Exploring the sex differences in conditioned pain modulation and its biobehavioral determinants in healthy adults

Sex-Gender Differences Are Completely Neglected in Treatments for Neuropathic Pain

As sex-gender differences have been described in the responses of patients to certain medications, we hypothesized that the responses to medications recommended for neuropathic pain may differ between men and women. We conducted a literature review to identify articles reporting potential sex-gender differences in the efficacy and safety of these medications. Only a limited number of studies investigated potential sex-gender differences. Our results show that women seem to achieve higher blood concentrations than men during treatment with amitriptyline, nortriptyline, duloxetine, venlafaxine, and pregabalin. Compared to men, higher rates of women develop side effects during treatment with gabapentin, lidocaine, and tramadol. Globally, the sex-gender differences would suggest initially administering smaller doses of these medications to women with neuropathic pain compared to those administered to men. However, most of these differences have been revealed by studies focused on the treatment of other diseases (e.g., depression). Studies focused on neuropathic pain have overlooked potential sex-gender differences in patient responses to medications. Despite the fact that up to 60% of patients with neuropathic pain fail to achieve an adequate response to medications, the potential role of sex-gender differences in the efficacy and safety of pharmacotherapy has not adequately been investigated. Targeted studies should be implemented to facilitate personalized treatments for neuropathic pain.

Body-site effect on CPM efficiency in healthy subjects: Central vs. peripheral stimulation

Structural changes in the peripheral nerve system in neuropathic states alter sensory capacity of the affected area, thus biasing results of conditioned pain modulation (CPM) responses. The aim of this study was to evaluate CPM efficiency of central (i.e. trunk) vs. peripheral (i.e. limb) application of 'test' and 'conditioning' stimuli. Methods: Healthy volunteers (ages 18-73 yrs) underwent two CPM protocols: 'CPM Limb' and 'CPM Trunk'. Each included two types of test stimuli (Ts) (pressure pain threshold: PPT; and contact heat) conditioned either to hand immersion in cold noxious water (CPM limb), or to noxious contact heat applied on lower back (CPM trunk). Results: Both protocols generated efficient pain inhibition for each of the applied Ts; the PPT-based protocol induced more efficient CPM when the conditioned stimulus was applied on the trunk (p = 0.016). Moreover, the PPT-based CPM responses were significantly correlated (ρ = 0.349; p = 0.007). Conclusions: An efficient CPM induced by both central and peripheral stimulation, along with significant correlation between PPT-based responses, advances using the central 'CPM Trunk' protocol in patients with peripheral neuropathy.

Gender and sex bias in prevention and clinical treatment of women's chronic pain: hypotheses of a curriculum development

This discursive paper focuses on undergraduate medical education's role in tackling gender bias in clinical practice, specifically preventing and managing from a non-biomedical perspective chronic pain in women. A preliminary web search of medical schools' curricula was performed to identify programs content related to gender bias in pain management. The web search included 10 universities' websites selected from the top 10 rankings QS Universities Rankings 2022 for medical schools. Additionally, a questionnaire was sent to all deans of the selected academic institutions to explore the curriculum content further. The web search, and the lack of response from the deans, highlighted that relevant curriculum components on gender bias and chronic pain needed to be implemented. Therefore, this paper introduces an innovative curriculum development approach designed by the multi-professional research team to be implemented in medical school programs. This novel educational strategy could also cross-contaminate other healthcare practitioners' university programs and, thus, stimulate an interprofessional debate into fostering inclusiveness and equal opportunities in health.