Causalgia

Causalgia is an old term that is now called complex regional pain syndrome type 2, is a neuropathic pain disorder in which pain, that occurs in the setting of known nerve trauma that is disproportionately far more painful than the degree of tissue injury and persists beyond the normal expected time for tissue healing ¹. Complex regional pain syndrome type 1, formerly known as reflex sympathetic dystrophy occurs in the absence of nerve trauma. Clinically they are indistinguishable and follow a regional rather than a dermatomal or peripheral nerve distribution and favor the distal extremities, though spread outside of the initially affected area commonly occurs to the proximal or contralateral limb. Complex regional pain syndrome is further subdivided into “warm” versus “cold,” and sympathetically-maintained (SMP) versus sympathetically-independent (SIP), which may affect prognosis and treatment options ².

Complex regional pain syndrome occurs in two types, with similar signs and symptoms, but different causes:

1. Complex regional pain syndrome type 1. Also known as reflex sympathetic dystrophy (RSD), this type occurs after an illness or injury that didn’t directly damage the nerves in your affected limb. About 90% of people with complex regional pain syndrome have type 1.
2. Complex regional pain syndrome type 2. Once referred to as causalgia, this type has symptoms similar to those of type 1. But type 2 complex regional pain syndrome occurs after a distinct nerve injury.

Complex regional pain syndrome usually develops after an injury, surgery, stroke or heart attack ³. The key symptom of complex regional pain syndrome is continuous, intense pain that is out of proportion to the severity of the injury, usually in your arm, leg, hand or foot. The pain gets worse over time. complex regional pain syndrome most often affects one of the arms, legs, hands, or feet, and the pain often spreads throughout the entire affected arm or leg ⁴. Other signs and symptoms may include ³:

• sensitivity to touch or cold
• swelling of the painful area
• changes in skin temperature (alternating between sweaty and cold), color (ranging from white and blotchy to red or blue) and/or texture, which may become tender, thin or shiny in the affected area
• joint stiffness and swelling
• muscle weakness, tremors, and/or muscle spasms
• changes in hair and nail growth
• decreased ability to move the affected body part.

Symptoms may change over time and vary from person to person. In some people, signs and symptoms of go away on their own. In others, symptoms can persist for months to years ³.

Causalgia pathophysiology is multifactorial and involves pain dysregulation in both the sympathetic and central nervous systems, with likely genetic, inflammatory and psychological contributions. An example of this would be light touching of the skin, which normally is not painful, yet it causes extreme pain perception in complex regional pain syndrome patients. The disproportionate pain is also reflected in normally painful stimuli, such as a pinprick, hurting more than it should (hyperalgesia). complex regional pain syndrome usually affects one limb after a limb injury or surgery. Usually patients with complex regional pain syndrome will experience limited use of their affected limbs due to the pain. Besides increased perception of pain, other signs and symptoms that are seen with complex regional pain syndrome particularly in its early stages are a warm, red, and swollen extremity on the affected side.

There is no cure for complex regional pain syndrome and no drug has been approved specifically for the disorder. Treatments are aimed at relieving painful symptoms. Complex regional pain syndrome is often treated with physical and occupational therapy. Doctors may prescribe topical analgesics, antidepressants, corticosteroids, and opioids to relieve pain, but no single drug or combination of drugs has produced consistent long-lasting improvement in symptoms. Other treatments may include nerve blocks, spinal cord stimulation and other types of neurostimulation, and surgery.

Causalgia causes

The exact cause of complex regional pain syndrome is unclear, but it is likely that there are multiple factors that contribute to its development.

Complex regional pain syndrome occurs as a result of varying degrees or types of tissue trauma but has even been documented in the absence of injury or due to periods of prolonged immobilization. The most common injury associated with developing complex regional pain syndrome is a fracture which occurs in > 40% of complex regional pain syndrome cases. Other common inciting injuries or insults include sprains, contusions, crush injuries, and surgery. Complex regional pain syndrome even has been reported to arise after seemingly innocuous interventions such as intravenous line placement. Increased psychological distress experienced during the physical injury associated with the onset of complex regional pain syndrome may affect its severity and prognosis.

