Complex Regional Pain Syndrome
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Basics
Description
- Complex regional pain syndrome (CRPS) is a pain syndrome that can be chronic and debilitating. It is divided into two subtypes and can have significant physical and psychosocial short- and long-term disability. Most cases are a result of a physical insult to an extremity such as trauma or surgery.
- Type I: no nerve injury (reflex sympathetic dystrophy [RSD])
- Type II: associated with a demonstrable nerve injury (causalgia)
- Synonym(s): traumatic erythromelalgia; Weir Mitchell causalgia; causalgia; RSD; posttraumatic neuralgia; sympathetically maintained pain
Epidemiology
- Incidence of 5.46 to 26.2/100,000 for type I and 0.82/100,000 for type II in United States (1,2)
- Peak age 50 to 70 years
- Predominant gender: female > male (3:1, 60–81%), favoring postmenopausal
- Recent studies found 3.8% occurrence after wrist fracture and 7% occurrence after intra-articular ankle fracture—both independent strong risk for CRPS.
- More prevalent in patients that report higher than usual expected pain in early phases of trauma. Latency depends on normal injury recovery time—prolonged pain (greater than 2 months) after injury hints at diagnosis.
Etiology and Pathophysiology
- Poorly understood activation of abnormal sympathetic reflex that lowers pain threshold
- Increased excitability of nociceptive neurons in the spinal cord; “central sensitization”
- Exaggerated responses to normally nonpainful stimuli (hyperalgesia, allodynia)
- Type II is associated with physical injury to nerve.
- Emerging information reveals CNS changes (functional, anatomic, biochemical) in addition to spinal level changes. Increased levels of immunomodulators suggest autoimmune component.
Genetics
No known genetic pattern
Risk Factors
- Minor or severe trauma (upper extremity fracture-particularly distal radius noted in 44% of those with CPRS)
- Surgery (particularly carpal tunnel release)
- Lacerations
- Burns
- Frostbite
- Casting/immobilization after extremity injury
- Penetrating injury
- Polymyalgia rheumatica
- Myocardial infarction (MI)
- Cerebral vascular accident
General Prevention
- Early mobilization after fracture, stroke, and MI has proven benefit in reducing incidence of CRPS.
- One study of wrist fractures found that addition of 500 mg/day of vitamin C lowered rates of CRPS.
- There is evidence that limiting use of tourniquets, liberal regional anesthetic use, and ensuring adequate perioperative analgesia can reduce the incidence of CRPS-I.
Commonly Associated Conditions
- Serious injury to bone and soft tissue
- Herpes zoster
- Postherpetic neuralgia results from partial or complete damage to afferent nerve pathways.
- Pain occurs in dermatomes as a sequela of herpes zoster.
- Signal exists for patients having comorbid painful conditions or psychiatric diagnosis at increased risk of developing CPRS.
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Basics
Description
- Complex regional pain syndrome (CRPS) is a pain syndrome that can be chronic and debilitating. It is divided into two subtypes and can have significant physical and psychosocial short- and long-term disability. Most cases are a result of a physical insult to an extremity such as trauma or surgery.
- Type I: no nerve injury (reflex sympathetic dystrophy [RSD])
- Type II: associated with a demonstrable nerve injury (causalgia)
- Synonym(s): traumatic erythromelalgia; Weir Mitchell causalgia; causalgia; RSD; posttraumatic neuralgia; sympathetically maintained pain
Epidemiology
- Incidence of 5.46 to 26.2/100,000 for type I and 0.82/100,000 for type II in United States (1,2)
- Peak age 50 to 70 years
- Predominant gender: female > male (3:1, 60–81%), favoring postmenopausal
- Recent studies found 3.8% occurrence after wrist fracture and 7% occurrence after intra-articular ankle fracture—both independent strong risk for CRPS.
- More prevalent in patients that report higher than usual expected pain in early phases of trauma. Latency depends on normal injury recovery time—prolonged pain (greater than 2 months) after injury hints at diagnosis.
Etiology and Pathophysiology
- Poorly understood activation of abnormal sympathetic reflex that lowers pain threshold
- Increased excitability of nociceptive neurons in the spinal cord; “central sensitization”
- Exaggerated responses to normally nonpainful stimuli (hyperalgesia, allodynia)
- Type II is associated with physical injury to nerve.
- Emerging information reveals CNS changes (functional, anatomic, biochemical) in addition to spinal level changes. Increased levels of immunomodulators suggest autoimmune component.
Genetics
No known genetic pattern
Risk Factors
- Minor or severe trauma (upper extremity fracture-particularly distal radius noted in 44% of those with CPRS)
- Surgery (particularly carpal tunnel release)
- Lacerations
- Burns
- Frostbite
- Casting/immobilization after extremity injury
- Penetrating injury
- Polymyalgia rheumatica
- Myocardial infarction (MI)
- Cerebral vascular accident
General Prevention
- Early mobilization after fracture, stroke, and MI has proven benefit in reducing incidence of CRPS.
- One study of wrist fractures found that addition of 500 mg/day of vitamin C lowered rates of CRPS.
- There is evidence that limiting use of tourniquets, liberal regional anesthetic use, and ensuring adequate perioperative analgesia can reduce the incidence of CRPS-I.
Commonly Associated Conditions
- Serious injury to bone and soft tissue
- Herpes zoster
- Postherpetic neuralgia results from partial or complete damage to afferent nerve pathways.
- Pain occurs in dermatomes as a sequela of herpes zoster.
- Signal exists for patients having comorbid painful conditions or psychiatric diagnosis at increased risk of developing CPRS.
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