenging condition both clinically and within the medicolegal setting.

?Article written by: Dr Mohjir Baloch, Consultant in Pain Medicine, BSc MBBS MRCP FRCA FFPMRCA. Dr Baloch is a highly experienced pain consultant with over 10 years of experience working within an exceptionally regarded multidisciplinary pain clinic at his NHS base in Frimley Park Hospital.?He is regarded as an authority in the field of pain management and is an established medicolegal expert witness. He has been providing medicolegal services since January 2014 and receives instructions from solicitors acting for claimants and defendants, as well as instructions on a joint basis.?

If you are a personal injury lawyer looking to instruct an experienced Pain Specialist, then please get in touch www.pain-expert.org