- Non-diabetic painful peripheral polyneuropathy with pain which has persisted for a minimum of 3 months, including (i) small-fiber neuropathy, as confirmed by quantitative sensory testing (QST), laser evoked potentials (LEP) or skin biopsy, (ii) chemotherapy induced neuropathy in subjects with stable neoplastic disease, (iii) other, adequately characterized painful peripheral polyneuropathy, based on clinical history and examination