Complex Regional Pain Syndrome

Complex Regional Pain Syndrome (CRPS) is a rare, chronic pain disorder that is caused by sustaining trauma to the extremities. The symptoms include persistent weakness, inflammation, swelling, and excess sweating. The most curious symptom is extreme pain from a source that does not typically cause pain (or pain that is disproportionate from the injury), phenomena referred to as allodynia or hyperalgesia. It is an incurable disease that leaves many questions unanswered, as it is not very well understood despite it first being observed in patients dating back to the 16th century.

• 1500s – CRPS is first noted by a surgeon after bloodletting (an ancient practice of withdrawing blood from a person’s veins for therapeutic reasons)
• 1864 – CRPS is first mentioned in North America during the Civil War, when the aftermath of gunshot wounds caused extreme burning pain and shiny, reddened skin
• 1872 – The term causalgia is first coined to describe a neurological disorder that produces long-lasting, intense pain after an injury to a peripheral nerve (which is used to describe CRPS type II)
• 1994 – The International Association for the Study of Pain (IASP) developed the current name for CRPS
• 2003 – Budapest criteria for current CRPS diagnosis
• 2010 – CRPS Severity Score is created, which includes eight signs and eight symptoms that are looked for during history intake and a physical examination¹

The most notable symptom of CRPS is that its symptoms, in and of themselves, do not feel proportionate to the injury that triggered them. Oftentimes, no onset injury needs to occur for CRPS to develop. Symptoms can include:

• Persistent weakness
• Inflammation and swelling
• Edema
• Excessive sweating irrespective of heat or exercise (hyperhidrosis)
• Extreme pain disproportionate to the initial injury
• Skin color asymmetry
• Motor changes
• Decreased range of motion
• Life-long pain
• Psychological co-morbidities due to the pain’s persistence, such as isolation and depression²

CRPS usually first starts with the patient suffering an injury, although it is not a requirement that an injury precede the symptoms. According to the IASP criteria for CRPS, the disorder can be diagnosed when 2 to 4 of the following criteria are met:

1. The presence of a preceding event or injury (not necessary, however, because 5% to 10% of patients will have no such history)
2. Continuous pain which is disproportionate to the initial injury
3. Swelling or blood flow changes in the skin or sweat gland abnormalities
4. An absence of another condition that would otherwise explain the symptoms³

The Budapest criteria, created in 2003, set forth standards more specific to CRPS. According to its measures, patients must meet all four of the following criteria:⁴

1. Continuous pain disproportional to the inciting event
2. At least one symptom in three or more of the following categories –
   1. Sensory
   2. Vasomotor (temperature and skin color asymmetries)
   3. Submotor/edema (swelling and sweating changes)
   4. Motor/trophic (weakness, decreased range of motion, tremors etc)
3. At least one sign is present upon evaluation in two or more of the above categories
4. Absence of another diagnosis that would better explain the symptoms and signs

There are two major subtypes of CRPS – Type I and Type II – with a third subtype for cases that do not fully fit into either of the main two types:⁵

• Type I – occurs in the absence of major nerve injury
  • Accounts for the majority of CRPS cases
  • Follows a relatively minor trauma, such as a sprain, twist, dislocation, or soft tissue injury, or in some cases, no injury at all
  • Most common in populations under age 18⁶
• Type II – occurs in the presence of a major, identifiable nerve injury

There are two distinct phases of CRPS:

• The “warm” phase in the initial period of the disease which consists of:
  • “Classic” inflammation - pain, redness, heat, swelling, and loss of function
  • “Neurogenic” inflammation – activated by the peripheral nervous system; increased sensitivity in pain receptors
• The “cold phase” approximately six months after:
  • Changes in soft tissue and bones⁷

Other causes and exasperators include:

• The central nervous system changing the way the brain comprehends the state of the injured extremity
• Psychological stressors (patients with higher reported anxiety, self-reported pain scores, depression, or PTSD had worse symptoms)
  • These stressors have been attributed to an increase in the release of anxiety-related biomarkers that increase one’s perception of pain.

• There is no current treatment to cure CRPS. Treatment goals focus on pain reduction and increasing functionality.⁸
• Treatments include physical therapy, occupational therapy, cognitive behavioral therapy, neuropathic medications, and anti-inflammatories.⁹
• An experimental procedure, neuromodulation, has been promising, where portions of the spinal nerves are stimulated or blocked to reduce pain.
• Medications that slow bone loss (bisphosphonates) are also used.¹⁰
• Prognosis is highly variable and can range from mild to chronic persistence.
• CRPS is likely a chronic condition
• CRPS is more prevalent in females and in patients with psychiatric comorbidities

• Due to the variability in symptoms, most patients encounter a delay in diagnosis and treatment of CRPS.¹¹
• Failure to timely and properly diagnose CRPS may become a viable legal claim for a patient.