Abstract
Chronic pain is described as a manifestation of real or potential tissue damage. It is identified as a perception influenced by the complex interactions of biological, psychological, and social factors. Different types of pain and their comorbidities dramatically affect patients' quality of life and their families. Due to diverse etiology and pathogenesis, pain management represents a controversial issue in clinical practice. In 1986, the WHO developed a three-step ladder model based on the use of analgesics for pain management according to pain intensity in a linear up or down movement. Despite its huge value for pain relief, this model has some limitations, and some controversies in the pharmacotherapy of pain management have arisen so far. To bypass these difficulties, the concept of WHO analgesic ladder has been contested and changed into a four bidirectional step model which postulates the use of the invasive procedures (neuromodulatory and neurosurgical procedures). Moreover, with the introduction of the neuromatrix theory for dealing the acute and the chronic pain, the WHO model was newly reinterpreted and changed into a platform analgesic model that includes multimodal pharmacological and alternative treatments applicable to all pain conditions, although excludes the precision therapies. Here, we summarize and revise these concepts in order to propose a new model termed "trolley analgesic model" that will allow adopting tailored therapies with dynamic multimodal approaches for pain management according to 1) the pain intensity, 2) the physiopathology of pain, 3) the complexity of symptoms, 4) the presence of comorbidity, and 5) the physiopathological factors and the social context.