An Introduction to Complex Regional Pain Syndrome

11 Jun 2019

Dr Ivan Ramos-Galvez

Dr Ivan Ramos-Galvez LMS, FRCA, FFPMRCA Consultant in Pain Medicine and leading expert witness discusses the complexities that Complex Regional Pain presents to both the medical and legal profession. In this, the first of a series of articles, he looks at the origins of CRPS.

Complex regional pain syndrome (CRPS) is an extremely painful chronic neurological condition. It usually occurs after injury or surgery, although spontaneous cases are not unknown. Characteristics of the disease include pain, changes in skin temperature and appearance and swelling of the affected limb. Although these are all signs associated with trauma, in CRPS they persist for far longer than would be expected after the normal healing process has occurred. The incidence of CRPS is between 6 and 26 per 100,000 people per year, with approximately three-quarters of all cases occurring in women.

The first written description of CRPS dates back to 1812 and was made by Alexander Denmark, a British surgeon working at the Haslar Hospital in Hampshire. He presented a case report of a soldier who had suffered a gunshot wound to the shoulder. At discharge, he noted that “I always found him with the forearm bent and in supine position and supported by the firm grasp of the other hand. The pain was of a ‘burning’ nature, and so violent as to cause a continual perspiration from his face.” Denmark hypothesised that the involvement of the radial nerve in the gunshot wound was the cause of the persistent pain.

Similar cases were described among fighters in the American Civil War, when the syndrome was known as causalgia, a term which emphasised the burning pain associated with the condition. As the technique of radiology became widespread, at around the turn of the last century, it was used by a German surgeon named Sudeck to describe examples of bone atrophy in patients who had initially suffered from acute inflammation, bone fractures, ligament injury, soft tissue infection, nerve injury or herpes zoster infection. This condition, which sometimes became chronic and disabling, was termed Sudeck’s Atrophy.

During World War I, it was hypothesised that the sympathetic nervous system might be the origin of the signs and symptoms associated with CRPS. Following further research, in which blocking of the sympathetic nervous system relieved the pain, the term “reflex sympathetic dystrophy (RSD)” was introduced during the 1940s to describe the disease. At around the same time, another theory suggested that a low-grade but persistent arterial spasm appeared after soft tissue injury, which then led to the pain and other symptoms associated with CRPS, and that a better definition of RSD would be “traumatic arterial vasospasm”. However, both these definitions appear too simplistic as it is now known that only a small minority of patients develop dystrophy and the role of a simple peripheral reflex, driven by the sympathetic nervous system, remains unproven.

In the 1950s, the anaesthesiologist John Bonica suggested that RSD involved three clinical scenarios, acute, dystrophic and atrophic, which developed in sequential order. Bonica was also involved in the founding of the International Association for the Study of Pain (IASP), one aim of which was to standardise the classification of chronic pain. During meetings in 1988 and 1993, it was established that the dystrophic aspect of CRPS was of less significance than the pain element of the condition, and thus the term “complex regional pain syndrome” was derived to describe it. Criteria were also established to aid diagnosis. The definition was further divided, according to the presence (CRPS II, equivalent to causalgia) or absence (CRPS I, equivalent to RSD), of obvious nerve injury.

Although the early IASP criteria were very useful in identifying patients with CRPS, it soon became clear that they were also misdiagnosing CRPS in patients suffering from conditions with similar clinical features. For example, under these guidelines, nearly 40% of patients with diabetic neuropathy would also be classified as CRPS sufferers. In addition, the criteria depended on reported symptoms rather than more objective data. Thus, in a conference held in Budapest in 2003, the guidelines were updated to include the presence of at least two clinical signs and at least three symptoms in each of the four following categories: sensory, vasomotor, sudomotor and motor/trophic. These guidelines became known as the Budapest, or new IASP, criteria and form the current basis for the diagnosis of CRPS.

The establishment of better diagnostic guidelines has probably led to a rise in the number of cases of CRPS that are identified. Another reason for the increase is the greater awareness and understanding of the condition among medical professionals. In the past, the view was often that sufferers were fabricating their symptoms and they were dismissed as malingerers. However, the idea that CRPS is predominately psychological in nature is now disputed by many CRPS experts, and studies have not shown any correlation between psychological factors and the development of CRPS. There is also no evidence that psychological intervention, in the absence of other treatments, can cure the condition.

Because CRPS is often associated with injury or minor surgery, as the diagnosis of this condition becomes more accepted, claims for compensation will also almost certainly increase and become relatively common. Due to the long-term nature of the disease, and the potentially devastating effects on the sufferer, claims are likely to be of high value.

Dr Ivan Ramos-Galvez is a well-established pain expert, specialising in the diagnosis and treatment of complex pain conditions. He is well regarded as an expert witness in cases involving CRPS, fibromyalgia and other pain conditions.

Please call us on 020 7118 0650 or email us at

Further Reading:


Iolascon G, de Sire A, Moretti A, Gimigliano F. Complex regional pain syndrome (CRPS) type I: historical perspective and critical issues. Clin Cases Miner Bone Metab. 2015;12(Suppl 1): 4–10.