Case 15.1

Complex regional pain syndrome

Background

Complex regional pain syndrome (CRPS) is a severe, chronic pain condition that can be triggered by a minor injury (or can even occur spontaneously), which leads to distal regional symptoms and signs. It has a long protracted course and is associated with significant disability and a reduced quality of life. The incidence from various studies is quoted between 5 and 26/100 000. Females are more affected than males (3–4:1). The incidence peaks in the 6th decade. Upper limbs are generally more affected than lower limbs (3:2). Nine out of ten cases do not have a predisposing nerve injury. It can affect more than one limb and, in certain cases, the opposite limb too. It has also been associated with asthma, migraine, MI, traumatic brain injury, osteoporosis, and ACE inhibitor intake.

Learning outcomes

1  Recognize the clinical features of CRPS

2  Outline potential management strategies for CRPS.

CPD matrix matches

2E02; 2E03

Case history

A young, motivated athlete suffered a soft tissue injury of his left ankle, whilst training. Initially, he was seen by the trauma doctors in the A&E department and was discharged home with adequate advice and analgesia. It is almost 6 months since his injury now, and he has visited various physicians, with not much relief of his pain. He has come to see you now with a sharp, burning pain in his left leg, with associated changes to the colour of the skin, decreased hair growth, and abnormal nail changes.

What are the key points you would assess from this patient’s history?

A comprehensive history should be elicited from the patient. The history should include details of the pain condition, including the onset, severity, radiation, character, alleviating and exacerbating factors, effects on sleep, social interactions, mood, and the various treatment modalities utilized and their effect on the pain problem. A requisite number of symptoms are required to diagnose CRPS in an individual, as shown in Table 15.1.

Table 15.1 CRPS diagnosis: the Budapest criteria

(A) The patient has continuing pain which is disproportionate to the inciting event.

(B) The patient has at least one sign in two or more of the categories.

(C) The patient reports at least one symptom from three or more of the categories.

(D) No other diagnosis can better explain the signs and symptoms.

Data from Harden RN, Bruehl S, Stanton-Hicks M, and Wilson PR (2007). Proposed new diagnostic criteria for complex regional pain syndrome. Pain Medicine, 8, 326–331.

A detailed examination of the area will reveal various signs associated with CRPS in this patient. A full systemic examination should also be carried out for completeness.

What clinical features may you elicit on examination?

The characteristic clinical features of CRPS involve a combination of negative (sensory loss) and positive symptoms (hyperalgesia and allodynia), similar to neuropathic pain. However, according to the new definition, they cannot be classified as neuropathic pain as described in Table 15.1. In severe cases, the limb may be distorted, and the patient may display features of neglect.

How is the diagnosis confirmed?

The physician diagnosing the case should be aware of the Budapest criteria, which have a sensitivity of 0.85 and specificity of 0.69, compared to the previous International Association for the Study of Pain (IASP) criteria which had high sensitivity, but a very low specificity, for diagnosing CRPS. The new criteria rely on history and clinical examination and any additional tests are not recommended. Other tests may be done to exclude differential diagnoses, e.g. nerve conduction studies and electromyography (EMG).

Discuss the pathophysiology of complex regional pain syndrome

There are multiple pathophysiological mechanisms involved in the progression of CRPS, and it can change with time. The following have been implicated in CRPS: inflammation, sympathetic nervous dysfunction (coupling with the sensory system and catecholamine dysfunction), genetic and psychological factors, autoimmune dysfunction, peripheral and central sensitization, and cortical plasticity and reorganization. There is a complex interplay between most of these factors, resulting in the symptoms and signs.

Outline a management strategy for this patient

There is no definitive treatment for CRPS. Patients who are diagnosed with CRPS should be managed by a multidisciplinary approach, and the following four areas should be considered, with each patient requiring individualized care. The evidence base for these strategies are elucidated in the following paragraphs:

◆  Pharmacological management (including medicines and interventions)

◆  Rehabilitation: physical and vocational

◆  Psychological therapies

◆  Self-management skills with adequate patient information and education.

Although medications are often used to manage cases of CRPS, there is either no or insufficient evidence for the use of conventional analgesics, local anaesthetics, or first- and second-line anti-neuropathic agents.

There is limited evidence for ketamine and gabapentin for short-term use. Certain free radical scavengers, like dimethyl sulfoxide (DMSO) and N-acetylcysteine (NAC), have been used with moderate evidence. DMSO is used for ‘warm’-type CRPS, and NAC for ‘cold’-type CRPS. There is insufficient evidence for the use of botulinum toxin, capsaicin cream, muscle relaxants, or benzodiazepines. Calcitonin has been used, but the evidence is not clear. There may be some benefit for the use of bisphosphonates and calcium channel blockers.

Various interventions, like percutaneous and IV sympathetic blocks, have been used; however, there is no evidence for the effectiveness of these blocks. Surgical sympathectomy has been shown to have limited evidence for pain relief. Spinal cord stimulation, when used in carefully selected patients, results in better pain scores and an improved quality of life.

Physiotherapy and occupational therapy have been shown to have a beneficial effect in the management of CRPS and have been recommended as part of multidisciplinary care. There is minimal evidence for transcutaneous electrical nerve stimulation (TENS) or rehabilitation medicine. There is a paucity of evidence for the role of psychological management. Self-management has been shown to improve confidence in patients.

Summary

CRPS has been known in the past by various names and is a debilitating chronic condition, characterized by extreme pain in the affected limb. It is associated with sensory, motor, vasomotor, and sudomotor changes and may or may not be associated with nerve injury. Patients complain of limb dysfunction and psychosocial distress. Different diagnostic criteria have been used in the past, the most recent being the Budapest criteria, which are divided into four components and have improved the management of patients suffering from CRPS.

Further reading

Body in Mind. Available at: <http://www.bodyinmind.org>.

Butler D and Moseley L (2003). Explain pain. NOI Group Publications, Adelaide.

Goebel A, Barker CH, Turner-Stokes L, et al. (2012). Complex regional pain syndrome in adults: UK guidelines for diagnosis, referral and management in primary and secondary care. Royal College of Physicians, London.

Harden RN, Bruehl S, Stanton-Hicks M, and Wilson PR (2007). Proposed new diagnostic criteria for complex regional pain syndrome. Pain Medicine, 8, 326–31.

The Knowledge Network. Chronic pain. Available at: <http://www.knowledge.scot.nhs.uk/pain.aspx>.