Reflex sympathetic dystrophy may occur in either the upper or lower limbs. The clinical course moves in stages:

• Stage 1: The patients develops pain with an identifiable cause (it may not be found or apparent). There is throbbing pain, abnormal sensations like burning and allodynia with localized edema. The distribution of the pain is not compatible with a nerve region. There will be vasomotor disturbances with changes in temperature and skin colour. There may be radiological changes but they are minimal at this stage.
• Stage 2: In this stage there is progression of soft tissue edema and skin thickening with associated muscle wasting. This occurs from 3 to 6 months after onset.
• Stage 3: The third stage is characterized by limitation of movement, with severe contractures and trophic skin. The radiograph shows significant demineralization [8].

• Burning Pain

  Reflex sympathetic dystrophy (RSD) is characterized mostly by: (burning) pain, restricted range of motion, oedema and autonomic disturbances. [ncbi.nlm.nih.gov]

  Patients may complain of burning pain for several months before the diagnosis is confirmed. [muirortho.com]

• Fever

  A 14-year-old girl with familial Mediterranean fever (FMF) had had acute attacks of fever, abdominal pain, and arthritis for 4 years. [ncbi.nlm.nih.gov]

  When at University, one of my professors, referring to fevers without cause or etiology (FUO), told us that fevers of unknown origin were ‘more unknown to some than to others’. [drpinal.com]

  Scintigraphy using labelled indium has demonstrated juxta-articular changes, but these seem to be pseudoinflammatory in nature. 19 Patients do not have a fever, and haematological and biochemical investigations and tests of immune function are normal. [jnnp.bmj.com]

• Lower Extremity Pain

  This disorder should be considered in any painful pelvic girdle syndrome or lower extremity pain. The hip is involved in 88% of cases. Symptoms develop in the third trimester of pregnancy, between the 26th and the 34th weeks. [ncbi.nlm.nih.gov]

• Abnormal Sweating

  Most CRPS features-spreading pain and skin hypersensitivity, vasomotor instability, osteopenia, edema, and abnormal sweating-are explicable by small-fiber dysfunction. [ncbi.nlm.nih.gov]

  The symptoms of Type II are similar to Type I and include changes in temperature near the site of the injury, abnormal sweating, and changes in blood flow, which affects skin coloration. [ddjlawtampa.com]

  There is pain and abnormal sensation in a certain area with abnormal sweating and swelling. Cause: The cause is unknown, but it is thought that inciting events such as trauma and surgery may be the cause. In many people no cause is found. [symptoma.com]

  Reflex Sympathetic Dystrophy (RSD) is a chronic pain disorder associated with sensitivity to light touch swelling, skin color and temperature changes, weakness, abnormal sweating, muscle atrophy, and subsequent depression. [bethesdahbot.com]

  He will then note if the continuing pain you are suffering is disproportionate to the injury suffered (if there was one) and will determine whether there is swelling or excessive accumulation of fluid in your tissues (edema) or abnormal sweat gland activity [disability-benefits-help.org]

• Palmar Hyperhidrosis

  We report the case of a 13-year-old girl that was seen for a painful swelling of the right hand associated with palmar hyperhidrosis, which occurred after a trauma to the hand. [ncbi.nlm.nih.gov]

• Leukonychia

  Unilateral leukonychia, Beau's lines, nailfold swelling, and nail clubbing have been an observed sequela of RSD. We present a case of a unilateral atypical trachyonychia occurring in the setting of RSD after traumatic fracture of a digit. [ncbi.nlm.nih.gov]

• Arthralgia

  […] for 3/12 in four or more joints Minor criteria Current/historic Brighton score of 1, 2 or 3/9 (0, 1, 2, 3/9 if 50 years old) Arthralgia for minimum of 3 months in 1–3 joints, or back pain for minimum of 3 months, or spondylosis/spondylolysis/spondylolisthesis [medical-dictionary.thefreedictionary.com]

• Swelling of Hand

  (Photo provided by Jenny Loder) One symptom of RSD is swelling of hands and feet. Shown is Jenny Loder's left hand during an RSD flair up. When Jenny Loder had surgery five years ago, she didn't realize how much it would change her life. [nj.com]

• Joint Deformity

  Surgery should be considered before there is significant joint deformity. Chemical sympathectomy with alcohol has also been done. [symptoma.com]

• Oligoarthritis

  Spondyloarthropathy was diagnosed based on oligoarthritis with sacroiliitis, presence of HLA B27, and a favorable response to non-steroidal antiinflammatory therapy. [ncbi.nlm.nih.gov]

• Neuralgia

  We propose that persistent RSD/CRPS-I is a post-traumatic neuralgia associated with distal degeneration of small-diameter peripheral axons. [ncbi.nlm.nih.gov]

