summary Complex Regional Pain Syndrome, also known as reflex sympathetic dystrophy, is an idiopathic condition caused by an aberrant inflammatory response that leads to sustained sympathetic activity in a perpetuated reflex arc. Patients present with extremity pain out of proportion to physical exam findings Diagnosis is made clinically with the Budapest diagnostic criteria and can be confirmed by pain relief with sympathetic block. Treatment is usually physical therapy, pain medication, nerve stimulation or nerve blockade. Surgical sympathectomy is indicated in cases of progressive pain that fails nonoperative management. Epidemiology Incidence US incidence is 5.5 per 100,000 person-years Demographics females more commonly affected (4:1) incidence increases with age up until 70 years old Anatomic location 60% occurs in the upper extremities 40% occurs in the lower extremities Risk factors trauma with an exagerrated response to injury most common reason for a poor outcome following a crush injury to the foot surgery prolonged immobilization anxiety or depression use of ACE inhibitors at the time of trauma history of migraines or asthma smoking fibromyalgia Etiology Pathophysiology aberrant inflammatory response vasomotor dysfunction maladaptive neuroplasticity Genetics thought to have a genetic predisposition siblings of young-onset CRPS patients have an increased risk of developing CRPS associated with polymorphisms in TNF-alpha and ACE genes Prevention vitamin C 500mg daily x 50 days in distal radius fractures treated conservatively 200mg daily x 50 days if impaired renal function vitamin C also has been shown to decrease the incidence of CRPS (type I) following foot and ankle surgery avoid tight dressings and prolonged immobilization Classification Lankford and Evans Stages of RSD Stage Onset Exam Imaging Acute 0-3 months Burning pain, redness, swelling, warmth, hyperhidrosis, hyperesthesia, cold intolerance, joint stiffness Normal x-rays, positive three-phase bone scan Subacute (dystrophic) 3-12 months Worsening pain, cyanosis, dry skin, stiffness, skin atrophy Subchondral osteopenia on x-ray Chronic (atrophic) > 12 months Diminished pain, glossy skin, fibrosis, joint contractures, loss of hair and nails Extreme osteopenia on x-ray International Association for the Study of Pain Classification International Association for the Study of Pain Classification Type I CRPS without demonstrable nerve damage Most common CRPS without demonstrable nerve damage Type II CRPS with evidence of identifiable nerve damage Minimal positive response with sympathetic blocks Presentation Cardinal signs exaggerated pain swelling stiffness skin discoloration Physical exam vasomotor disturbance trophic skin changes hyperhidrosis "flamingo gait" if the knee is involved equinovarus defomity if the ankle is involved Imaging Radiographs findings osteopenia affects the patella if the knee is involved soft tissue swelling subperiosteal bone resportion preservation of joint spaces Three-phase bone scan indications can help to rule out CRPS type I (has high negative predictive value) phases phase I (2 minutes) shows an extremity arteriogram phase II (5-10 minutes) shows cellulitis and synovial inflammation phase III (2-3 hours) shows bone images phase IV (24 hours) can differentiate osteomyelitis from adjacent cellulitis findings increased uptake in all phases phase III is most sensitive Thermography used to quantify temperature differences between the limbs questionable utility EMG/NCV may demonstrate slowing in known nerve distribution (e.g. slowing of median nerve conduction for CRPS type II in the forearm) Studies Diagnosis usually clinical but can be confirmed by pain relief with sympathetic block early diagnosis is critical for a successful outcome Budapest diagnostic criteria 1. Continuing pain that is disproportionate to any inciting event 2. Must report at least one symptom in three (clinical diagnostic criteria) or four (research diagnostic criteria) of the following categories: sensory: hyperesthesia or allodynia vasomotor: temperature asymmetry, skin colour changes, or skin colour asymmetry sudomotor/edema: edema, sweating changes, or sweating asymmetry motor/trophic: decreased range of motion, motor dysfunction (weakness, tremor, or dystonia), or trophic changes (hair, nails, or skin) 3. Must display at least one sign at time of diagnosis in two or more of the following categories: sensory: hyperalgesia (to pinprick) or allodynia (to light touch, deep somatic pressure, or joint movement) vasomotor: temperature asymmetry, skin colour changes or asymmetry sudomotor/edema: oedema, sweating changes, or sweating asymmetry motor/trophic: decreased range of motion, or motor dysfunction (weakness, tremor, or dystonia), or trophic changes (hair, nails, or skin) 4. No other diagnosis better explains the signs and symptoms Differential Soft tissue infection Malingering Psychiatric disease (e.g. Clenched Fist Syndrome) Neuropathic pain Chronic pain Raynaud disease Thoracic outlet syndrome Arterial insufficiency Erythromelalgia Treatment Nonoperative physical therapy and pharmacologic treatment indications first line of treatment nerve stimulation indications symptoms present mainly in the distribution of one major peripheral nerve nerve blockade indications failed initial nonoperative treatment chemical sympathectomy indications acts as another option when physical therapy and less aggressive nonoperative management fails Operative surgical sympathectomy indications failed nonoperative management (including chemical sympathectomy) surgical decompression indications CRPS type II with known nerve involvement (e.g. carpal tunnel release if median nerve involved) best success for CRPS is if you can find an associated nerve problem and treat it Techniques Physical therapy and pharmacologic treatment modalities gentle physiotherapy tactile discrimination training graded motor imagery sequential process consisting of laterality reconstruction, motor imagery, and mirror therapy medications NSAIDs alpha blockers (phenoxybenzamine, prazosin) beta blockers (propranolol) anti-depressants anti-convulsants calcium channel blockers GABA agonists (gabapentin) bisphosphonates anti-arrhythmics corticosteroids calcitonin Nerve stimulation programmable stimulators placed on affected nerves types transcutaneous electrical stimulation (TENS) peripheral nerve stimulation spinal cord stimulation Nerve blockade types sympathetic stellate ganglion (for upper extremity) lumbar spinal (for lower extremity) peripheral nerve neuraxial/epidural agents anesthetics (lidocaine or bupivicaine +/- epinephrine) sympatholytics (bretylium, guanethidine) Chemical sympathectomy types stellate ganglion (for upper extremity) lumbar spinal (for lower extremity) agents phenol alcohol Surgical sympathectomy ideal for patients who have had a response to sympathetic nerve blockade methods excision electrocautery Prognosis Typically responds poorly to conservative and surgical treatments Better prognosis if upper extremity, warm CRPS, children