On Balance Magazine - Issue 20

Complex Regional Pain Syndrome (CRPS)

Dr David Rosen
Neurologist, mlcoa

Complex Regional Pain Syndrome (CRPS) is a chronic progressive medical condition characterised by severe pain, often accompanied by swelling and changes in the skin and frequently complicated by mood disorder, significant loss of function and subsequent disability. CRPS is classified into two types:

CRPS Type I (also known as reflex sympathetic dystrophy) does not have demonstrable nerve lesions.

CRPS Type II, (also known as causalgia), is associated with nerve damage.

The cause of CRPS is unknown. Precipitating factors include injury (sometimes apparently trivial injury) and surgery. In some cases there is no demonstrable injury to the original site.

The term “Reflex Sympathetic Dystrophy” was based on the theory that sympathetic overactivity was involved in the condition’s functional development. However, misuse of the term and doubts about its underlying cause, led to the present diagnostic term naming.

Cause of CRPS

The cause of CRPS is not fully understood. It is likely that some patients have abnormal pain systems which respond in a dysfunctional way to pain stimuli. As a result, susceptible people can precipitate a cycle of gradual uninhibited “wind-up” of pain circuits in the spinal cord and the brain associated with the central nervous system leading to increases in the levels of pain and distress, which commonly leads to dysfunctional mood and behaviour.

Susceptibility

CRPS can affect a person of any age. The mean age at diagnosis is 42. It is three times more frequent in females than males. It has been estimated that CRPS may occur in approximately 2-5% of those with peripheral nerve injury and 13-70% of those with hemiplegia (paralysis of one side of the body).

Symptoms

The symptoms of CRPS initially manifest near the site of an injury and usually spread beyond the original area. Symptoms may spread to involve the entire limb and, commonly, the opposite limb, and/or other appendages. Frequently CRPS is complicated by sleep, mood and behavioural disturbance.

The most common symptoms are burning and electrical like shooting pains. Other manifestations may include: abnormal sensory perception (normal stimuli may cause pain), muscle spasms, local swelling, increased sweating, changes in skin temperature and colour, softening and thinning of bones, joint tenderness or stiffness, restricted or painful movement, and changes in the nails, dry skin, and rapid shedding of skin.

Symptoms of CRPS vary in severity and duration. Moving or touching the limb is often intolerable and pain may be magnified by emotional stress. Eventually the joints may well become stiff from disuse, and the skin, muscles and bone become wasted and thinned.

Diagnosis

There is no diagnostic test for CRPS. It is diagnosed primarily from the clinical history. Investigations (radiology, nerve conduction studies, bone scans) are used to exclude other diagnoses.

Treatment

Early recognition and prompt treatment of pain and complicating factors, including mood disturbance, provide the greatest opportunity for recovery. The general strategy in CRPS treatment is often multidisciplinary, using different types of medications combined with physical therapies.

Physicians use a variety of drugs to treat CRPS, including antidepressants, nonsteroidal anti-inflammatories and anticonvulsants, as well as opioids, local nerve blocks and ketamine. These drugs have a high capacity for side effects and frequently cause drowsiness, poor concentration and impair mood and motivation.

Physical and occupational therapy works best for most patients, especially goaldirected therapy, where the patient begins from an initial point, regardless of how minimal, and then endeavours to increase activity each week.

People with CRPS often avoid using or touching the affected limb, with this inactivity exacerbating the disease and perpetuating the pain cycle. Thus, therapy is usually directed at facilitating the patient’s engagement in physical therapy, movement and stimulation of the affected areas.

Neurostimulation (spinal cord stimulator) might be surgically implanted to reduce the pain by directly stimulating the spinal cord. Implantable drug pumps may also be used to deliver pain medication directly to the cerebrospinal fluid - allowing powerful opioids to be used in much smaller doses than when taken orally. Surgical, chemical, or radiofrequency sympathectomy - interruption of the affected portion of the sympathetic nervous system - can be used as a last resort in patients. However, there is little evidence that these permanent interventions alter the outcomes for the better.

EEG Biofeedback, psychotherapy, relaxation techniques and hypnosis are adjunctive treatments that may assist coping.

Prognosis

The prognosis is more commonly better if treatment of pain and mood disturbance is begun early, ideally within three months of the first symptoms. Delayed treatment may cause irreversible changes in bone, nerve, muscle, mood and behaviour, leading to severe disability.