Screening Visit During this visit a complete medical check-up, based on universally accepted techniques, will evaluate neuropathic compromise, medications and other therapies used for the treatment of PLP. The inclusion/exclusion criteria will be applied by a neurologist and the selected candidates will be informed about the study. It will be asked to patients to avoid consumption of new analgesic medications during the study development. If one patient requires the introduction of a new analgesic treatment for increased pain or concept of the physician, this will be recorded and taken into consideration in the data analysis.