Causalgia is an intense burning pain accompanied by local vasomotor, trophic, and motor disorders. Occurs when peripheral nerves of various etiologies are affected. Occurs with sensory disorders: hyperesthesia, hyperpathy, allodynia. It is diagnosed according to compliance with clinical criteria when the nerve trunk lesion is detected according to the results of ENMG and other possible causes of pain are excluded. The treatment of causalgia is complex, includes pharmacotherapy, therapeutic blockades, physiotherapy techniques, psychotherapy, exercise therapy, hydrokinesiotherapy.
Causalgia was first described in 1855 by N.I. Pirogov under the name “traumatic hyperesthesia”. The term “causalgia” appeared in 1864 in a book by the American physician V. Mitchell and a group of co-authors who studied pain syndrome in gunshot wounds of the extremities during the American Civil War. In 1900, the German surgeon Paul Sudek described secondary post-traumatic trophic disorders in the limb. The similarity of the clinical picture of causalgia and Zudek syndrome was discovered in the middle of the XX century. In 1988, the International Pain Association proposed replacing the term “causalgia” with a more precise formulation – complex regional pain syndrome (CRPS). According to European studies, the prevalence of CRPS is 26 cases per 100 thousand of the population, women suffer 3.5 times more often than men.
In 80-85% of cases, CRPS is caused by injury to the limb, including during surgical interventions. Additional etiofactors are: incorrect reposition of the fracture, insufficient anesthesia, excessively prolonged immobilization, tight plaster application. Causalgia includes variants of CRPS arising from direct damage to the peripheral nerve trunk (type 2 CRPS). Triggers associated with the development of causalgia are:
- Nerve damage: contusion, compression, concussion, complete or partial interruption. Injuries of peripheral nerves are noted in case of limb fractures, dislocations, wounds, operations. Causalgia occurs due to nerve irritation, violation of its trophic function. In the case of a complete interruption of the nerve trunk, the pain syndrome has a central mechanism similar to phantom pain.
- Tunnel syndromes: radial nerve tunnel neuropathy, carpal tunnel syndrome, fibular nerve tunnel neuropathy, etc. Causalgia is caused by compression of the nerve trunk in a narrow anatomical tunnel formed by bones, ligaments, muscles. When the vascular bundle is located next to the nerve trunk, the lesion of nerve tissues has an ischemic component.
- Radiation therapy. Local irradiation is carried out for bone tumors, soft tissue neoplasms, rheumatic diseases. Nerve tissue is very sensitive to radioactive radiation, so radiotherapy has a damaging effect on peripheral nerves.
- Vascular disorders. Venous thrombosis in varicose veins, occlusion of peripheral arteries in obliterating atherosclerosis, obliterating endarteritis, vasculitis lead to a disorder of blood supply to the nerve trunk. Due to chronic circulatory insufficiency, ischemic neuropathy develops.
- Infections. Brucellosis, herpes, HIV, diphtheria often occur with the involvement of nerve trunks, plexuses, spinal roots. Causalgia is caused by inflammatory changes that occur when the nerves are affected by infectious agents.
The mechanism of development of causalgic syndrome is not precisely defined. The primary role of the irritating effect of the etiofactor and the involvement of vegetative fibers in the pathological process is assumed. An integral component of the mechanism of pain is neurogenic aseptic inflammation, which is the result of the release of biologically active substances (histamine, prostaglandins, cytokines) in the area of damage.
Afferent impulses enter the spinal cord, then the thalamus and the cerebral cortex. Nociceptive hyperimpulsation causes the formation of a focus of increased arousal in the cortex, which supports the further chronization of the pain syndrome. The theory of the participation of central structures in the mechanism of pain is confirmed by the fact that causalgia is possible with a complete interruption of the nerve diameter. The trophic disorders accompanying the pain syndrome are caused by the dysfunction of the affected nerve, its vegetative fibers. In the acute period, they lead to vasomotor disorders, and subsequently to dystrophic and atrophic changes in innervated tissues.
According to the clinical variants, causalgia is classified into distal (Zudek syndrome), proximal (cervical-brachial) and widespread — covering the entire limb (shoulder-hand syndrome). The development of CRPS goes through several phases, the understanding of which is necessary for the correct choice of therapeutic tactics. There are three main stages during the course of the disease:
- Acute (2-6 weeks). There is a constant causalgia against the background of pronounced vasomotor disorders. There is swelling, hyperemia.
- Dystrophic (from 6 weeks to 6 months). It is characterized by a decrease in pain syndrome, the appearance and increase of joint rigidity up to the formation of contractures. Hypertrophy, decreased elasticity, hyperkeratosis of the skin are detected.
- Atrophic (more than 6 months). Progressive tissue atrophy, dryness, pallor of the skin, ankylosis of the joints are detected. Pain syndrome is usually absent.
The clinical picture consists of pain, vasomotor, trophic, motor components. In the acute period, there is a burning, baking pain, the duration of which does not correspond to the etiological effect. Pain is provoked by any stimuli (touch, movement), often occurs without a previous trigger. The intensity of the pain syndrome is medium or pronounced. Patients indicate a decrease in pain when moistening the affected limb. A typical symptom of hygromania is that patients hold a limb in water, apply wet bandages.
Sensory disorders are characteristic: hyperpathy — the appearance of discomfort with harmless influences (for example, stroking), allodynia — the perception of any effects as painful, hyperalgesia — hypersensitivity to pain irritations. Vasomotor dysfunction is accompanied by swelling of the tissues. Edema covers the distal parts of the limb, causes smoothness of the skin pattern. The consistency of the edema is dough–like, subsequently more dense.
