Peripheral Neuropathy 1. Definition • Damage to the peripheral nervous system (outside the brain and spinal cord) → leads to sensory, motor, or autonomic dysfunction. 2. Causes • Metabolic: Diabetes mellitus (most common in U.S.), hypothyroidism • Toxic: Alcohol, chemotherapy (vincristine, cisplatin), heavy metals • Nutritional: Vitamin B12, folate, thiamine deficiency • Infectious: HIV, Lyme disease, leprosy • Autoimmune: Guillain-Barré, lupus, rheumatoid arthritis • Other: Chronic kidney disea