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Complex Regional Pain syndrome

Synonyms/Similar Conditions : Reflex sympathetic Dystrophy, Sudeck’s Atrophy, Algodystrophy, Neurovascular dystrophy, Post-traumatic vasomotor disorders, post-infarctional sclerodactyly, post-traumatic vasospasm, shoulder-hand dystrophy.

This is a debilitating condition of unknown cause and poorly understood mechanism that may follow an injury. It commonly affects the upper limb since this is a frequent site of injury but may affect virtually any part of the body. The condition is enigmatic and numerous descriptions have focussed on one or other of its many manifestations attributing the aetiology to equally numerous mechanisms; this has led to the adoption of many different names. The current favoured term is: Complex Regional Pain type 1 (CRPS1). ‘Causalgia’ is the name applied to Complex Regional Pain syndrome Type 2 (CRPS2), which is essentially the same syndrome following identifiable trauma to nerve.

While authors disagree on the precise list of symptoms that may be encompassed, there is agreement on the fact that the sympathetic nervous system is involved and that the condition represents a disturbance in its balance more likely in those with abnormal sympathetic reflex (this refers to the range of changes mediated by the sympathetic nervous system in response to injury. In those who develop CRPS1, there is apparent malfunction of the normal shut-off mechanisms to these responses). The sympathetic nervous system is that part of the nervous system responsible for automatic (as opposed to voluntary) functions, such as sweating, blood supply to the skin, skin secretions, hair erection, etc. as well as other vital functions such as heart rate, hormone secretion etc. Most are agreed that there is a body characteristic and psychological make-up which predisposes an individual to CRPS1.

The onset of CRPS1 is unpredictable although those who have manifested it once are more likely to do so again if provoked. It is a characteristic of the condition that the onset, severity and duration are not related to the site or severity of the provoking trauma. It can affect severely the entire upper limb following a minor cut to a digit, while it can manifest in mild form following a major crush injury.

Clinical picture

Pain is the most prominent symptom. This is frequently ‘gnawing’ or ‘burning’ in nature, constant and out of proportion to the injury. It frequently affects parts of the limb which were uninvolved in the original trauma. Thus, a wrist injury may be accompanied by pain and tenderness in the small joints of the fingers (a frequent, early sign often affecting joints uninvolved in the injury or surgery). Hyperalgesia or Allodynia (excessive tenderness) to light touch is common. The pain is often more prominent during periods of stress when the sympathetic system is in a hyperactive state.

Other features:

Swelling: This is a constant finding and, like pain, extends to uninjured parts. This worsens, rather than resolves, with time, unlike ordinary post-traumatic swelling.

Stiffness: This is an early feature. Like pain and swelling, it extends to uninjured parts, often involving the entire hand. Attempts to manipulate the part in order to resolve stiffness will provoke pain and the stiffness worsens from consequent lack of motion. Untreated, it results in permanent scarring and contracture of the joints.

Skin changes: There is a range of variable changes to the skin. The skin of the hand alters colour, often becoming livid, purple, or mottled, and frequently has a thinned, papery look, with no wrinkles. There may be excessive sweating. A common and early change in the skin is rapid growth of coarse hair. This may appear in sites which do not normally carry hairs, such as the back of a female hand. There may be marked wasting of pulp skin which produces a sign known as ‘pencil-pointing’ of the tips of the digits (a late sign).

Other changes: The affected parts of the skeleton lose mineral content and produce the condition of ‘osteoporosis’ (thinned structure of bone). This feature has attracted the separate name of Sudeck’s atrophy.

