 The initiation of NPSP can be identified on a time scale i.e. day of surgery, and can be prospectively expected. This leads to possibility of i a better understanding of the evolution of neuropathy following time and ii a study of putative preventive peritraumatic treatments. Thus, NPSP appears as strongly different from other chronic pain syndromes such as diabetes mellitus, chemotherapy for cancer or even post-traumatic for which the time course, mechanisms and psychic interactions are more complex. 