How To Diagnose And Treat The Sometimes Elusive CRPS

Jeffrey Bowman DPM MS

Chronic regional pain syndrome (CRPS) can be extremely debilitating for patients and can have a sometimes elusive diagnosis. Often, clinicians might consider someone with chronic pain to be “mental.” In fact, CRPS is truly a diagnosis of exclusion.1 The following will not be a deep and detailed discussion of CRPS. My only goal is to provide you with a little more information so you don’t always assume psychological issues are the cause of an individual’s intractable pain.

Chronic regional pain syndrome is a disorder of the extremities consisting of pain, vascular issues, swelling, decreased range of motion and skin changes.1-4 An easier definition is neuropathic pain syndrome. Over the years, CRPS has had several other names: reflex sympathetic dystrophy (RSD), causalgia and Sudeck’s atrophy. Researchers originally described CRPS as a burning pain that Civil War soldiers were experiencing.4

What causes CRPS? This is where we begin to find incomplete answers. In most cases, the cause is either from trauma or after surgery, but sometimes there is no identifiable cause.1-3 The two cited types are CRPS 1 and CRPS 2, and the only difference between them is the cause. In CRPS 1, the cause is not fully known while CRPS 2 has a known cause of nerve injury. Other than this, both types of CRPS present with similar signs and symptoms.

Type 1 was formerly known as RSD and presented following some noxious event or cause of immobilization.4 Type 2 was formerly known as causalgia.4

In regard to nerves and pain, there are two basic groups of nerve fibers: myelinated and unmyelinated.2 Myelin is a sheath that wraps around the nerve and increases the speed of signal transmission. There are three types of fibers based on their thickness: thickest (Type A), medium (Type B) and thinnest (Type C). Type C fibers are unmyelinated, slow, and conduct dull pain signals. Pain transmits/refers by nociceptors.

Who is at risk for CRPS? The known risk of CRPS in children is low although one may consider it in preadolescent females, according to Harris and colleagues.3 Some may even argue that middle-aged women with a history of anxiety or depression are an increased risk, especially if they undergo foot surgery.3 Having said that, there is no true identifiable group that is more prone to developing CRPS.

A Closer Look At CRPS Signs And Symptoms

Patients will complain of electricity-like, burning pain or a deep, dull bone ache.1

A physical exam may reveal the following:
• Hyperalgesia (sharp prick with the broken wooden end of a cotton swab causes extreme pain that lasts longer than it should)2
• Allodynia (pressure or brushing with a cotton swab invokes pain)2
• Swelling
• Redness or blue mottled appearance (these changes depend on the vascular changes)
• Discrepancy in skin temperature between limbs
• Hyperhidrosis or hypohidrosis (depending on the stage)
• Decreased active joint range of motion (ROM) in comparison to the other limb (rapid movement of joints in the effected limb with be slower and have less control)2
• Shiny skin
• Nail changes (clubbing, brittleness)
• Muscle atrophy

Patients with CRPS may also have the “kickoff” position.5 This is a newly classified sign to hopefully aid in early diagnosis. Physicians have noticed that most patients with CRPS will hold the affected limb in an extended position while sitting on the exam table. Upon lowering the limb into a flexed position, the patient would unknowingly return the limb to the extended position when distracted. Patients feel this is a position of comfort. As therapy ensued and pain decreased, the degree of leg extension would also decrease. Physicians feel this sign can be a clinical correlation to successful therapy.

A study by Veldman in 1996 showed that discoloration of the skin occurred in 91 percent of patients, altered skin temperature in 92 percent, edema in 69 percent, and decreased ROM in 88 percent of patients.6 These numbers may vary depending on the source you read, but it gives you an idea of the complexity of the disorder. As mentioned previously, this is a diagnosis of exclusion. Many other pathological conditions may show similar signs and symptoms. The differential diagnosis includes:1

1. Compartment syndrome
2. Diabetic neuropathy
3. Fibromyalgia
4. Hysteria
5. Malingering
6. Lyme disease neuropathy
7. Tarsal tunnel syndrome

Pertinent Pearls On Diagnosing And Treating CRPS

Physical exam is the mainstay of diagnosis. X-rays and magnetic resonance images (MRI) help you exclude other possibilities and neither are pathognomonic.3 Some would argue that a three-phase Technetium bone scan aids in diagnosis. This test would show diffuse tracer uptake in the delayed phase (phase three).1 Some studies report a 96 percent sensitivity and 98 percent specificity of this test in diagnosing CRPS.1

There is no definitive treatment. To be honest, CRPS is as difficult to treat as it is to diagnose. Everyone reacts differently to the approved methods of treatment. The following are all treatment options for CRPS.1-2

• Physical therapy (the mainstay and initial line of treatment)
• Transcutaneous nerve stimulation
• Acupuncture
• Nerve blocks (pharmacological agents (opioids, antidepressants, systemic steroids, anticonvulsants, calcium channel blockers, topical pain creams and pain specialists)

By now, you have hopefully gained a little perspective and insight into what a person with CRPS may go through. There is so much involved with the diagnosis and treatment of CRPS that both patients and physicians are easily discouraged.

References
1. Coughlin MJ, Mann RA, Saltzman CL (eds.) In Surgery of the Foot and Ankle, eighth edition, volume 2. Mosby, St. Louis.
2. McGlamry ED, et al. Foot and Ankle Surgery, third edition, volume 2. Lippincott, Williams and Wilkins, Philadelphia, 2001.
3. Harris EJ, Schimka KE, Carlson RM. Complex regional pain syndrome of the pediatric lower extremity. J Am Podiatr Med Assoc. 2014; 102(2):99-104.
4. Rewhorn MJ, Leung AH, Gillespie A, et al. Incidence of complex regional pain syndrome after foot and ankle surgery. J Foot Ankle Surg. 2014; 53(3):256-8.
5. Trevino SG, Panchbhavi VK, Castro-Aragon O, et al. The “kick-off” position: a new sign for early diagnosis of complex regional pain syndrome in the leg. Foot Ankle Int. 2007; 28(1):92-95.
6. Veldman PH, Goris RJ. Multiple reflex sympathetic dystrophy. Which patients are at risk for developing a recurrence of reflex sympathetic dystrophy in the same or another limb? Pain 1996;64(3):463-6.

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