  Noradrenaline-evoked pain in neuralgia. Pain. 1995; 63:11-20. [10] Maihofner CM, Handwerker HOM, Neundorfer BM, et al.: Patterns of cortical reorganization in complex regional pain syndrome. [ainsworthinstitute.com]

  In addition to causalgia, RSD is also known as Sudeck's atrophy, post-traumatic neuralgia, and shoulder-hand syndrome. All of these names are used interchangeably, adding to the confusion in diagnosing and treating RSD. [amputee-coalition.org]

  […] and other Cranial Neuralgias (3 Viewing) For discussion of Occipital Neuralgia, Glossopharyngeal Neuralgia, Nervus Intermedius (or Geniculate Neuralgia), and Vegal and Superior Laryngeal Neuralgia. [neurotalk.psychcentral.com]

• Hyperesthesia

  Reflex sympathetic dystrophy is characterized by constant burning pain and hyperesthesia in an extremity. Lower extremities are usually affected. Pain is accompanied by swelling, sweating, vasomotor instability and sometimes trophic changes. [ncbi.nlm.nih.gov]

  Case Reports First Online: 01 April 1992 Abstract We describe a 9 1/2 year old girl who suffered from severe recurrent pain and functional limitation in her right leg with hyperesthesia, hyperalgesia, color change and edema as the presenting symptoms, [link.springer.com]

  Typical symptoms of the disease are: Burning pain Edemas Hyperhidrosis Increased or decreased skin temperature Hyperesthesia Allodynia Restriction of movement Skin changes (livid complexion, dry skin, seborrheic skin) Altered hair and nail growth Advanced [flexikon.doccheck.com]

  Orthopedic Rehabilitation services Pain profilePAIN QUALIFIERS JOINT PAIN Aching 0 no pain Burning 1 mild pain with deep palpation Cramping Heaviness/fatigue 2 severe pain with deep palpation Numbness 3 severe pain with mild palpation Sharp/stabbing 4 hyperesthesia [slideshare.net]

• Peripheral Neuropathy

  Kim SH, Chung JM: An experimental model for peripheral neuropathy produced by segmental spine nerve ligation in the rat. Pain 1992, 50 :335–363. Google Scholar 27. [link.springer.com]

  neuropathy, but particularly various musculoskeletal disorders, may be misdiagnosed as RSD (see Schott 4 ). [jnnp.bmj.com]

  […] conditions: Bony or soft tissue injury Peripheral neuropathy, nerve lesions Arthritis Infection Compartment syndrome Arterial insufficiency Raynaud’s Disease Lymphatic or venous obstruction Thoracic Outlet Syndrome (TOS) Gardner-Diamond Syndrome Erythromelalgia [physio-pedia.com]

  Neurologic conditions, such as diabetic and small-fiber peripheral neuropathies, entrapment neuropathies, thoracic outlet syndrome, and discogenic disease, should be excluded. [anesthesiology.pubs.asahq.org]

• Complex Regional Pain Syndrome Type II

  Review Topic QID: 4811 2 Complex Regional Pain Syndrome, type II 4 Complex Regional Pain Syndrome, type I ML 2 Select Answer to see Preferred Response PREFERRED RESPONSE 4 (OBQ04.43) A 34-year-old laborer has her left foot crushed in a piece of farming [orthobullets.com]

  Geniculate neuralgia... by kiwi33 01-10-2019 04:22 PM 168 1,070 Reflex Sympathetic Dystrophy (RSD and CRPS) (24 Viewing) Reflex Sympathetic Dystrophy (Complex Regional Pain Syndromes Type I) and Causalgia (Complex Regional Pain Syndromes Type II)(RSD [neurotalk.psychcentral.com]

  Transcutaneous Electrical Nerve Stimulation for the Management of Neuropathic Pain: The Effects of Frequency and Electrode Position on Prevention of Allodynia in a Rat Model of Complex Regional Pain Syndrome Type II. Phys Ther 2006;86:698-709. [physio-pedia.com]

There is no useful laboratory testing in this syndrome. Majority of the diagnosis will come from the history and physical exam. Plain radiographs will show pronounced demineralization of the skeleton affected by the pain and edema. This worsens as the disease progresses.

Bone radionuclide test may be useful in early disease, but findings are not specific for this condition. Magnetic resonance imaging (MRI) may be useful in identifying patients, as it gives useful information on the soft tissue and skin changes. CT scans may show multiple focal areas of osteoporosis.

Autonomic testing like resting skin temperature and resting sweat output may be done to document the vasomotor symptoms. An increased resting skin temperature is highly suggestive of this disease [9].

