Complex Regional Pain Syndrome

Complex regional pain syndrome is a chronic progressive disease characterized by severe pain, swelling and changes in the skin in the involved region. Depending on presence or absence of nerve involvement it can be on of the two types.

Type I

It was formerly known as reflex sympathetic dystrophy, Sudeck’s atrophy, reflex neurovascular dystrophy or algoneurodystrophy. This type does not have a demonstrable nerve lesions.

Type II

It was formerly known as causalgia and is associated with obvious nerve damage.

Exact cause of this syndrome is not known. Injury and surgery are known predisposing factors but cases  can occur without these factors too. wrist fractures and are quite commonly associated with CRPS.
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Clinical Presentation Complex Regional Pain Syndrome

The symptoms of complex regional pain syndrome are usually spread beyond the original area of injury. Complex regional pain syndrome may involve the entire limb and sometimes other limb too.

The most common complaint is that of overall are burning and shooting pain. The pain is continuous and may be aggravated by emotional stress.

Examination may reveal

• Local swelling
• Hyperhydrosis or increased sweating
• Raised skin temperature
• Skin may look reddish due to blood profusion and can be smooth and moist to touch
• Joint tenderness and stiffness
• Skin and nail atrophy

The symptoms of complex regional pain syndrome vary in severity and duration.

Previously, it was thought that complex regional pain syndrome has three stages but the experience has taught us that the stages are neither sequential nor time limited and not every patient goes through these stages.  Therefore they are considered more like variants.

Type 1 complex regional pain syndrome

It is characterized by severe, burning pain at the site of the injury. Muscle spasm, joint stiffness, restricted mobility, rapid hair and nail growth, and vasospasm (a constriction of the blood vessels) that affects color and temperature of the skin can also occur

Type 2 complex regional pain syndrome

is characterized by more intense pain. Swelling spreads, hair growth diminishes, nails become cracked, brittle, grooved, and spotty, osteoporosis becomes severe and diffuse, joints thicken, and muscles atrophy.

Type 3 complex regional pain syndrome

is characterized by irreversible changes in the skin and bones, while the pain becomes unyielding and may involve the entire limb. There is marked muscle atrophy, severely limited mobility of the affected area, and flexor tendon contractions (contractions of the muscles and tendons that flex the joints). Occasionally the limb is displaced from its normal position, and marked bone softening and thinning is more dispersed.

Diagnosis of Complex Regional Pain Syndrome

Complex regional pain syndrome types I and II share the common diagnostic criteria shown below.

• There is a history of edema, skin blood flow abnormality, or abnormal sweating in the region of the pain since the inciting event.
• No other conditions can account for the degree of pain and dysfunction.

The two types differ only in the nature of the inciting event. Type I complex regional pain syndrome develops following an initiating noxious event that may or may not have been traumatic, while type II CRPS develops after a nerve injury.

No specific test is available for complex regional pain syndrome, which is diagnosed primarily through observation of the symptoms. Thermography, sweat testing, x-rays,  Nerve electrodiagnostics, and sympathetic blocks can be used to build up a picture of the disorder.

Diagnostic criteria for complex regional pain syndrome I

• The presence of an initiating noxious event or a cause of immobilization
• Continuing pain, allodynia [Perception of pain from a nonpainful stimulus], or hyperalgesia [Pain disproportionate to the stimulus]
• Evidence at some time of edema, changes in skin blood flow, or abnormal sudomotor activity in the area of pain
• The diagnosis is excluded by the existence of any condition that would otherwise account for the degree of pain and dysfunction.

Complex regional pain syndromeII (causalgia) is diagnosed as follows:

• The presence of continuing pain, allodynia, or hyperalgesia after a nerve injury, not necessarily limited to the distribution of the injured nerve

• Evidence at some time of edema, changes in skin blood flow, or abnormal sudomotor activity in the region of pain
• The diagnosis is excluded by the existence of any condition that would otherwise account for the degree of pain and dysfunction.

Treatment

Multimodal treatment is used in treatment of complex regional pain syndrome. A combination of medicine and physical therapies is used.

A variety of drugs are used to treat CRPS which include antidepressants, anti-inflammatory drugs,  vasodilators, GABA analogs such gabapentin and pregabalin, and alpha- or beta-blockers, and  opoid analgesics.

Physical and occupational therapy aim at  desensitizing the affected body part, restoring motion, and improving function.

Physical therapy works best for most patient. Therapy is directed at facilitating the patient to engage in physical therapy, movement and stimulation of the affected areas.

Recent studies have indicated success with Mirror Therapy. In this the affected limd is placed with in a mirror box and  the unaffected limb is reflected in such a way as to make the patient think they are looking at the affected limb. Movement of this reflected normal limb is then performed such that it looks to the patient as though they are performing movement with the affected limb. Following this movement of the normal limb, when the affected limb is moved, levels of pain are reduced and over a longer period significant changes between controls and intervention groups have been shown.

Injection of a local anesthetic and  topical lidocaine patches have been shown to be effective too.

Surgical, chemical, or radiofrequency sympathectomy [interruption of the affected portion of the sympathetic nervous system] can be used as a last resort in patients with impending tissue loss, edema, recurrent infection, or ischemic necrosis but evidence of effectiveness is not enough.

Biofeedback, psychotherapy, relaxation techniques and hypnosis  are adjunctive treatments which have been used in treatment to improve coping.

Ketamine Therapy have also been claimed to control and remit CRPS but needs more evidence.

Prognosis of Complex Regional Pain Syndrome

If the treatment is begun early good progress can be made. The prognosis is not always good in delayed cases. In extreme cases amputation might be advised to get rid of annoying and non functional limb.