Leprosy is the classic disease where the most visible deformities are due to a lack of feeling pain. The mycobacterium is thought to attack the long nerves of

Leprosy is the classic disease where the most visible deformities are due to a lack of feeling pain. The mycobacterium is thought to attack the long nerves of the arms and legs, which results in the patients being unable to detect damage - resulting in burns, infections and loss of toes/limbs. One of the problems of treating chronic pain is that it doesn't just involve pain nerve fibres, but also the cerebral perception of pain. Patients who have had amputations can have a 'phantom limb' syndrome, where it seems the cerebrum has remapped it's input somewhere else. They can also get phantom limb pain - which given there isn't a limb or nerve fibres shows how difficult it can be to treat chronic pain. [1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3198614/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3198614/