From pain research to pain treatment: the role of human experimental pain models.

There is no objective measure of a complete pain perception; we can, however, measure different aspects of nociceptive processing and pain perception. Earlier, experimental pain models often only involved induction of cutaneous pain using a single stimulus modality. Recently new experimental models have been developed eliciting various modalities of deep and visceral pain which more closely resemble clinical pain conditions. It is imperative to use multi-modal and multi-structure pain induction and assessment techniques, because a simple model cannot describe the very complex and multi-factorial aspects of clinical pain. Furthermore, it is important to assess pain under normal and pathophysiological conditions. The importance of peripheral and central hyperexcitability for acute and chronic pain has been demonstrated in animals and, to some extent, in humans. However, in spite of our immense knowledge, we still do not know how to prevent and treat this hyperexcitability efficiently. Our understanding of nociceptive mechanisms involved in acute and chronic pain and the effects of anaesthetic drugs or combinations of drugs on these mechanisms in humans may also be expanded using human experimental models. This mechanism-based approach may help us to develop and test therapeutic regimes in patients with acute and chronic pain.