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One-sided local weakness of the leg muscles
Last reviewed: 23.04.2024
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One-sided local weakness of the leg muscles is often the initial stage of the lesion, which later becomes generalized. This is particularly characteristic, for example, for; amyotrophic lateral sclerosis, which often debuts with one-sided distal or proximal weakness; spinal muscular atrophy (rare), polymyositis and myasthenia gravis.
The causes of local motor defect most often lie in dysfunction of roots, plexuses or peripheral nerves. Motor disorders are usually accompanied by pain and sensitive disorders. With a typical topography of the distribution of disorders and, especially, when there is a classic anamnesis, the diagnosis is usually not in doubt. Difficulties arise when a clinical examination does not reveal typical causes for local disorders, and the distribution of motor disorders is atypical or is not accompanied by a loss of sensitivity.
One-sided weakness of the thigh muscles and hip flexors , caused by lumbar plexus lesion, is observed with retroperitoneal hematoma and diabetes mellitus, which are usually accompanied by severe pain. A similar situation can be detected with the upper subperiosteal traumatic hematoma of the upper part of the ilium. A rare form of lesion of the lumbosacral plexus after X-ray therapy or some retroperitoneal tumors also causes weakness, rarely without pain, but with a corresponding loss of sensitivity. Lesion of the femoral nerve, leading to paresis of the quadriceps femoris and m. Ileopsoas (manifested by the inability to lift the hip and the absence of the knee reflex), accompanied by a loss of sensitivity on the thigh and medial surface of the shin. Such lesions can be observed, for example, after surgical interventions (hernia operation and others). Repeated intramuscular injections in newborns can cause a quadriceps contracture (without a paresis). In adults, injections can lead to paresis of the middle and minor gluteal muscles (Duchenne's limp or Trendelenburg's limp), often without pain.
On the shin, an acute paresis of the posterior flexor of the foot and fingers is observed as the result of ischemia in the lesion of the anterior tibial artery (due to excessive muscular activity or painful, initially ischemic edema of the anterior tibial area). Such a syndrome is characterized initially by the absence of pulsations on the posterior artery of the foot, often accompanied by transient ischemia of the perforating branch of the peroneal nerve, and later by contracture of the anterior muscles leading to a clawed thumb posture (which prevents the development of the hanging foot). A rupture of the Achilles tendon (an extremely painful condition) causes incomplete disturbance of plantar flexion of the foot (as the posterior tibial and fibular muscles act together as flexors of the foot).
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