Discussion summary Neurobiology of neuropathic pain

Abstract This is probably the most fundamental question arising in this session. It was argued that the current IASP definition, ‘ Pain due to lesion or dysfunction of the nervous system’, is of little practical use, because it has no clear boundaries. In other words, using this definition it would be very hard to find any pain that cannot be considered to be neuropathic. This is primarily due to the presence of the term ‘ dysfunction’, which has no clear definition itself and may easily be confused with the normal plasticity of the nociceptive system. In addition, there are lesion sites in the nervous system that may induce pain by clearly nociceptive mechanisms: the muscle pain in rigor or spasticity. Thus, the range of potential lesion sites that may be implied in the generation of neuropathic pain calls for a more precise definition. The IASP special interest group on neuropathic pain (NeuPSIG) has founded a subcommittee on classification that is working on both a revised definition of neuropathic pain that is more precise and a grading system that reflects the degree of certainty with which the presence of neuropathic pain can be determined in a given patient. The current working definition is ‘ Pain arising as a direct consequence of disease or lesion affecting the somatosensory system’ .