The vegetative-trophic component is represented by two variants. The first is manifested by hyperemia, an increase in local temperature, hyperhidrosis, accelerated growth of hair, nails, the second — cyanotic pallor, hypothermia, anhidrosis, delayed growth of skin appendages. Causalgia lasting up to six months is characterized by the first type of trophic disorders, over six months — the second. Motor disorders in the initial stages of the disease are associated with pain syndrome, damage to motor nerve fibers. As the symptoms progress, dystrophy of muscle tissue and joint contractures begin to play a leading role in restricting movements. There is a peripheral flaccid paresis of the muscles innervated by the affected nerve. There may be a tremor, convulsive twitching, a feeling of stiffness of movements.
Causalgia dramatically reduces the ability to work of patients, in the absence of treatment leads to permanent disability. Severe pain syndrome in some cases is complicated by pathological changes in character. Patients become sullen, withdrawn, prone to depression or, on the contrary, excited, irritable up to affective states. Possible anorexia, lack of proper nutrition are accompanied by cachexia, hypovitaminosis. The formation of articular contractures and ankylosis leads to complete irreversible restriction of movements, persistent forced position of the limb.
Of great importance is an indication of a history of trauma, compliance of symptoms with clinical criteria, confirmation of nerve damage and exclusion of other causes of pain syndrome. The 2004 clinical criteria developed in Budapest have been adopted as an international standard, their sensitivity is 85%, specificity is 69%. The main stages of diagnosis are:
- Objective inspection. It is carried out by a traumatologist, therapist, neurologist. Confirms edema, hypersensitivity, different coloration and skin temperature of the affected area and the symmetrical section of the healthy side. The restriction of movements is determined.
- Consultation of a neurologist. Diagnoses local sensitivity disorders (hyperalgesia, hyperpathy, allodynia), decreased muscle tone and strength, inhibition of tendon reflexes. The degree of paresis depends on the severity of the nerve damage, the duration of the disease.
- Electroneuromyography. Detects changes in the speed and amplitude of action potentials. Allows you to exclude primary muscle disease, establish the fact and level of nerve damage, assess its severity.
- Radiography of the joint. It is possible to detect large foci of osteoporosis. If necessary, a CT scan of the joint is performed to clarify the diagnosis. Determination of bone density is carried out using densitometry.
- Blood test. To study the state of mineral metabolism, calcium, parathyroid hormone, blood calcitonin are determined. With normal indicators, the dysmetabolic, endocrine nature of the pathology is excluded.
Causalgia is diagnosed when the clinical symptoms meet the minimum diagnostic criteria, and nerve damage is confirmed according to the ENMG data. Differential diagnosis is necessary to identify the nature of causal pathology. Posttraumatic causalgia is differentiated from nerve tumors, infectious-inflammatory, radiation, dysmetabolic, ischemic lesions.
Combination therapy is indicated, including drug treatment, physiotherapy, kinesiotherapy, psychotherapy. Appointments are selected according to the etiology, the stage of the course of CRPS, the prevailing symptoms. Treatment in the acute period is represented by the following components:
- Anti-inflammatory therapy. It is carried out in the presence of inflammatory changes. It is carried out with nonsteroidal anti—inflammatory drugs, in severe cases – glucocorticosteroids.
- Relief of pain. Conventional painkillers can be effective with moderate pain severity. It is possible to temporarily prescribe narcotic analgesics, conduct therapeutic blockades with local anesthetics. With severe hyperalgesia, anticonvulsants give a good effect.
- Treatment of osteoporosis. Radiologically confirmed osteoporosis is an indication for the use of calcitonin, biophosphanates that inhibit bone resorption. Additionally, calcium preparations and vitamin D are used.
- Psychotropic therapy. Antidepressants, anxiolytics relieve anxiety, reduce irritability and anxiety, potentiate analgesic effect, reducing the activity of the opioid endothelial system. Pharmacotherapy is complemented by psychotherapeutic sessions with a psychologist, a psychotherapist.
- Physical therapy. To eliminate the pain syndrome, electrophoresis with analgesics, ultraphonophoresis, electroanalgesia, electroson, reflexotherapy are used. UHF, amplipulsterapy has a positive effect.
- Kinesiotherapy. An early start of physical therapy is recommended. In the acute period, exercises are performed with the contralateral limb. In the future, with severe paresis, passive gymnastics for the joints is shown. Hydrokinesotherapy gives a good effect.
In the dystrophic period, complex therapy includes pharmacotherapy, reflexotherapy, hydrokinesiotherapy. In the atrophic stage, infiltration therapy with proteolytic enzymes, mud therapy, radon baths are carried out. Sympathectomy is an effective method of surgical treatment. Nerve surgery (neurolysis, endoneurolysis, neurotomy) they are capable of provoking increased pain.
Prognosis and prevention
Causalgia may have a favorable prognosis with early onset and complex nature of therapy. In 75% of cases, with local changes, there is a tendency to expand the affected area. Without treatment, the disease progresses to an atrophic stage, contractures and ankylosis of the joints lead to immobility of the limb, disability of the patient. Preventive measures are aimed at preventing damaging effects on peripheral nerve trunks. Compliance with the technique of surgical interventions, correct treatment of fractures and reduction of dislocations is of great preventive importance.