Immobilization (e.g., casting) to keep a limb from moving in order to allow it heal is a common treatment for injuries such as broken bones, or fractures in the limb. In adults and pediatrics patients, complex regional pain syndrome type I was commonly seen in those who have a history of immobilization, and this was associated with a worsening of symptoms. Immobilization of limbs in patients after fractures or surgery results in an increase in sensitivity to pain, edema, and temperature increase in the affected limb. This suggests that immobilization may play a role in the development of the disease.

complex regional pain syndrome may also be caused in part by alterations to the nervous system of the body. One part of the nervous system is the sympathetic nervous system. The sympathetic nervous system is activated in “fight or flight” situations, which are times when the body is in high level of stress and requires alertness. During times of stress, the sympathetic nervous system constricts blood vessels to reduce blood flow to the extremities. In contrast, low sympathetic nervous system activity increases blood flow to the extremities. In complex regional pain syndrome, sympathetic function may initially be decreased, which could contribute to warm, red and swollen limbs. The sympathetic nervous system may also play a role in contributing to the pain associated with complex regional pain syndrome. Although it is believed that the sympathetic nervous system in complex regional pain syndrome may become linked to pain receptors, it is still unclear exactly how the sympathetic nervous system causes pain in patients with complex regional pain syndrome.

Inflammation may also play a significant role in the development of the syndrome. In complex regional pain syndrome, particularly in its early stages, it is found that patients have increased levels of inflammation-causing substances (cytokines) released by the body. Along with the inflammatory cytokines, there are pain-enhancing substances in the nerves that are released. The increased inflammatory and pain-producing substances in complex regional pain syndrome are a possible explanation for why a person with complex regional pain syndrome may experience pain from a stimulus that normally should not cause pain.

It is possible that genetic factors may contribute to complex regional pain syndrome; however, there is no clear genetic risk pattern known at this time. There are a few genes that may contribute to complex regional pain syndrome, but the ones most frequently identified are in genes that influence the immune system and inflammation. It is possible that particular genetic patterns a person is born with might increase the risk of developing complex regional pain syndrome after injury, but there is no evidence that complex regional pain syndrome is a disease that can be caused by genetic factors alone.

Psychological factors, such as anxiety, depression, and anger, may worsen the symptoms of complex regional pain syndrome. In children, psychological issues are often assumed to play a greater role in complex regional pain syndrome than in adults, but this belief remains unproven.

Causalgia pathophysiology

Complex regional pain syndrome results from damage to C-fibers and A-delta fibers that innervate soft tissue and bone in the great majority of instances ⁵. Complex regional pain syndrome may also occur after direct nerve injury and in approximately 10% of patients after damage in central nervous system pathways (stroke, head and spinal cord trauma, and multiple sclerosis).

Nociceptive pain occurs from potential or tissue destructive stimuli. It is mediated by high threshold unmyelinated C-fibers or thinly myelinated A-delta fibers whose primary neurons reside in the dorsal root ganglion ⁶. As pain is signalled through specific afferent nociceptive pathways, direct projections of these fibers activate ⁷:

1. the discriminative pain system (location, intensity and quality of stimulus);
2. the affective system (the unpleasantness of the stimulus);
3. the autonomic nervous system (sympathetics);
4. the motor system (nocifensor reflexes); and
5. the immune system.

Approximately 50% of patients have been casted and complex regional pain syndrome is rarely seen following complete nerve transection ⁸. Harden and Bruehl ⁹ applied factor analysis to 123 patients with complex regional pain syndrome who met International Association for the Study of Pain Criteria (IASP) and determined that signs and symptoms cluster into four distinct subgroups:

1. abnormalities in pain processing (allodynia, hyperalgesia and hyperpathia);
2. skin color and temperature changes (differential blood flow);
3. edema (neurogenic), vasomotor and sudomotor dysregulation; and
4. a motor syndrome.

