Complex regional pain syndrome is a clinical variant of neuropathic pain. It is a pathological condition in the form of a chronic pain syndrome that develops after exposure to a damaging factor and is not limited to the innervation zone of one peripheral nerve. The manifestations of the disease are not proportional to the influencing factor.
Causes of complex regional pain syndrome
Complex regional pain syndrome includes the following components:
- complex (duration of pain syndrome, autonomic, inflammatory, motor, skin and dystrophic changes);
- regional (most cases are associated with a specific area of the body, while the pain may go beyond the site of the initial lesion);
- painful (pain can occur both spontaneously and when exposed to unconditioned stimuli, which usually do not cause it, or abnormally increased sensitivity to stimuli);
- syndrome (a set of symptoms that are interconnected).
The most common complex regional pain syndrome develops after a fracture of the distal bones of the forearm. Risk factors include the trauma itself, immobilization of the limb, as well as central damage to the nervous system (brain neoplasms, stroke, traumatic brain injury, meningitis, amyotrophic lateral sclerosis).
Patients under the influence of traumatic factors develop disturbances in the peripheral and central nervous systems, inflammation, and oxidative stress. The reflex spasm of peripheral vessels occurs, which contributes to the development of autonomic disorders. In patients, the limbs become cold and pale. In the future, the peripheral vessels expand, the skin in the affected area becomes warm. Long-term sympathetic disorders lead to a disorder of microcirculation: tissue nutrition, endothelial function are disturbed, as a result of which less oxygen and nutrients are received, acidosis develops in them (a shift in pH to the acidic side).
Clinical manifestations and diagnosis of the disease
In patients with complex regional pain syndrome, pain develops within one limb. There is a burning sensation, breaking or aching pains in combination with sensory disturbances and vegetative-trophic disorders (edema, discoloration of the skin, local changes in skin temperature, impaired sweating). The growth rate of hair and nails changes, local osteoporosis and movement disorders develop.
Most often, the symptoms of a complex regional syndrome appear immediately, several days or weeks after the injury, less often – a month after the injury. The first stage of the disease lasts 2-3 months. It is characterized by pain syndrome of varying intensity. Patients are worried about the pain of a breaking, throbbing, burning character. It is aggravated by movement and palpation, changes in weather or excitement, under the influence of excessive thermal stimuli.
If the pain is not stopped, it becomes constant, aching. Patients are forced to fix the limb with a bandage or support with a healthy hand. The pain can spread to the entire arm and shoulder joint, and in some cases to the corresponding half of the body. Patients have doubts about their recovery, sleep is disturbed.
Massive edema develops on the dorsum of the hand or foot and the lower third of the forearm or lower leg. It is at first a doughy consistency, but later becomes dense. Some patients are concerned only with pain. They may not have skin discoloration or swelling.
The second stage of the disease develops in 3-6 months. The pain becomes less intense, the numbness of the joints of the hand or foot increases, and stiffness develops in the interphalangeal and metacarpophalangeal joints. This stage is characterized by the following skin changes:
- loss of elasticity,
- change of initial hyperemia with blue discoloration or pallor;
- a gradual increase in atrophy, dryness, glossiness.
Hyperkeratosis (thickening of the stratum corneum of the epidermis) and hypertrichosis (excessive hair growth) often develop.
After 6 months, the third stage of the disease begins. In patients, all tissue structures atrophy, joint contracture develops, and in severe cases, fibrous ankylosis of the small joints of the foot or hand. At all stages of complex regional pain syndrome, patients are emotionally unstable, excitable, prone to depression. They may have suicidal thoughts.
The diagnosis of “complex regional pain syndrome” is made mainly on the basis of the clinical manifestations of the disease. An important diagnostic method is electroneuromyography. It allows you to determine the presence or absence of damage to the peripheral nerve. Doctors can use x-rays to detect signs of “patchy” osteoporosis.
Treatment of complex regional pain syndrome
The first stage of treatment of complex regional pain syndrome mainly refers to the relief of acute pain. It consists in quality pain relief. Patients are prescribed analgesics, traction is performed. In the second phase, rehabilitation treatment is intended for those patients who are not yet able to return to work. It facilitates the transition from primary treatment to a normal lifestyle.
To treat complex regional pain syndrome, doctors use the following drugs:
- tricyclic antidepressants;
In most cases, a good effect is achieved by a combination of rational combined drug therapy with rehabilitation measures. For patients with complex regional pain syndrome, doctors prescribe anticonvulsants. The most effective drug is gabapentin. It provides a moderate to significant effect 8 weeks after starting treatment. Carbamazepine significantly reduces pain intensity.
Antidepressants have an analgesic effect. In the early stages of the disease, neurologists conduct pulse therapy with high doses of corticosteroids. Treatment is most effective in the presence of a pronounced inflammatory process.
Bisphosphonates reduce inflammation, reduce the intensity of pain, the degree of edema. They are effective at all stages of the disease. Doctors individually select the optimal doses of drugs and determine the duration of treatment. Calcitonin has an analgesic effect. It also helps prevent osteoporosis. With moderate pain in combination with edema and autonomic disorders, a short course of treatment with non-steroidal anti-inflammatory drugs (ibuprofen, voltaren, movalis) is carried out. In the presence of intense pain, these drugs are ineffective.
Muscle relaxants (baclofen) may be helpful in treating combined regional pain syndrome. Pain is significantly reduced after intravenous administration of subanesthetic doses of ketamine. In some patients, the severity of pain syndrome decreases after blockade of the stellate ganglion, lumbar sympathetic blockade, or regional intravenous anesthesia.
For external use, patches with 5% lidocaine are often used. In the early stages, in the presence of an inflammatory process, dimethyl sulfoxide is effective. N-acetylcysteine has a positive effect on cold, bluish skin. Neurosurgeons perform the following surgical interventions: sympathectomy, electrical stimulation of the spinal cord, intracranial neurostimulation. Pain intensity decreases after transcranial brain stimulation.
Psychotherapists train patients to control pain, develop the ability to actively participate in the treatment process and rehabilitation. They use the technique of cognitive-behavioral therapy, relaxation with biofeedback. Rehabilitation therapists perform electrotherapy, manual therapy. Acupuncture also helps to reduce pain.
Early movement therapy has a positive effect on the function of the injured limb. In the acute stage of the disease, exercises can only be performed with a healthy arm or leg. In the second stage, passive gymnastics of the finger joints is carried out. Restores coordination of movements and fine motor skills in weaving or embroidery.