Hyperalgesia is an increased sensitivity to pain. It is found in phantom pains, myelopathy, causalgia, syringomyelia, multiple sclerosis, tunnel syndromes, polyneuropathies and local damage to peripheral nerves of various origins. It is detected in some mental illnesses, including depression and somatoform disorders. The determination of the cause of hyperalgesia is carried out on the basis of complaints, neurological examination data, ENMG, evoked potentials, imaging and laboratory techniques. Treatment - analgesics, muscle relaxants, blockades, physiotherapy, surgical operations.
Hyperalgesia is intense pain that does not correspond to the strength of the stimulus that causes it. In neurology, it occurs in diseases accompanied by the development of neuropathic pain syndrome. It may be due to damage to the peripheral nerves or the central nervous system. With phantom pains and causalgia, the central and peripheral components are combined with each other.
When pain occurs directly in the affected area, they speak of primary hyperalgesia, in neighboring or distant areas - of secondary. The pains are usually burning. There are the following variants of hyperalgesia:
- Thermal. Occurs on contact with warm or hot objects.
- Cold. Worried about cooling.
- Chemical. It is noted when applying weak solutions of acetic or citric acid.
- Mechanical. It is observed with a light touch with a brush, a prick with a needle.
Static hyperalgesia, provoked by light tapping or pressure, has a breaking or aching character, develops against a background of neurogenic inflammation. With a psychogenic variant of the symptom, there is no anatomical basis, the violation is presumably due to self-perception disorders and vegetative somatic reactions.
Why does hyperalgesia occur?
Mixed neuropathic pain
Phantom pain syndrome appears in the lost part of the body (amputated limb, resected chest), complemented by a sense of the presence of the removed zone. Widespread. Hyperalgesia is burning, squeezing, shooting or twisting, more often occurs in the first weeks or months, less often - years after the intervention. As a rule, proceeds in the form of paroxysms.
Complex regional pain syndrome or causalgia develops against the background of injuries, infections, vascular lesions, and radiation therapy. It occurs in two forms: Zudek's syndrome and "shoulder-hand" syndrome. Hyperalgesia burning, baking, decrease when the limb is immersed in water, applying a wet bandage. Complemented by vegetative-trophic and sensory disorders. Possible contractures, flaccid paresis.
Central neuropathic pain
A common central cause of hyperalgesia is myelopathy, a condition that develops against the background of degenerative processes in the spinal cord. Along with the pain syndrome, sensory disorders, paresis, paralysis, hyporeflexia or hyperreflexia, muscle hypotonicity or hypertonicity, and disturbances in the activity of the pelvic organs are detected. Myelopathy is accompanied by the following conditions:
- Degenerative diseases of the spine: osteochondrosis, intervertebral hernia, spondylosis, spondylarthrosis, spondylolisthesis.
- Traumatic injuries: compression fractures, dislocations and subluxations of the vertebrae, spinal cord injury.
- Vascular damage: violations of the spinal circulation against the background of thrombosis and atherosclerosis.
- Infectious and inflammatory diseases: osteomyelitis and tuberculosis of the spinal column.
- Other pathologies of the spine: tumors, developmental anomalies.
- Metabolic disorders: phenylketonuria, diabetes mellitus, dysproteinemia.
Hyperalgesia is considered a common manifestation of syringomyelia, since sensory neurons are often affected in this disease. There are unilateral or bilateral sensory disturbances, neurotrophic disorders. In addition, the symptom can be observed in multiple sclerosis and the condition after a stroke.
Tunnel Syndromes
They are a type of peripheral neuropathic pain. Include the following diseases:
- Neuropathy of the ulnar nerve. Hyperalgesia in the area of the elbow joint with irradiation along the ulnar side of the forearm, weakness of the hand, numbness of the little finger and ring finger are determined.
- Neuropathy of the radial nerve. With compression at the level of the wrist, the back surface of the thumb hurts, the back of the hand goes numb.
- carpal tunnel syndrome. Due to compression of the median nerve, hyperalgesia, backache and numbness in the palm area occur. Irradiation to the forearm is possible.
- Neuropathy of the peroneal nerve. When the common trunk is involved, a cock's gait, sensory and motor disorders are revealed, covering the back of the foot and the outer surface of the lower leg. With damage to the superficial branch, the gait is normal or slightly changed.
Hyperalgesia
Other peripheral neuropathic pain
Depending on the nature of the pathology, hyperalgesia is observed within the framework of polyneuropathies or occurs locally in the area of damage to certain anatomical structures. As provoking pathologies are considered:
- Demyelination: chronic inflammatory demyelinating neuropathy, Guillain-Barré syndrome.
- Endocrine and metabolic disorders: hypothyroidism, diabetes mellitus, cirrhosis of the liver, severe kidney disease, prolonged hemodialysis.
- Systemic pathologies: SLE, Wegener's granulomatosis, rheumatoid arthritis, Sjögren's syndrome, periarteritis nodosa , Churg-Strauss vasculitis.
- Alimentary diseases: cholelithiasis, alcoholic polyneuropathy, hypovitaminosis B1 and B12.
- Infections: HIV, shingles, hepatitis C and B, leprosy, Lyme disease.
- Hereditary diseases: porphyria, familial amyloidosis, Charcot-Marie disease.
- Immunoglobulinemia: cryoglobulinemia, amyloidosis.
- Toxic effects: heavy metal poisoning, chemotherapy.