Patients with complex regional pain syndrome have both enhanced and decreased sensation in areas of injury ¹⁰. These sensory abnormalities are a reflection of activity-dependent neuroplasticity and are similar to long term potentiation—an increase in synaptic efficacy and long term depression (long term depression) in which an afferent barrage is less effective in depolarizing a post synaptic neuron. These processes have been demonstrated in nociceptive neurons of pain models and are clinically relevant in patients ¹¹. Post synaptic Ca2+ influx through the N-methyl-D-aspartic acid (NMDA) receptor of pain transition neurons is critical for long term potentiation induction after removal of its Mg2+ block by high frequency firing of mechano-heat insensitive C-fibers (i.e., the injury barrage). Blockade of the N-methyl-D-aspartic acid receptor with ketamine has cured severe longstanding complex regional pain syndrome patients ¹².

A major mechanism underlying long term potentiation and long term depression is the number, position, type and conductance of AMPA (A-amino-3hy-droxy-5methly-4isoxazolepropionate) re-ceptors at the post synaptic density which opposes the afferent nociceptive axon. The induction and maintenance of long term potentiation or long term depression is dependent on the source (N-methyl-D-aspartic acid receptor; endoplasmic reticulum or voltage gated calcium channel) of the calcium concentration increase in the pain transition neurons ¹³. The greater the number of synaptic AMPA receptors, the more effective the transmission of the nociceptive barrage. Extra synaptic dispersal and internalization of AMPA receptors decreases synaptic transmission and causes long term depression ¹⁴. Long term potentiation and long term depression also are modified by increased transmitter release, dendritic, neuronal and post synaptic density structural alterations, activation of metabotropic glutamatergic receptors and nonspecific voltage-dependent cation complexes ¹⁵.

A high frequency afferent barrage generated by mechano-heat insensitive C fibers, and maintained by sensitized peripheral nociceptors or unresolved nerve pathology, co-releases the neuroactive peptides substance P and calcitonin gene related peptide (CGRP). This causes temporal summation in dorsal horn nociceptive neurons that releases the Mg2+ block of the glutamatergic N-methyl-D-aspartic acid receptor. The subsequent increase of Ca2+ concentration activates multiple enzymatic cascades (CaMKII, serine and threonine kinases, phosphatases) which, if prolonged, in-duces the transcription of new proteins, ion channels, receptors and induces novel genes ¹⁶. Chronic pain results in structural change of the pain matrix. A dynamic interplay between the site of injury and dorsal root ganglion primary neurons is maintained by orthograde and retrograde axonal transport. Growth factors derived from immune cells at the site of injury modulate peripheral and central N-methyl-D-aspartic acid receptors, G-protein coupled receptors, synaptic transmitters and modulators, while new sodium channels are upregulated on primary nociceptive afferents in the dorsal root ganglion and damaged nociceptive afferents ⁷.

Intrinsic plasticity, the probability that a post-synaptic neuron will be depolarized by a presynaptic input, is dependent on changes in the synthesis, insertion, density and functional properties of voltage-gated ion channels. Intrinsic plasticity of the pain transition neurons determines dendritic excitability and signal integration at the soma (i.e., its propensity to depolarize) ¹⁷. These changes of excitability lend to plasticity of the firing mode of the pain transition neurons whereby a normally firing neuron is converted into a burst firing neuron that, when depolarized, fires a high frequency all or non-burst of action potentials. This plasticity of firing mode occurs in epilepsy, stress and pain models ¹⁸.

Central sensitization

The physiologic and clinical results of the above described processes lead to amplification of evoked pain and an increase in spontaneous pain. In the majority of patients it is secondary to facilitation of synaptic transmission in pain transition neurons ¹⁹ in concert with disinhibition.

Central sensitization is manifest by:

1. a lower threshold to fire pain transition neuronss;
2. an increase in their receptive field size;
3. dynamic tactile allodynia; and
4. secondary hypersensitivity.

Presynaptic change in nociceptor afferents include ²⁰:

1. an increase in the synthesis of neurotransmitters and neuromodulators as well as enlarged axons and pore release sites;
2. calcium channel density (necessary for the release of neurotransmitter).

Prominent post-synaptic changes on pain transition neuronss are phosphorylation of the N-methyl-D-aspartic acid receptor that induces an increased Ca2+ concentration and increased post- synaptic AMPA density, as well as enhanced synthesis of ion channels and scaffold proteins in the post synaptic density ²¹. A lack of inhibition both at the dorsal horn level and from the descending nociceptive inhibitory control system, as well as structural modifications and immune neural interaction, contribute to the hyperexcitability throughout the pain matrix that is the hallmark of central sensitization ¹⁹.

