[Treatment of different types of pain].

Accurate assessment of pain is the key to appropriate analgesia. This necessitates not only an understanding of the organic component, but also a comprehension of the role played by the mental, social and spiritual dimensions in the individual patient's suffering. It implies that the entire care team must be involved in pain management. The nature of a patient's pain is one predictor of the response to treatment. It is mainly characterized by its location, intensity, extent, timing and type (excessive nociception, neurogenic, or mixed), the circumstances in which it appears, and any accompanying signs. The choice of analgesic for treating pain due to excessive nociception was greatly facilitated by the introduction of the WHO three-step approach. Better knowledge of the pharmacological and pharmacokinetic properties of the different analgesics has contributed to increase their efficacy and tolerability. Certain types of pain of neurogenic origin respond poorly to both opiate and non opiate analgesics. They can be treated with other drugs whose mechanisms of action in pain relief are not fully understood. They include the following; antidepressants (amitriptyline, nortriptyline, desipramine and doxepine); anticonvulsants (carbamazepine, phenytoin, valporic acid and clonazepam); antiarrhythmic agents (lidocaine, mexiletine, flecainide and tocainide). The unwanted effects of these different treatments, together with psychological disturbances induced by the underlying disease, can call for the use of antiemetics, laxatives, spasmolytics, glucocorticoids and psychotropic agents (anxiolytics, neuroleptics and antidepressants). Finally, in many cases, better pain relief is obtained by combining drug-based therapy with other interventions such as radiation therapy, neurosurgery, and psychological/behavioral approaches. All these means must be chosen and used according to each individual patient's needs. Pain must be considered as a disease that can and must be eliminated or at least attenuated.