Muscle weakness

A reduction in maximal voluntary muscle strength due to dysfunction of muscle, peripheral nerves, neuromuscular junctions, or central motor pathways.

Causes

• Neuromuscular causes

  • Myasthenia gravis

  • Peripheral neuropathy

  • Muscular dystrophies

  • Inflammatory myopathies

  • Motor neuron diseases

• Central nervous system disorders affecting central motor pathways

  • Stroke

  • Brain injury

  • Spinal cord injury

  • Multiple sclerosis

• Lifestyle and age-related causes

  • Physical inactivity

  • Prolonged immobilization

  • Age-related sarcopenia

  • Deconditioning

• Electrolyte imbalance (K⁺/Ca²⁺/Na⁺/Mg²⁺)

  • Hypokalemia

  • Hyperkalemia

  • Hypocalcemia

  • Hypercalcemia

  • Hyponatremia

  • Hypomagnesemia

• Nutritional causes

  • Protein malnutrition

  • Vitamin D deficiency

  • Vitamin B12 deficiency

• Endocrine causes

  • Hypothyroidism

  • Hyperthyroidism

  • Cushing syndrome

  • Adrenal insufficiency

• Medications causing myopathy or neuropathy

  • Corticosteroids

  • Statins

  • Neuromuscular blocking agents

• Kidney disease

• Heart failure

• Liver disease

• Cancer-associated cachexia

• Chronic systemic inflammatory diseases