Sympathetically-maintained pain

The anatomical and chemical connections between the sympathetic and nociceptive systems occur at the site of injury, the dorsal root ganglion and at almost all levels of the nervous system. Following peripheral nerve injury, sympathetic fibers that innervate blood vessels in the dorsal root ganglion sprout to form basket-like terminals around large dorsal root ganglion neurons (mechanoreceptors) and small pain transition neurons (nociceptors). There is some evidence that high frequency firing of nociceptive afferents upregulate α2 adrenoreceptors on their axons. Experimental studies demonstrate: 1) adrenoreceptor activation of nociceptor afferents; 2) denervation adrenergic hypersensitivity of vascular smooth muscle; 3) adrenergic effects on nociceptor afferents sensitized by bradykinin, prostanoids, and neuro-trophic factors; 4) adrenal epinephrine that sensitizes mechanosensitive afferents and nociceptors ²². In conjunction with sympathetic nociceptive coupling in the periphery, descending adrenergic afferents are an important component of the DNIC (Difuse Noxious Inhibitory Con-trol) system that modifies pain transmission. There are multiple instances in which early sympathetic denervation has cured complex regional pain syndrome ²³.

Role of the immune system in the pain of complex regional pain syndrome

Chronic pain states and complex regional pain syndrome can result from interactions between the immune and nociceptive systems ²⁴. Microglia and astrocytes are the primary immune competent cells in the central nervous system and are activated following nerve, tissue damage or inflammation. Activated glia have been shown to be both necessary and sufficient for enhanced nociception and their activation is an early feature of most neuroinflammatory disorders ²⁵. Neurogenic inflammation and neuroimmune activation act in concert in persistent pain states and are a major component of complex regional pain syndrome ²⁶.

Activated glia and astrocytes secrete proinflammatory cytokines, nitric oxide, excitatory amino acids, prostaglandins and ATP ²⁷. Complex regional pain syndrome patients have elevated cerebrospinal fluid levels of proinflammatory cytokines as well as elevated glutamate and nitric oxide metabolites ²⁸. Scientists have shown in an autopsied patient with longstanding complex regional pain syndrome significant activation of both microglia and actrocytes as well as neural loss in the posterior horn (inhibitory neurons) ²⁹.

Causalgia prevention

These steps might help you reduce the risk of developing complex regional pain syndrome:

• Taking vitamin C after a wrist fracture. Studies have shown that people who take a high dose of vitamin C after a wrist fracture may have a lower risk of complex regional pain syndrome compared with those who didn’t take vitamin C.
• Early mobilization after a stroke. Some research suggests that people who get out of bed and walk around soon after a stroke (early mobilization) reduce their risk of developing complex regional pain syndrome.

Causalgia symptoms

The most common and prominent symptom of causalgia is the pain that affected individuals will feel. The pain is often deep inside the limbs with a burning, stinging, or tearing sensation. Sensory changes are also common, and may include increased sensitivity to painful stimuli, feeling pain from stimuli that are usually non-painful, and in some instances, sensory loss (e.g., numbness).

In addition to pain, patients commonly experience an affected extremity that is warm, red, and swollen, at least initially. In many patients, as causalgia continues, the affected extremity may more often feel cool with dark or bluish skin. Swelling, resulting from fluid build-up in the limb (edema), can be present regardless of the color and temperature of the skin, but is typically more prominent with the early clinical picture (red and warm skin). Skin color and temperature may sometimes change even over short periods of time inconsistently. In addition to the changes above, causalgia patients may experience skin that becomes thin and shiny, and may experience either increased or decreased hair and nail growth in the affected extremity.

Most patients will experience motor impairment, which is the decrease in the ability to use the limbs for movement, with weakness or limited range of motion being the most common impairments. The impairments may be seen in a reduction in strength in handgrip or during tiptoe-standing. Some patients may develop spasms or even uncontrollable muscle contractions (dystonia).

