July/August 2007
Volume 3, Issue 4

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Complex Regional Pain Syndromes

An Original Contribution by Jie Zhu, M.D.

Chronic foot and ankle pain from complex regional pain syndrome (CRPS) or reflex sympathetic dystrophy (RSD) is a disease involved in multiple organ systems, including neural, vascular, bony, and soft tissue structures. Most common cause is trauma secondary to accidental injury or surgery.

CRPS describes a consequence of trauma affecting the limbs, with or without an identifiable nerve lesion. The IASP Task Force had renamed reflex sympathetic dystrophy to “complex regional pain syndrome, type I (CRPS-I)" and causalgia to "complex regional pain syndrome, type II (CRPS-II) in 1994.

A soft-tissue injury or immobilization may cause the development of CRPS-I or but the injury is usually minor, such as a sprain, strain, or contusion, although it may follow a bone fracture or surgery to soft tissues. An injury to a large peripheral afferent nerve may provoke the development of CRPS-II.

There are no risk factors for CRPS identified from studies, which have failed to show that a specific psychological factor or personality predisposes a patient to development of CRPS.

In fact, many patients have injured the same body region multiple times in the past but for an unknown reason develop CRPS following their most recent injury. An extended period of immobilization or disuse of the involved limb following the traumatic event may prompt an individual for developing CRPS-I. Stress at the time of injury may also influence a patient to develop CRPS.

The patients with CRPS/RSD may have unilateral pain most commonly in one extremity although it can be present in any body part which may migrate to other body parts covered by skin over time. The region involved does not follow true peripheral nerve distribution or a dermatomal pattern.

The symptoms and signs of CRPS in some patients may gradually spread proximally. "mirror" symptoms and signs in the exact location on the contralateral limb can occur spontaneously for unknown reasons.

There are at least 2 signs being present such as edema (or sense of edema), skin color changes, temperature changes (hot and/or cold), increased or decreased sweating, weakness, tremors, dystonia, feeling limb disconnected from body. Abnormal physical findings can be present such as allodynia, hyperalgesia, patchy sensory deficits; temperature changes (hot and/or cold), increased or decreased sweating, weakness, tremors, dystonia. Most patients with this condition do not have sympathetically maintained pain. Dystrophic changes do not develop in most patients who have this condition. On neurologic examination, patchy sensory abnormalities to light touch, cold, and pinprick may be found within the affected region. Patients often hold the limb tightly against the body in a guarded position when CRPS occurs in an arm or hand.

There are no definitive diagnostic studies available yet for this condition. No laboratory tests are needed to make the diagnosis of this disease. The blood flow and blood pool phases may slow asymmetric uptake between limbs, while the static phase (most sensitive shows increased periarticular uptake in triple phase bone scan.

The diagnostic criteria for CRPS are strictly clinical, based solely on the history, symptoms, and physical findings.

All CRPS patients require a multidisciplinary model of care, in which a strong rehabilitative component is probably the most important feature. Studies show that early mobilization to break the cycle of sympathetic activity and pain is critical to a favorable outcome.

The mainstay of treatment in early stage is a short course of oral corticosteroids. Neuropathic pain medications such as Lyrica, Neurontin and Tricyclic antidepressants may be of benefit for neurogenic pain. Clonidine was used to relieve symptoms by altering autonomic nervous system activity.Calcitonin at high doses, 400 IU per day IM for 2 weeks, was also used with some success in early reflex sympathetic dystrophy. Sympathetic blocks are a key element to identify sympathetic mediated pain. Stellate ganglion blocks for upper limb reflex sympathetic dystrophy and lumbar sympathic ganglion blocks for lower limb are the procedures to reveal the contribution of sympathic component in the patient’s symptoms.

Other treatments may be required for pain control prior to physical therapy, such as sympathetic nerve neurolysis/ablation for sympathetic maintained pain, Lidocaine patch 5%, IV lidocaine infusion, mexiletine, opioids, Ketamine drips, spinal cord stimulation, or surgery.

Some patients with CRPS have spontaneous remission although a few may have chronic, refractory, and progressive symptoms. The most CRPS patients' symptoms may stabilize over several years.§