Summary:

Cardinal signs:

  • Pain and Tenderness
  • Swelling
  • Stiffness
  • Skin changes

Secondary signs:

  • Loss of bone mineral
  • Sweating and hair changes
  • Temperature changes
  • Vasomotor (blood supply) instability
  • Trophic changes (alteration of skin structure)

There is controversy over the precise picture that can be labelled CRPS1. Some have recently even questioned its existence and postulated that all CRPS is actually CRPS 2 i.e. persistent pain and debilitation from direct nerve trauma. Most will agree that all of the cardinal signs must be present, while most of the secondary signs should also be present. Some will only accept the diagnosis with corroboration by other investigations or even by the response to treatment. Sympathetic blockade (blockage of the sympathetic nervous function by injection) is employed by some as a therapeutic test in those with an incomplete spectrum of symptoms. Bone scan (mapping of the uptake of radioactive material by bone) is one confirmatory investigative test although it is relatively non-specific. There are numerous other tests which have been given variable importance by different workers (Thermography, Cold stress tests, Sudomotor tests, catecholamine tests etc…).

The diagnosis is essentially a clinical one arrived at by the detection of the above signs, which cannot be explained by the provoking trauma.

The condition goes through a number of phases, which increase in severity of symptoms. Three stages are commonly recognised: first, second and third, but these blend into a continuous spectrum. The early changes are summarised above. End stage CRPS1 is characterised by stiffness, permanent skin changes (gloss, dry, smooth skin). Pain is a less prominent feature although there may be periods when this symptom is severe and may be provoked by attempts at moving joints beyond their stiffened range and by stress. Osteoporosis (loss of bone mineral) persists.

Treatment

It is not surprising, from the degree of disagreement over the diagnosis of this condition, that there is also disagreement over treatment. In general one aims at abolishing pain as rapidly as possible and then to work on achieving a supple hand. Commonest amongst the treatments is some form of manipulation of the sympathetic nervous system supplying the affected part. Thus, it is possible to block the ganglia (groups of sympathetic nerves) in the neck to block supply to the arm. It is also possible to block the sympathetic supply to a limb by infiltrating the venous system of the limb with an agent that fixes and incapacitates sympathetic nerves. Such a drug is guanethidine and guanethidine blocks are much favoured by anaesthetists specialising in pain management. Oral therapy (tablets) which aims to diminish sympathetic activity is also employed. Amitryptiline (which in other situations is used as an antidepressant therapy) is a useful drug particularly if employed early and is taken over a protracted course. Many other modalities are available, particularly for treatment of more advanced conditions, including: surgical ablation of parts of the sympathetic nervous system, physiotherapy, massage and splinting, ‘stress’ therapy (where the hand is used for progressively heavier work), psychotherapy. Physiotherapists who specialise in management of CRPS1 will frequently employ interferential treatment and TNS (transcutaneous nerve stimulation) to abolish pain in order to permit manipulation and exercise. Encouraging improvements can be obtained by Mirror Therapy in expert hands, and in advanced cases.

It is generally agreed that:

  • The best results are obtained if the condition is diagnosed very early.
  • Treatment aims at reducing pain and swelling and only then does one employ physiotherapy to relieve stiffness.
  • The provocation of pain generally worsens the condition.
  • Sympathetic manipulation of some kind is beneficial.

Most disagreement centres on the sequence and timing of treatment and hand surgeons will each have developed their own regimes to treat this condition. In my practice, I generally aim to diagnose the condition very early and all members of my team are constantly alert to the possibility. At these early stages (a few days post injury) oral therapy with a drug such as Amitriptyline, for a minimal period of three weeks and a diminution of physical stress (including modification of physiotherapy) will frequently abort the condition virtually completely.

Those in whom the initial presentation has been missed, or who do not respond to this initial agent, move on to the next level, and my choice would be the use of interferential treatment and/or TNS to abolish pain. If these modalities relieve pain but the stiffness persists a vigorous physiotherapy programme including sequential splintage, is instituted. In some cases this will include stress loading of the hand, serial splintage, alternating between flexion and extension, and mirror therapy. In all severe/advanced cases I would prefer also to include therapy by a psychologist. Psychological support and encouragement, specialised or general, is a useful part of treatment at any stage, if it is available, since the condition can be slow to respond and consequently demoralising. It is an essential part of treatment that all concerned maintain a positive attitude to the possibility of total recovery. Nevertheless the large majority of, but unfortunately not all, patients with the condition detected early and treated appropriately, will make a total recovery.

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