Weakness in the legs is a decrease in muscle strength or a subjective feeling of fatigue in the lower extremities. The symptom occurs when the central or peripheral parts of the nervous system, myoneural synapses, and skeletal muscles are affected. It is possible to establish the cause of the violations according to the results of a medical examination, laboratory and instrumental research methods. Treatment of weakness in the legs involves drug therapy, comprehensive rehabilitation.
Pathology of the nervous system is a common cause of weakness in the legs. Violation of impulse conduction along the central or peripheral motor neurons leads to an objective decrease in muscle strength - flaccid or spastic paresis. Only the lower extremities are affected or the process extends to the hands. In practical neurology, the following conditions occur:
Paresis of the extremities occurs with injuries, they become the result of a violation of the integrity of the conductive pathways (due to injuries, fractures, after operations). With unilateral damage to the spinal cord at the level of the lumbar segments, weakness occurs in one leg (lower monoparesis). When the peroneal nerve is damaged, patients note the drooping of the foot, the gait takes on the appearance of a "rooster" or "chasing".
Among the causes of weakness in the legs, an important place is given to the defeat of the structures of the spinal column. Compression of the nerve roots is caused by osteophytes in osteochondrosis, intervertebral hernias, destroyed vertebral bodies - due to osteoporosis, tuberculosis, metastatic process. This situation is observed in spondylarthrosis, spondylolisthesis (displacement of the vertebral segments).
Pain and weakness in the legs are typical signs of radiculopathy, and their localization corresponds to the affected nerves. A pain syndrome of the type of lumbalgia and lumboischialgia is characteristic, aggravated by movements, weight lifting. The picture is complemented by a violation of sensitivity (numbness, paresthesia), muscle atrophy, vegetative-trophic changes on the side of the lesion.
Hormonal disorders often provoke weakness in the legs, symptoms can be caused by a violation of many types of metabolism - protein, lipid, carbohydrate, energy, electrolyte. There is damage to the muscles, myoneural connections or nerve pathways. The cause of weakness in the legs should be looked for among the following conditions:
With long-term diabetes mellitus, symmetrical distal sensorimotor polyneuropathy is detected. Sensitive disorders (hypo- and paresthesias, pain) are accompanied by weakness of the small muscles of the foot over time, Achilles reflexes decrease or completely disappear. The involvement of the proprioceptive system is indicated by instability in the Romberg position.
Weakness in the legs due to muscle damage occurs not only in endocrine pathology. The etiological structure of myopathies is represented by immunopathological, infectious-inflammatory, metabolic disorders, including hereditary diseases. The following conditions become the cause of myopathic weakness in the legs:
Granulomatous myositis in sarcoidosis is accompanied by slowly increasing weakness of the predominantly proximal muscles of the extremities, knots in the muscles. Any acute respiratory viral infections are manifested by aches and fatigue, myositis with swelling of the muscles, pain is possible. With enterovirus infection, a dermatomyositis-like syndrome is sometimes observed.
Many myodystrophies begin with weakness of the leg muscles - hereditary diseases caused by a mutation in the genes responsible for the synthesis of certain structural proteins. With Duchenne dystrophy, the muscles of the thighs and pelvic girdle are first affected - the gait becomes “duck”, it is difficult for children to climb stairs, to get up from a squatting position. Muscle tone decreases, pseudohypertrophy, flexion contractures occur.
The same symptoms, but with a later development and slow progression, are characteristic of Becker's myodystrophy. The juvenile form of Erb-Roth also debuts with a lesion of the pelvic girdle, weakness of the gluteal muscles. Deep reflexes of the lower extremities gradually disappear. With Davidenkov's myopathy, the muscles of the foot suffer: flexors, abductors. First, there are difficulties when running, then - a "cock" gait, the inability to stand on the heels.
Severe weakness in the legs and fatigue are observed with myasthenia gravis. The disease is based on autoimmune aggression against acetylcholine receptors of the myoneural synapse. Symptoms increase with exertion, decrease after rest, and return again from repeated exertion. The proximal parts of the legs and arms are most often involved, while the tendon reflexes remain unchanged.
