The skin punch biopsies from the pain afflicted area will be fixed in 4% phosphate buffered paraformaldehyde. After freezing, the tissue samples are cut into 50-micron thick sections. Systematically sampled sections immunostained with rabbit anti-human Protein Gene Product 9.5 (a neuron-specific protein), and DAB-marked goat anti-rabbit as the secondary antibody. The sections are then microscoped in an Olympus BX51 light microscope with an Olympus DP71 digital camera and Prior motorized board connected to a computer with Newcast stereology software. Two goals can then be calculated: 1) the number of free nerve endings, which crosses the border between dermis and epidermis per mm 2) the average nerve fibre length density in the epidermis and / or dermis.