Differential Diagnosis for Leg Weakness

• Single most likely diagnosis:
  • Peripheral neuropathy: This is a common cause of leg weakness, often due to diabetes, vitamin deficiencies, or alcohol abuse. It typically presents with gradual onset of weakness, numbness, and tingling in the legs.
• Other Likely diagnoses:
  • Muscular dystrophy: A group of genetic disorders characterized by progressive muscle weakness and degeneration, often affecting the legs.
  • Chronic inflammatory demyelinating polyneuropathy (CIDP): An autoimmune disorder that causes progressive weakness and numbness in the legs.
  • Lumbar disc herniation or spinal stenosis: Compression of the spinal cord or nerve roots can cause leg weakness, pain, and numbness.
  • Stroke or transient ischemic attack (TIA): Although less common, a stroke or TIA can cause sudden onset of leg weakness, often accompanied by other symptoms such as facial weakness or speech difficulties.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed):
  • Guillain-Barré syndrome: A rare autoimmune disorder that can cause rapid onset of leg weakness, potentially leading to respiratory failure if not promptly treated.
  • Spinal cord compression or cauda equina syndrome: Compression of the spinal cord or nerve roots can cause sudden onset of leg weakness, numbness, and bowel or bladder dysfunction, requiring urgent medical attention.
  • Vasculitis (e.g., giant cell arteritis or polyarteritis nodosa): Inflammation of the blood vessels can cause leg weakness, pain, and other systemic symptoms, and can be life-threatening if not treated promptly.
• Rare diagnoses:
  • Amyotrophic lateral sclerosis (ALS): A progressive neurological disorder that affects motor neurons, causing muscle weakness and atrophy, including in the legs.
  • Tick-borne illnesses (e.g., Lyme disease or tick paralysis): Certain tick-borne illnesses can cause leg weakness, numbness, and other neurological symptoms.
  • Heavy metal poisoning (e.g., lead or arsenic poisoning): Exposure to heavy metals can cause leg weakness, numbness, and other systemic symptoms.
  • Mitochondrial myopathies: A group of rare genetic disorders that affect the mitochondria, causing muscle weakness and degeneration, often affecting the legs.