Benjamin saw the value of inoculation against small pox. Inoculation is the historical method for the prevention of small pox by deliberately placing the virus under the skin. He also launched the first American Medical School, devised a flexible urethral catheter, and identified lead poisoning as a cause of abdominal pain and peripheral neuropathy. Peripheral neuropathy is the result of damage to the peripheral nerves. It often causes weakness, numbness, and pain to the hands or feet.