Causalgia complications

If complex regional pain syndrome isn’t diagnosed and treated early, the disease may progress to more-disabling signs and symptoms. These may include:

• Tissue wasting (atrophy). Your skin, bones and muscles may begin to deteriorate and weaken if you avoid or have trouble moving an arm or a leg because of pain or stiffness.
• Muscle tightening (contracture). You also may experience tightening of your muscles. This may lead to a condition in which your hand and fingers or your foot and toes contract into a fixed position.

Causalgia diagnosis

The diagnosis of complex regional pain syndrome is largely clinical and one of exclusion. The differential diagnosis includes small or large fiber sensorimotor neuropathy, cellulitis, erythromelalgia, vasculitis, vascular insufficiency, lymphedema, deep vein thrombosis, and Reynaud’s phenomenon.

The Budapest consensus panel implemented a set of decision rules for proposed clinical criteria. In addition to continuing pain which is disproportionate to the inciting event, they must demonstrate the following symptoms and signs.

They should report at least one symptom in three of the four following categories:

1. Sensory: Reports of hyperalgesia and/or allodynia,
2. Vasomotor: Reports of temperature asymmetry and/or skin color changes and/or skin color asymmetry,
3. Sudomotor/edema: Reports of edema and/or sweating changes and/or sweating asymmetry,
4. Motor/trophic: Reports of decreased range of motion and/or motor dysfunction (weakness, tremor, dystonia) and/or trophic changes (hair, skin, nails).

Additionally, they must display at least one sign at the time of evaluation in two or more of the following categories:

1. Sensory: Evidence of hyperalgesia (to pinprick) and/or allodynia (to light touch or deep somatic pressure),
2. Vasomotor: Evidence of temperature asymmetry and/or skin color changes and/or asymmetry,
3. Sudomotor/edema: Edema and/or sweating changes and/or sweating asymmetry,
4. Motor/trophic: Evidence of decreased range of motion and/or motor dysfunction (weakness, tremor, dystonia) and/or trophic changes (hair, skin, nails).

Finally, there is no other diagnosis that better explains the signs and symptoms.

Various objective testing measures have been utilized to include thermography, triple phase bone scan, and the quantitative sudomotor axon reflex test. While these studies provide further data, they are not necessary to make the diagnosis of complex regional pain syndrome.

Causalgia treatment

Although there is a possibility that patients with complex regional pain syndrome may spontaneously improve, considering the debilitating nature of this syndrome, it is prudent to institute aggressive management as soon as possible as a delay may result in an unfavorable outcome. Comprehensive treatment involves a multidisciplinary strategy with a rehabilitation program at the forefront, so referral to a pain management clinic with these capabilities is ideal ³⁰.

Physical and occupational therapy including mirror therapy is imperative in the treatment of complex regional pain syndrome. The goal of treatment is to manage the pain and to increase mobility of the affected limbs.

Drug treatments considered standard therapeutic options include oral corticosteroids (for warm complex regional pain syndrome), anticonvulsants (ie, gabapentin), analgesic antidepressants (ie, duloxetine), transdermal lidocaine, and opioids. A multimodal pharmacologic regimen that combines several different classes may be superior.

The 2013 Cochrane Review of Interventions for complex regional pain syndrome concluded that although a broad range of therapeutic approaches have been proposed for the treatment of complex regional pain syndrome pain and disability, there is a critical lack of high-quality evidence evaluating the effectiveness of most of these therapies ³¹. Despite this, procedural interventions may be helpful when timed correctly and utilized in a multidisciplinary setting. Serial sympathetic ganglion blocks, either with local anesthetic or chemical/thermal neurolysis, are often utilized to provide relief; yet, despite their widespread use and several case reports and series touting their benefit, when reviewed systematically they have not been shown to provide significant long-term improvement. Still, when timed very early on in the course of CPRS they might convey substantial benefit, such as demonstrated by Gungor et al ³². Sympathetic and perineural blockade with or without a catheter may enable patients to tolerate physical therapy and occupational therapy if administered beforehand. Neuromodulation usually is considered after sympathetic nerve blockade has been attempted. While the literature overall reflects positively on spinal cord stimulation for complex regional pain syndrome, especially in complex regional pain syndrome with an sympathetically-maintained component, an randomized control trial comparing spinal cord stimulation to physical therapy found that the spinal cord stimulation group performed no better than physical therapy alone 5 years after implantation. Intrathecal drug delivery systems are typically considered salvage therapy. Intravenous regional sympatholytic blocks with guanethidine and reserpine have not been supported by randomized control trials, and there is moderate quality evidence that intravenous regional blockade with guanethidine is not effective. With respect to intravenous infusions in particular, a 2016 review concluded that while there is evidence to support infusions of ketamine, lidocaine, bisphosphonates, and immunoglobulin as being efficacious, the authors noted that most of the included studies were pre- Budapest Criteria and several were not of high quality ³³.