The development of myasthenia gravis is associated with a tumor and hyperplasia of the thymus, autoimmune diseases - thyroiditis, rheumatoid arthritis, lupus erythematosus. Predisposing factors include infectious pathology, surgical interventions. An important role is played by the intake of certain medications: aminoglycosides, calcium channel blockers, quinine.
Weakness of the legs as a symptom of vascular disorders accompanies varicose veins, obliterating endarteritis, atherosclerosis of the lower extremities. Expansion of the subcutaneous veins of the lower leg is accompanied by increased fatigue, a feeling of heaviness and fullness, swelling, which increase in the evening. Often there are pains along the affected veins, cramps of the calf muscles.
Typical signs of occlusive lesions of the arteries are rapid fatigue of the legs when walking, "intermittent claudication". Tissue ischemia is manifested by pain, a feeling of numbness and compression in the muscles under load. After rest, the symptoms gradually disappear, but when walking is resumed, they develop again. With obliterating endarteritis, there is weakness in the left or right leg, while atherosclerosis is usually a bilateral process.
Sometimes the cause of weakness in the muscles of the legs is the defeat of the nervous and muscle tissue by toxic substances. Organophosphorus compounds and carbamates (insecticides), which inhibit cholinesterase activity, have a negative effect on the myoneural synapse. The function of nerve fibers and ganglia is disturbed by heavy metals: lead, thallium, mercury, arsenic, tellurium.
Alcoholic polyneuropathy deserves special attention, in which the lower limbs are predominantly affected: the legs first hurt, then weakness appears. Paresis is characterized by muscle hypotension with a sharp decrease in proprioceptive sensitivity, loss of tendon and periosteal reflexes, and ataxia. Muscles atrophy quickly.
Clinical examination data, supported by the results of additional methods, help to understand which disease caused weakness in the legs. The list of diagnostic procedures is determined by a neurologist based on the information obtained during the interview and neurological examination of the patient. The following studies may be performed:
To detect vascular diseases, ultrasound angioscanning, rheovasography are prescribed. Endocrinopathy requires ultrasound of the thyroid and parathyroid glands, adrenal glands, in individuals with myasthenia gravis, the size of the thymus is estimated. Diagnosis of hereditary diseases is carried out by cytogenetic, molecular genetic tests.
Acute conditions, in which there is a sharp weakness in the legs, are usually provoked by strokes and injuries. Urgent measures in violation of vital functions include intubation with mechanical ventilation, stabilization of blood pressure, elimination of cerebral edema. Undifferentiated stroke therapy is carried out with cerebroprotective agents. Suspicion of spinal injury requires immobilization of the cervical spine, transportation on a rigid stretcher.
Treatment of muscle weakness in the legs is aimed at eliminating the cause and pathological mechanisms involved in its development. Therapy of acute conditions and maintenance correction of chronic diseases are carried out with medicines of various groups. With a decrease in strength in the limbs, the use of the following drugs is pathogenetically justified:
Myasthenia requires the appointment of anticholinesterase drugs, with vertebrogenic radiculo- and neuropathies with pain, NSAIDs, B vitamins are used. The rehabilitation program for patients with weakness in the legs includes physiotherapy, massage, and exercise therapy. Comprehensive treatment of paresis involves kinesiotherapy, orthopedic correction.
The need for surgical correction with the removal of the thymus arises in severe myasthenia gravis. Hematomas of the medulla are surgically eliminated, and reperfusion techniques are used for ischemic strokes (selective thrombolysis, endarterectomy, shunting). Decompression surgery is necessary to eliminate compression of the spinal roots.
There is a constant search for new methods of therapy for socially maladaptive and serious diseases. The possibilities of eculizumab in Guillain-Barré syndrome are being investigated. Riluzole has already shown efficacy in the treatment of amyotrophic lateral sclerosis, and there are recommendations for the use of rituximab in patients with myasthenia gravis. Gene and cell therapy are considered promising areas.