Reflex Sympathetic Dystrophy

Chris Deighton¹ and Paul Davis²

¹ Derbyshire Royal Infirmary, Derby, UK

² University of Alberta, Edmonton, Canada

OVERVIEW

Reflex sympathetic dystrophy (RSD) is a descriptive term for a condition mainly affecting the limbs, with severe pain, a preceding event that might be relatively trivial in traumatic terms, and abnormal blood flow and sweating in the affected area.
Eventual structural changes to superficial and deep structures lead to atrophic, shiny skin, contractures and patchy osteoporosis around joints on X‐rays.
The cause is not clearly understood, but probably a variety of central and peripheral voluntary and involuntary neurological pathways play a part.
The diagnosis is usually clinical, although X‐rays and bone scans may show a characteristic appearance.
Treatment is empirical, but relies on pain reduction, early mobilization and restoration of function. Further randomized controlled trials are needed to improve the therapeutics of this difficult condition.

Introduction

Reflex sympathetic (osteo)dystrophy (RSD) is a descriptive term for a poorly understood clinical condition of unknown aetiology. It has also been variously termed shoulder‐hand syndrome, Sudeck’s atrophy and algodystrophy. It has often been confused and compared with causalgia, a different condition with similar clinical symptoms. Generally speaking, the more words used in the description of a condition, the less we understand that condition. In 1993, it was suggested that reflex sympathetic dystrophy be renamed ‘complex regional pain syndrome (CRPS) type I’. This change in nomenclature has done little to reassure the non‐specialist that our understanding of the condition has substantially improved. The change in terminology has also failed to catch on, so that many specialists still refer to RSD, even though it is clear that the reflexes are not necessarily involved, and the sympathetic nervous system cannot be implicated in many patients (for example, sympathetic ganglia blockade only relieves the pain in some patients).

To have the ‘full house’ clinically, the following should be present: (a) severe pain, usually starting peripherally, and working more proximally over time in a non‐dermatomal fashion (allodynia) – the pain is disproportionate to the triggering event and clinical findings (hyperpathia); (b) usually a preceding event that might be relatively trivial in traumatic terms; (c) abnormal blood flow to the affected area(usually a limb), with colour changes (blues, whites and reds) and oedema; (d) abnormal sweating in the area; (e) changes in the motor system, with weakness and some‐ times tremor; (f) eventual structural changes to superficial and deep structures leading to atrophic, shiny skin, contractures and patchy osteoporosis around joints on X‐rays.

Although diagnostic criteria have been proposed, these have not been validated and are complicated by the fact that not all features may be present at the same time and may vary in their intensity. The condition tends to affect upper limbs more commonly than lower limbs. Usually one limb is affected, but it can become bilateral, or affect another limb. It is usually most evident distally (hand and wrist, or foot and ankle), but a whole limb can be affected, such as in ‘shoulder‐hand syndrome’.

This chapter explores the following areas: What causes RSD? How is RSD diagnosed? What is the treatment of RSD?

What causes RSD?

The cause of RSD is far from understood, but it appears to involve an exaggeration of normal physiological responses and involves changes at multiple levels in the central and peripheral nervous systems. Some epidemiological features of RSD are shown in Box 20.1. Taking total knee arthroplasty as an example, a prevalence of between 0.8% and 1.2% of persistent RSD has been quoted. However, a recent prospective study suggested that 21% of patients fulfilled diagnostic criteria 1 month after operation, falling to 12.7% at 6 months, suggesting that symptoms and signs of RSD are not uncommon after operation, but persistent full‐blown disease is mercifully unusual. Figures of up to 35% and 5% have been reported for Colles’ fracture and peripheral nerve injury, respectively. The pathology of RSD is bedevilled by the lack of tissue studies, either pre‐ or post‐mortem. Limited histological investigations have suggested that microangiopathy or other vascular abnormalities may be a key driver. A crucial question that has not been satisfactorily answered is: Why do the majority of patients who suffer the potential triggers listed in Table 20.1 make a full and uneventful recovery, but a minority go on to develop RSD? A number of theories have been propounded, but revolve around peripheral mechanisms, central mechanisms and neurogenic inflammation with microvascular dysfunction. These interrelate in a series of vicious circles that result in the characteristic features of RSD, which are summarized below.

Table 20.1 Treatment modalities for RSD.

Source: Modified and simplified from Stanton‐Hicks et al. (2002)

Medical	Rehabilitation	Psychological
Medications NSAIDs Opioids Tricyclics Adrenoceptor antagonists Corticosteroids Calcitonin Neurological blocks Sympathetic Regional Epidural Neurostimulation Peripheral Epidural	Motivation Desensitization Isometric exercises Mobilization Flexibility Strength exercises	Counselling Behaviour modification Coping skills Relaxation therapy Hypnosis

Box 20.1 Some epidemiological factors in reflex sympathetic dystrophy

Triggers	Usually some noxious event such as:
	Wrist and tibial fractures (about 30% may demonstrate mild features, but only a minority go on to severe disease)
	Trauma: mild or moderate
	Rotator cuff tendonitis or subacromial bursitis
	Surgery: carpal tunnel decompression, arthroscopy, arthroplasty, lumbar spine surgery
	Central nervous system disorders: head injury, hemiplegia, spinal cord injury, neuropathy
	Myocardial infarction
	Immobilization: in any of the above may be an important factor
Sex	More common in women than men, with a ratio of 3:1 quoted
Age	Any age, although the mean in some studies is quoted as 52 years; now well recognized in children
Genetics	Some evidence to support a familial predisposition
Personality traits	No convincing evidence to support an association
Psychological factors	Some patients can have motor weakness and movement disorders relieved by placebo, nerve blocks or infusions