The second patient has evidence of post-herpetic neuralgia. Post-herpetic neuralgia is a disease that comes on mostly in patients who are debilitated by disease, such as cancer. A virus present in all of us then comes out and produces vesicles. The normal experience of pain is a very protective one. If one does not have sensation of pain, it doesn't protect you from burning your fingers on a stove or a variety of other things.
Pain can be persistent because of abnormal excitability in the nervous system.
It can also be persistent from other mechanisms. Cutting nerves causes altered excitability and altered transmission in the nervous system and creates new forms of pain. In general, except for short-term situations, such as terminal illness, it's not useful to treat pain by cutting nerves. At the global level, the major problem is availability of basic, cheap medications to provide pain relief. By contrast, in underdeveloped countries not only are small quantities of drugs such as morphine available, but most countries around the world have laws to prohibit the use of morphine in the treatment of pain, acute and chronic.