When the progression of disease lowers opioid requirement in cancer patients

The Gate Theory of Pain Revisited: Modeling Different Pain Conditions with a Parsimonious Neurocomputational Model

The gate control theory of pain proposed by Melzack and Wall in 1965 is revisited through two mechanisms of neuronal regulation: NMDA synaptic plasticity and intrinsic plasticity. The Melzack and Wall circuit was slightly modified by using strictly excitatory nociceptive afferents (in the original arrangement, nociceptive afferents were considered excitatory when they project to central transmission neurons and inhibitory when projecting to substantia gelatinosa). The results of our neurocomputational model are consistent with biological ones in that nociceptive signals are blocked on their way to the brain every time a tactile stimulus is given at the same locus where the pain was produced. In the computational model, the whole set of parameters, independently of their initialization, always converge to the correct values to allow the correct computation of the circuit. To test the model, other painful conditions were analyzed: phantom limb pain, wind-up and wind-down pain, breakthrough pain, and demyelinating syndromes like Guillain-Barré and multiple sclerosis.

Preferences of caregivers and patients regarding opioid analgesic use in terminal care

CONTEXT

Patients and caregivers participate in decision-taking, and their views should be considered in the preparation of Clinical Practice Guidelines (CPGs). We involved them in the development of a CPG on the safe use of major opioids.

OBJECTIVE

To identify the values and preferences of patients and caregivers on the use of opioids and the desired outcomes, to investigate motives for the acceptance/rejection of opioid therapy, and to evaluate their beliefs and information about these drugs.

METHODS

A qualitative study was conducted using semi-structured interviews in an Andalusian population of terminal patients and caregivers (N = 42). Study variables included the role, diagnosis, and adherence to treatment. Content and validity analyses were performed.

RESULTS

Less than one-third of participants recognized the term opioid. Among these, false beliefs were held related to the addictive nature of these drugs, their exclusive use in terminal cases and at the end of life, and their association with premature death. The information received was very general: it was known that they are "useful for pain," and some were informed about the administration route, composition, and habituation. Participation in decision making was usually limited to reporting symptoms to the physician.

CONCLUSION

These patients and caregivers demonstrated a preference for pain alleviation by opioid treatment and gave negative assessments on adverse digestive effects that can cause this treatment to be abandoned. They expressed interest in receiving more information and in participating in therapeutic decision making, and they reported erroneous beliefs and a lack of information about the effects of these drugs.