Definition 

Complex regional pain syndrome is a chronic neuroinflammatory disorder usually affecting 1 or more extremities, characterized by continued regional pain disproportionate in time or degree to the usual course of any known trauma or lesion.

 Usually, has a distal predominance of abnormal sensory, motor, sudomotor, or  vasomotor edema, and/or trophic findings .

Classification 

- By     type   

Complex regional pain syndrome, type I (previously called reflex sympathetic dystrophy): patients without confirmed nerve injury  

Complex  regional pain syndrome, type II (previously called causalgia): patients with confirmed nerve injury  

- By     stage    

Stage 1 (lasts 1-3 months) :   Changes in skin temperature, alternating between warm and cold, Rapid growth of nails and hair. Muscle spasms and joint pain. Severe burning, aching pain that worsens with slight touch or breeze. Skin slowly becomes: Blotchy, purple, pale, or red Thin and shiny, Moist with sweat.       

Stage 2 (lasts 3-6 months) : Continued  changes in skin temperature and colour. Nails become cracked and break more easily. Slower hair growth,  Worsening pain, Stiff joints and weak muscles.  

 Stage 3 (irreversible changes)  Limited movement in limb due to contracture. Muscle wasting, Pain       throughout the entire limb.   

Clear history of trauma in most cases; 10% of patients     cannot recall any precipitating event. 

Most  common precipitating events : Fracture /Sprain /Surgery.  

Less common precipitating events: Injection/ Local infection / Burn / Frostbite 

Key symptom is prolonged pain that may be constant and severe   Onset      often occurs within a few days to a month but may be immediate in some cases

Pain may be described as burning, stabbing, dragging, pressing, throbbing, or constricting  Augmentation  of pain may occur during nonpainful touch, physical effort, heat, cold, or agitation   Positive sensory abnormalities   Spontaneous      pain: Allodynia /Hyperesthesia   Hyperalgesia      : Mechanical/Thermal/ Deep somatic  Vascular     abnormalities: Vasodilation/ Vasoconstriction /Skin temperature asymmetry/     Skin color changes (blue, red, purple, blotchy, or pale; skin may appear     shiny or thin)  Edema and sweating abnormalities:  Swelling     in the affected area / Hyperhidrosis  Motor     or trophic changes: Abnormal hair or nail growth (unusually slow or fast     growth patterns; brittle or grooved nails) / Tremor / Skin atrophy / Joint     stiffness  

Diagnosis

Clinical Evaluation 

Imaging Imaging     has low predictive value and is not routinely recommended 

- MRI is unable to reliably differentiate between normal posttraumatic changes and changes due to complex regional pain syndrome 

 - Plain radiographs of the affected area may show osteopenia or fracture but no      other specific findings   

- Triple-phase bone scans (3-phase bone scintigraphy) can be helpful for patients in early stages to exclude other pain syndrome diagnoses, but test sensitivity is low.

Findings may show bone defects (eg, hyperperfusion) that are consistent with complex regional pain syndrome; however, absence of these findings does not exclude this diagnosis.

Functional testing:  Nerve conduction study/electromyography: To rule out nerve injuries. 

Differential Diagnosis

1.   Deep vein thrombosis and thrombophlebitis

2.  Peripheral neuropathy 

3.  Diabetic neuropathy

 4. Infections: Herpes Zoster/ Lyme Disease

 5. Autoimmune disorders: Rheumatoid/ reactive arthritis

 6.  Thoracic Outlet syndrome  

Treatment

Goals 

Regain normal limb function by:  

Controlling edema  

Restoring  range of motion 

Improving tolerance for stress-loading activities and exercise  

Maximizing functional use  

Improve circulation

Reduce and relieve pain 

Improve pain coping skills 

Strategies for selecting pharmacotherapy include the following:

For patients with mild to moderate pain: prescribe simple analgesics

For patients with excruciating pain: prescribe opioids or sympathetic nerve blocks  

For patients with inflammation/swelling and edema: prescribe NSAIDs, steroids, or immune modulators  

For patients with depression, anxiety, or insomnia: prescribe sedatives or analgesic   antidepressants/anxiolytics  

For  patients with allodynia/hyperalgesia: prescribe anticonvulsants

For patients with osteopenia, immobility, and trophic changes: prescribe calcitonin or bisphosphonates

For patients with vasomotor disturbances: prescribe calcium channel blockers, sympatholytics, or sympathetic nerve blocks.  

Non Pharmacological treatment: Psychotherapy, Physiotherapy and occupational therapy. 

Summary  

Complex  regional pain syndrome is a chronic neuroinflammatory disorder usually affecting 1 or more extremities, characterized by continued regional pain 

Soft tissue injuries or fractures, especially of the wrist or ankle, are common  triggering events 

Pain of greater severity than expected in injury healing phase is indicative and often first-noticed symptom 

Clinical presentation is characterized by pain and tenderness of a distal extremity, usually accompanied by bone demineralization, trophic skin changes, and vasomotor instability

Diagnosis based largely on patient history and clinical findings, and may be assisted by utilizing the Budapest Consensus Group diagnostic criteria 1 A multidisciplinary management approach is most effective, including pain specialists, physical medicine and rehabilitation, neurology, anesthesiology, psychiatry/psychology, and neurosurgery

 Treatment is centred on physical therapy and pain management strategies 

Most patients with complex regional pain syndrome improve with a combination of medication and physical therapy; sympathectomy may be required in those whose symptoms are refractory to standard therapies 

Recovery may be affected by secondary psychological effects of chronic pain, such as depression or anxiety 

Early, aggressive treatment of pain may prevent chronic disease and later complications

Symptoms are variable and complex, and the timing of their onset after injury is variable, all of which complicate successful identification and treatment  

No known cause; treatment is subject to a trial approach  

Psychological features are important components to identify and aggressively treat; however, solely treating psychiatric aspects will lead to treatment      failure  Despite      treatment, chronic pain and long-term disability may result .