Differential Diagnosis for Sudden Weakness in Lower Leg and Inability to Walk
Single Most Likely Diagnosis
- Peripheral neuropathy or radiculopathy: This is often due to nerve compression or damage, which can cause sudden weakness, numbness, or pain in the lower leg, leading to difficulty walking. Conditions like sciatica or a herniated disk can cause these symptoms.
Other Likely Diagnoses
- Musculoskeletal injuries: Acute injuries such as strains, sprains, or fractures in the lower leg can cause sudden weakness and an inability to walk.
- Vascular conditions: Peripheral artery disease (PAD) or deep vein thrombosis (DVT) can lead to sudden leg weakness due to reduced blood flow or clot formation.
- Infections: Conditions like osteomyelitis or septic arthritis can cause severe pain and weakness in the affected leg, making it difficult to walk.
Do Not Miss Diagnoses
- Stroke or spinal cord infarction: Although less common, a stroke affecting the spinal cord or lower parts of the brain can cause sudden leg weakness. Missing this diagnosis could be catastrophic.
- Guillain-Barré Syndrome: An autoimmune disorder that can cause rapid-onset muscle weakness, often starting in the legs. It's crucial to diagnose early for appropriate treatment.
- Spinal epidural abscess or hematoma: These conditions can compress the spinal cord, leading to sudden neurological deficits, including leg weakness. Prompt diagnosis and treatment are essential to prevent permanent damage.
Rare Diagnoses
- Neuromuscular diseases: Conditions like myasthenia gravis or muscular dystrophy can cause progressive muscle weakness but are less likely to present with sudden onset.
- Toxic or metabolic causes: Certain toxins or metabolic disorders (e.g., hypokalemia, hypermagnesemia) can cause muscle weakness, though they are less common causes of sudden leg weakness.
- Inflammatory myopathies: Diseases like polymyositis or dermatomyositis can cause muscle weakness but typically have a more gradual onset and are associated with other systemic symptoms.