Because of the association with comorbid psychiatric disorders such as depression and anxiety, cognitive behavioral therapy is considered a necessary component in treating complex regional pain syndrome, although there are no available studies to provide evidence to support the use of this treatment approach. Still, the treating clinician should appreciate that suboptimal management of psychological comorbidities serves as a barrier to improvement for any chronic pain condition.

Additional treatment options include topical capsaicin, free radical scavengers (topical dimethylsulfoxide, oral vitamin C), and surgical sympathectomy.

Patients with the sympathetically-independent variant may have a worse prognosis.

It’s possible for complex regional pain syndrome to recur, sometimes due to a trigger such as exposure to cold or intense emotional stress. Recurrences may be treated with small doses of an antidepressant or other medication.

Therapies

• Heat therapy. Applying heat may offer relief of swelling and discomfort on skin that feels cool.
• Topical analgesics. Various topical treatments are available that may reduce hypersensitivity, such as over-the-counter capsaicin cream, or lidocaine cream or patches (Lidoderm, LMX 4, LMX 5).
• Physical or occupational therapy. Gentle, guided exercising of the affected limbs or modifying daily activities might help decrease pain and improve range of motion and strength. The earlier the disease is diagnosed, the more effective exercises might be.
• Mirror therapy. This type of therapy uses a mirror to help trick the brain. Sitting before a mirror or mirror box, you move the healthy limb so that the brain perceives it as the limb that is affected by complex regional pain syndrome. Research shows that this type of therapy might help improve function and reduce pain for those with complex regional pain syndrome.
• Transcutaneous electrical nerve stimulation (TENS). Chronic pain is sometimes eased by applying electrical impulses to nerve endings.
• Biofeedback. In some cases, learning biofeedback techniques may help. In biofeedback, you learn to become more aware of your body so that you can relax your body and relieve pain.
• Spinal cord stimulation. Your doctor inserts tiny electrodes along your spinal cord. A small electrical current delivered to the spinal cord results in pain relief.
• Intrathecal drug pumps. In this therapy, medications that relieve pain are pumped into the spinal cord fluid.
• Acupuncture. The insertion of long, thin needles may help stimulate nerves, muscles and connective tissue to increase blood flow and relieve pain.

Physical therapy and occupational therapy are considered first-line treatments for complex regional pain syndrome. Some available therapeutic methods that can be used include desensitization, strength and flexibility training, vocational support, coping skills training, postural control, gait retraining, enhancing ability to carry out daily activities, and relaxation techniques. Another possible rehabilitation method that can be used is graded motor imagery. This method is used to train the brain to enhance motor coordination and function of the limbs that are affected. There are few downsides to physical therapy and occupational therapy for complex regional pain syndrome, except for cost and convenience, and it is suggested that a patient newly diagnosed with complex regional pain syndrome should seek out therapists.

Pharmacologic therapy

Pain is a major concern with complex regional pain syndrome, and this can be managed with a variety of medications that can reduce and control the pain. Pain management is important so that a patient with complex regional pain syndrome can undergo physical therapy with minimal pain.

Doctors use various medications to treat the symptoms of complex regional pain syndrome.

Pain relievers. Over-the-counter (OTC) pain relievers — such as aspirin, ibuprofen (Advil, Motrin IB, others) and naproxen sodium (Aleve) — may ease mild pain and inflammation.