• Abnormal Bone Scan

  A combination of normal radiographs, a normal leukocyte study, and an abnormal bone scan in the region of tenderness and swelling excluded other possibilities and suggested RSD. [ncbi.nlm.nih.gov]

There are two major therapies being used currently. There is insufficient data on other effective therapies and little randomized control studies.

• Sympathetic blocks: A local anesthetic such as lidocaine or bupivacaine is injected into the stellate and upper dorsal sympathetic ganglia to block the efferent nerves. There should be a Horner's syndrome induced after this, which will disappear soon after (30 mins). The patient then undergoes intensive physiotherapy and occupational therapy. The patient may require 1 to 2 blocks per week until the condition is treated. For lower limbs a lumbar block is used [11].
• Sympatholytic drugs in early disease may be effective. Regional infusions are usually effective [12] [13].

Other treatments such as non steroidal anti-inflammatory drugs (NSAIDs) may be used. Corticosteroids are highly effective in reducing pain and allowing for physical therapy. Surgical methods may be used and include thoracic or lumber sympathectomy. This is indicated in cases resistant to therapy. Surgery should be considered before there is significant joint deformity. Chemical sympathectomy with alcohol has also been done.

The course of the disease is variable, but if caught early and treated appropriately, many patients do not progress on to the later stages of the disease. There is little data on mortality, but morbidity may be significant.

Reflex sympathetic dystrophy usually occurs after injury, which can be traumatic or postsurgical. In some cases there may be no identifiable incident. In some patients an event such as myocardial ischemia or a hemiplegic stroke, may be the inciting event. Common surgical procedures such as arthroscopy of the knee and other joints may be the cause in some patients. There also have been cases in diseases such as pancreatic and pancoast tumors [2] [3].

35% of patients have no identifiable inciting event. There is an estimated 5% prevalence in people with a previous upper extremity injury. The syndrome was prevalent (12%) in patients with hemiplegic stroke, but this has significantly decreased with the advent of early mobilization. There is no gender or race predilection, but it has a peak incidence between 30 to 60 years [4].

There appears to be a need of three conditions to be present for reflex sympathetic dystrophy to occur:

• Abnormal sympathetic reflex
• Persistent painful lesion 
• Predisposition 

The true mechanism of this complex regional pain syndrome is unclear, but appears to involve the formation of a new reflex arc after the inciting event. The arc follows a sympathetic pathway and is then modulated by cortical centres and produces vascular changes. The pain occurs possibly due to the triggering event causing nerve damage with increased sensitivity to sympathetic neurotransmitters such as epinephrine.

There is thought to be prolonged and constant release of pain inciting peptides from peripheral nerves causing nerve inflammation with subsequent pain and allodynia. Neuropeptide Y and substance P have been implicated in this. There appears to be a genetic predisposition. A few human leukocyte antigen (HLA) associations have been found, a few examples include HAL-A3, and DR2 [5] [6].

Quick physiotherapy and mobilization has been noted to reduce the incidence, especially in patient with hemiplegic strokes. Early mobilization is advised when possible after any intervention or injury of limb, to reduce the occurrence of this disease.

There are two types of a complex regional pain syndrome (CRPS):

• Type 1, when the complex regional pain syndrome is not caused by an identifiable nerve lesion. Names include reflex sympathetic dystrophy, Sudeck's atrophy and reflex neurovascular dystrophy.
• Type 2, when there is an identifiable lesion. It was previously known as causalgia [1]. 

Both types are chronic systemic diseases characterized by severe pain, swelling, and vasomotor dysfunction.

• Definition: Reflex sympathetic dystrophy is a disease whereby there is a problem with a certain area of your body, usually a hand or leg. There is pain and abnormal sensation in a certain area with abnormal sweating and swelling. 
• Cause: The cause is unknown, but it is thought that inciting events such as trauma and surgery may be the cause. In many people no cause is found. The triggering event causes there to be abnormal sensation in the affected area. 
• Symptoms: The most common symptom is pain which can be burning or tingling. Some complain of throbbing pain which can also be severe. The affected area is sensitive to touch or cold, there is swelling and the skin become thick and rough. The muscles in the area become weak and smaller.
• Diagnosis: Most of the diagnosis is made from asking you questions and examining you. They skin temperature and the amount of sweat in the area will be recorded. 
• Treatment: The treatment involves blocking the nerves and physical therapy. You may also be given drugs to help with the pain and swelling.
• Prevention: Quick physical therapy after an injury or stroke is advised to reduce the occurrence of the disease.

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11. Cepeda MS, Carr DB, Lau J. Local anesthetic sympathetic blockade for complex regional pain syndrome. Cochrane Database Syst Rev 2005
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13. Olcott C 4th, Eltherington LG, Wilcosky BR, et al. Reflex sympathetic dystrophy--the surgeon's role in management. J Vasc Surg 1991; 14:488.