ABSTRACT
Complex regional pain syndrome, type I (CRPS I) (formerly known as reflex sympathetic dystrophy, RSD) and complex regional pain syndrome, type II (CRPS II) (formerly known as causalgia) are symptom complexes that evoke a great deal of confusion. Very often, physicians do not recognize that these are separate and distinct entities, and commonly assume that they are disorders of the same etiology, as well as responsive to the same treatment. Clinically, this has not proven accurate. CRPS I is a group of symptoms and clinical signs that usually follows a minor injury to a limb. In contradistinction, CRPS II is usually associated with peripheral nerve injury, classically from a bullet wound or some other partial nerve damage. Throughout this chapter, for the sake of consistency, earlier references that used the terms of RSD are referenced or quoted as CRPS I, despite the original nomenclature. This same approach is used for references using the term causalgia, which are changed, for the sake of continuity, to CRPS II. In a very fine review article, Payne (1986) clearly defined the distinction between CRPS I and CRPS II, although at the time he called them RSD and causalgia, respectively. This has been further expanded by the International Association for the Study of Pain in a supplement edited by Merskey (1986; Table 36.1). A further expansion of this comparison is offered by Baron, Blumberg, and Janig (1996; Table 36.2). Comparison between CRPS Type I and Type II
Complex Regional Pain Syndrome, Type II (Causalgia)
Definition
Burning pain, allodynia, and hyperpathia, usually in the hand or foot, after a partial injury to a nerve or one of its major branches
Site
In the region of the limb innervated by the damaged nerve, not around the entire limb
Main features
Onset usually immediately after partial nerve injury or may be delayed for months; CRPS II of the radial nerve very rare; the nerves most commonly involved are the median, the sciatic, and tibial, and the ulnar; spontaneous pain; pain described as constant, burning, exacerbated by light touch, stress, temperature change or movement of involved limb, visual and auditory stimuli (e.g., a sudden sound or bright light, emotional disturbances)
Associated symptoms
Atrophy of skin appendages, secondary atrophic changes in bones, joints, and muscles Cool, reddish, clammy skin with excessive sweating; sensory and motor loss in structure innervated by damaged portion of nerve
Signs
Cool, reddish, clammy, sweaty skin with atrophy of skin appendages and deep structures in painful area
Laboratory findings
Galvanic skin; responses and plethysmography revealing signs of sympathetic nervous system hyperactivity, roentgenograms possibly showing atrophy of bone
Usual course
If untreated, the majority of patients having symptoms that persist indefinitely; spontaneous remission occurring
Relief
In early stages of CRPS II (first few months), sympathetic blockade plus vigorous physical therapy usually providing transient relief; repeated blocks usually leading to long-term relief; when a series of sympathetic blocks not providing long-term relief, sympathectomy indicated; long-term persistence of symptoms reducing the likelihood of successful therapy
Social and physical disabilities
Disuse atrophy of involved limb; complete disruption of normal daily activities by severe pain; risk of suicide, drug abuse if untreated
Pathology
Partial injury to major peripheral nerve; actual cause of pain unknown; peripheral central and sympathetic mechanisms involved in an unexplained way
Essential features
Burning pain and cutaneous hypersensitivity with signs of sympathetic hyperactivity in portion of limb innervated by partially injured nerve
Complex Regional Pain Syndrome, Type I (Reflex Sympathetic Dystrophy)
Definition
Continuous pain in a portion of an extremity after trauma that may include fracture but does not involve a major nerve, associated with sympathetic hyperactivity
Site
Usually the distal extremity adjacent to a traumatized area; all around the limb
System
Peripheral nervous system; possibly the central nervous system
Main features
The pain follows trauma (usually mild), not associated with significant nerve injury; the pain described as burning, continuous, exacerbated by movement, cutaneous stimulation, or stress; onset usually weeks after injury
Associated symptoms
Initially vasodilatation with increasing temperature, hyperhidrosis, edema, and reduced sympathetic activity also occurring; atrophy of skin, vasoconstriction, and appendages; cool, red, clammy skin variably present; disuse atrophy of deep structures possibly progressing to Sudeck’s atrophy of bone; aggravated by use of body part, relieved by immobilization; sometimes follows a herniated intervertebral disc, spinal anesthesia, poliomyelitis, severe iliofemoral thrombosis, or cardiac infarction; may appear as the shoulder-hand syndrome; later vasospastic symptoms becoming prominent with persistent coldness of the affected extremity, pallor or cyanosis, Raynaud’s phenomenon, atrophy of the skin and nails, and loss of hair, atrophy of soft tissues and stiffness of joints; without therapy these symptoms possibly persisting; not necessary for one patient to exhibit all symptoms together; an additional limb or limbs possibly affected as well
Signs
Variable; may be florid sympathetic hyperactivity
Laboratory findings
In advanced cases, radiographs possibly showing atrophy of bone, and bone scan changes over time
Usual course
Persists indefinitely if untreated; small incidence of spontaneous remission
Relief
Sympathetic block and physical therapy; sympathectomy if long-term results not achieved with repeated blocks; may respond in early phases to high doses of corticosteroids (e.g., prednisone, 50 mg daily)
Complications
Disuse atrophy of involved limb; risk of suicide and drug abuse if untreated; sometimes spreads to contralateral limb
Social and physical disabilities
Depression, inability to perform daily activities
CRPS I
CRPS II
Pathology
Unknown
Partial nerve lesion
Essential features
Burning pain in distal extremity usually after minor injury without nerve damage
Nerve damage
Differential diagnosis
Unrecognized local pathology (fracture, strain, sprain)
Post-traumatic vasospasm, nerve entrapment syndromes radiculopathies, or thrombosis
Criteria for Differential Diagnosis of CRPS Types I and IICRPS I
CRPS II
Etiology
Any kind of lesion
Partial nerve lesion
Localization
Distal part of extremity, or entire limb;
Any peripheral site of body; mostly confined to territory of affected nerve Rare
Spreading of symptoms
Obligatory
Rare
Spontaneous pain
Common, mostly deep and superficial orthostatic component
Obligatory, predominately superficial, no orthostatic component
Mechanical allodynia
Most of patients with spreading tendency
Obligatory in nerve territory
Autonomic symptoms
Distally generalized with spreading tendency
Related to nerve lesion
Motor symptoms
Distally generalized
Related to nerve lesion
Sensory symptoms
Distally generalized
Related to nerve lesion
Note: From “Classification of Chronic Pain,” edited by H. Merskey and the Subcommittee on Taxonomy, 1986, Pain, 3(Suppl), pp. 28–29. Reprinted with permission.