Pain: moving from symptom control toward mechanism-specific pharmacologic management.

Pain is a multidimensional sensory experience that is intrinsically unpleasant and associated with hurting and soreness. It may vary in intensity (mild, moderate, or severe), quality (sharp, burning, or dull), duration (transient, intermittent, or persistent), and referral (superficial or deep, localized or diffuse). Although it is essentially a sensation, pain has strong cognitive and emotional components; it is linked to, or described in terms of, suffering. It is also associated with avoidance motor reflexes and alterations in autonomic output. All of these traits are inextricably linked in the experience of pain. Although we tend to think of pain as a homogeneous sensory entity, several distinct types exist: nociceptive, inflammatory, neuropathic, and functional (Figure 1). The neurobiological mechanisms responsible for these different pains are beginning to be defined (1–3), providing insight into how distinct types of pain are generated by diverse etiologic factors, and in which patients (4). Moreover, we can now realistically expect to move from an empirical therapeutic approach to one that it is targeted specifically at the particular mechanisms of the type of pain experienced by an individual patient. Although current analgesic treatment is aimed at suppressing or controlling symptoms (5), interventions that can abort the development of pain mechanisms are beginning to be conceivable (1).