Psychogenic hyperalgesia
Exacerbation of pain sensitivity is often observed with mild depression. Patients complain of an increase in the usual painful sensations due to existing chronic somatic pathologies. There are also vague pains of varying intensity, not associated with any diseases. With the aggravation of depressive symptoms, hyperalgesia is replaced by analgesia.
Psychogenic character has pain in somatoform disorders. It is often localized in places of injuries or organs that previously suffered from various acute pathologies (often many years after recovery). In half of the cases, there is no organic basis and no connection with previous diseases. In addition, hyperalgesia is characteristic of hypochondria and hysteria.
With schizophrenia and endogenous depression, a pain syndrome is observed, which increases with movement and forces the patient to remain still. With some mental disorders, imaginary pains and synpsychalgia are detected - painful sensations "assigned" from another person (for example, a loved one broke his leg, the patient suffers from hyperalgesia in the area where the relative has a fracture).
Diagnostics
Diagnostic search is carried out by a neurologist. If the psychogenic nature of hyperalgesia is suspected, the patient is referred to a psychiatrist. In the presence of provoking diseases, consultations of an endocrinologist, rheumatologist, infectious disease specialist and other specialists are required. During the conversation, the doctor finds out when hyperalgesia first appeared, where it is localized, under what circumstances it occurs, and how long it lasts.
Based on the complaints, the neurologist forms a preliminary idea of the disease. The additional examination plan includes such methods as:
- Neurological examination. To confirm hyperalgesia, special tests are carried out (thermal, cold, mechanical, chemical). The specialist evaluates sensitivity and movement, checks reflexes, detects paresis, and other changes characteristic of certain diseases.
- Electrophysiological studies. Electroneuromyography is the gold standard for diagnosing neuropathic pain. Allows you to determine the degree of nerve damage, confirm myelinopathy (involvement of the membrane) and axonopathy. Somatosensory evoked potentials, methods of quantitative sensory testing are also used. With phantom pain, changes in the EEG are observed.
- X-ray studies. Osteoporosis is found in patients with causalgia when performing radiography of the joints of the affected limb. Densitometry is performed to determine bone density. With dorsopathies, stenosis, bone growths, structural changes in hard tissues, and the consequences of traumatic injuries are visible on the pictures of the spine. Myelography is used to confirm syringomyelia.
- Tomography. CT scan of the spine in dorsopathies makes it possible to clarify the size and location of pathological foci, decide on the need for surgery or choose the best option for conservative treatment. On MRI of the spine, soft tissues are clearly visible, which allows you to assess the condition of cartilage, discs, ligaments and other structures. With syringomyelia, cavities are visualized in the region of the spinal cord.
- Laboratory tests. Depending on the provoking pathology in hyperalgesia, tests for hormones are prescribed, PCR, ELISA are performed to detect pathogens of infectious diseases, antibodies are detected in rheumatic processes, blood parameters are studied to determine the severity of impaired liver or kidney function, etc. With the hereditary nature of the disease, genetic tests may be required .
Neurological examination
Treatment
Conservative therapy
With hyperalgesia against the background of somatic, infectious and endocrine pathologies, the underlying disease is treated. As part of the treatment of neuropathic pain, the following are prescribed:
- Painkillers. NSAIDs are recommended for mild to moderate symptoms. Severe pain is considered as an indication for opioids. A serious disadvantage of drugs with analgesic action is the risk of side effects, which limits their use.
- Psychotropic drugs. Allow to reduce nociceptive impulsation, activate antinociceptive mechanisms. Perhaps the use of antidepressants and neuroleptics. With neuralgic pain, a good result is noted when taking anticonvulsants. To stabilize the psycho-emotional state, phytopreparations with a sedative effect are prescribed.
- Other medicines. With dorsopathies, vascular agents, anabolics, chondroprotectors, B vitamins are useful to stimulate recovery and metabolic processes. With syringomyelia, dehydrating agents are indicated. CIDP requires the introduction of glucocorticosteroids.
- Therapeutic blockade. To interrupt the pathological impulses, eliminate the intense pain syndrome, local anesthetics are administered, often in combination with hormones. Taking into account the etiology, localization and prevalence of hyperalgesia, blockades of the nerve plexuses and peripheral nerves, infiltration anesthesia, epidural blockade can be performed.
- Physiotherapy. UHF, drug electrophoresis with analgesics, magnetotherapy, ultraviolet radiation, electrical stimulation, electrosleep, electroanalgesia are used. A positive effect is observed during reflexology, ultraphonophoresis, amplipulse therapy, thermal procedures, mud therapy, hydrotherapy.
- Other methods. Individually selected complexes of physiotherapy exercises are an indispensable part of the treatment of most hyperalgesia. Complete with massage. It is possible to use taping, manual therapy. Amputee patients require early rehabilitation. With dorsopathies, traction therapy is effective.
Surgery
With causalgia, phantom pain, accompanied by hyperalgesia, resistant to conservative therapy, sympathectomy is performed. With dorsopathies, the tactics of treatment are determined by the nature of the provoking disease. With intervertebral hernias, microdiscectomy, radiofrequency denervation of the facet joints, or nucleoplasty are performed.
In case of spinal instability, fixation with cages, interbody fusion, and transpedicular fixation are carried out. If the spinal canal is narrowed, puncture disc decompression, laminectomy, or facetectomy are performed. With osteomyelitis, a sequestrectomy is performed. In tunnel syndromes, nerve decompression may be recommended.