• Your doctor may prescribe stronger pain relievers if OTC ones aren’t helpful. Opioid medications might be an option. Taken in appropriate doses, they might help control pain.
• Antidepressants and anticonvulsants. Sometimes antidepressants, such as amitriptyline, and anticonvulsants, such as gabapentin (Neurontin), are used to treat pain that originates from a damaged nerve (neuropathic pain).
• Corticosteroids. Steroid medications, such as prednisone, may reduce inflammation and improve mobility in the affected limb.
• Bone-loss medications. Your doctor may suggest medications to prevent or stall bone loss, such as alendronate (Fosamax) and calcitonin (Miacalcin).
• Sympathetic nerve-blocking medication. Injection of an anesthetic to block pain fibers in the affected nerves may relieve pain in some people.
• Intravenous ketamine. Some studies show that low doses of intravenous ketamine, a strong anesthetic, may substantially alleviate pain.

Anticonvulsants may be useful in treating pain that is associated with damage or injury to nerves (neuropathic pain). Drugs such as gabapentin and pregabalin are options for treating neuropathic pain. These drugs have modest effects for the reduction of pain. Topical creams containing lidocaine can also be used for neuropathic pain.

Another standard treatment for complex regional pain syndrome is certain types of antidepressant drugs, even if a patient is not depressed. These drugs cause chemical changes in the brain that may help reduce pain and also improve sleep, a common problem among complex regional pain syndrome patients.

Bisphosphonates may be beneficial in patients with complex regional pain syndrome. Bisphosphonates work by inhibiting the breakdown of bones by cells called osteoclasts; however, it is unlikely that bisphosphonates help with complex regional pain syndrome pain by this mechanism. Regardless of the mechanism of action, bisphosphonates, such as alendronate, have shown efficacy in reducing complex regional pain syndrome pain, although they are not often used in complex regional pain syndrome treatment at the present time.

Glucocorticoids (steroid medications) are another treatment option for complex regional pain syndrome. There is some evidence that they may be effective at least in the early stages of complex regional pain syndrome (a few months). In patients who have had complex regional pain syndrome for a longer duration (chronic complex regional pain syndrome), glucocorticoid treatments may have no beneficial effects.

Opioids may also be used for complex regional pain syndrome; however, there are very few studies that have investigated the use of opioids for complex regional pain syndrome. The studies that have been done with opioids do not show that they are effective. The use of opioids may be considered if other options have failed, although opioid medications may carry significant risks.

Interventional procedures

Certain procedures may be required for those who find noninvasive treatments, such as medications and physical therapy, ineffective.

Sympathetic nerve blockade can be used to block the nerves of the sympathetic nervous system. With this nerve blockade, local anesthetics, such as lidocaine, are injected to block the nerves, which may result in a decrease in pain sensation for some patients. There is little research evidence to show its benefits for complex regional pain syndrome as a whole, but it has been reported to work and be life-changing in some patients.

Spinal cord stimulation may be beneficial for patients who have not adequately responded to the interventions above. Spinal cord stimulation uses an electric pulse stimulation to control the transmission of pain signals in the spinal cord. This treatment is relatively safe and reversible, but may be expensive.

Coping and support

Living with a chronic, painful condition can be challenging, especially when — as is often the case with complex regional pain syndrome — your friends and family don’t believe you could be feeling as much pain as you describe. Share information from reliable sources about complex regional pain syndrome with those close to you to help them understand what you’re experiencing.

Follow these suggestions to take care of your physical and mental health:

• Maintain normal daily activities as best you can.
• Pace yourself and be sure to get the rest that you need.
• Stay connected with friends and family.
• Continue to pursue hobbies that you enjoy and are able to do.

If complex regional pain syndrome makes it difficult for you to do things you enjoy, ask your doctor about ways to get around the obstacles.

Keep in mind that your physical health can directly affect your mental health. Denial, anger and frustration are common with chronic illnesses.

At times, you may need more tools to deal with your emotions. A therapist, behavioral psychologist or other professional may be able to help you put things in perspective. He or she may also be able to teach you coping skills, such as relaxation or meditation techniques.

Sometimes joining a support group, where you can share experiences and feelings with other people, is a good approach. Ask your doctor what support groups are available in your community.

Causalgia prognosis

The prognosis for complex regional pain syndrome varies highly from person to person. Early treatment, particularly rehabilitation, may help with limiting the disorder. Younger people, children, and teenagers tend to have better outcomes. Some older adults have good outcomes while others continue to experience severe pain despite treatment.

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