What is the cause of lower limb weakness (Lower Motor Neuron weakness)?

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Differential Diagnosis for Lower Limb Weakness

Single Most Likely Diagnosis

  • Peripheral neuropathy: This is a common cause of lower limb weakness, often due to diabetes, vitamin deficiencies, or alcohol abuse. It typically presents with symmetric weakness, numbness, and tingling in the distal limbs.

Other Likely Diagnoses

  • Lumbar disc herniation: A herniated disc in the lumbar spine can compress nerves, leading to lower limb weakness, pain, and numbness. This condition is more common in individuals with a history of back pain or trauma.
  • Stroke: A stroke can cause weakness or paralysis of the lower limbs, depending on the location and severity of the brain injury. It is often accompanied by other symptoms such as facial weakness, speech difficulties, and cognitive impairment.
  • Multiple sclerosis: This chronic autoimmune disease can cause demyelination of nerve fibers, leading to a wide range of symptoms including lower limb weakness, numbness, and vision problems.
  • Muscular dystrophy: A group of genetic disorders characterized by progressive muscle weakness and degeneration, often affecting the lower limbs.

Do Not Miss Diagnoses

  • Spinal cord compression: A medical emergency that requires prompt attention, spinal cord compression can cause rapid progression of lower limb weakness, numbness, and loss of bladder and bowel function.
  • Guillain-Barré syndrome: A rare autoimmune disorder that can cause rapid onset of lower limb weakness, often ascending to the upper limbs and potentially leading to respiratory failure.
  • Cauda equina syndrome: A condition caused by compression of the nerve roots in the lumbar spine, leading to lower limb weakness, numbness, and loss of bladder and bowel function.

Rare Diagnoses

  • Amyotrophic lateral sclerosis (ALS): A progressive neurodegenerative disease that affects motor neurons, causing muscle weakness and atrophy, including in the lower limbs.
  • Charcot-Marie-Tooth disease: A group of inherited disorders that affect the peripheral nerves, leading to progressive lower limb weakness, numbness, and deformities.
  • Inflammatory myopathies: A group of autoimmune disorders that cause muscle inflammation and weakness, including in the lower limbs.
  • Neurosyphilis: A rare condition caused by syphilis infection of the nervous system, which can lead to lower limb weakness, numbness, and other neurological symptoms.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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