The journal of pain : official journal of the American Pain Society
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Projections from the periaqueductal gray (PAG) to the rostral ventromedial medulla (RVM) are known to engage in descending pain modulation, but how the neural substrates of the PAG-RVM projections contribute to neuropathic pain remains largely unknown. In this study, we showed somatostatin-expressing glutamatergic neurons in the lateral/ventrolateral PAG that facilitate mechanical and thermal hypersensitivity in a mouse model of chemotherapy-induced neuropathic pain. We found that these neurons form direct excitatory connections with neurons in the RVM region. ⋯ Thus, our findings revealed that somatostatin neurons within the PAG-RVM axial are crucial for descending pain facilitation and can potentially be exploited as a useful therapeutic target for neuropathic pain. PERSPECTIVE: We report the profound contribution of somatostatin neurons within the PAG-RVM projections to descending pain facilitation underlying neuropathic pain. These results may help to develop central therapeutic strategies for neuropathic pain.
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Head and neck pain drawings have been introduced as part of the diagnostic gold standard for temporomandibular disorders (TMD). We aimed to quantify the spatial extent of pain in TMD patients and to analyze its association with further clinical findings. In a cross-sectional study, 90 patients (median age = 38 years; n women = 68) were diagnosed according to the DC/TMD. ⋯ PERSPECTIVE: Head and neck pain drawings can contribute to a stratification of TMD patients. A greater extent of pain as well as pain bilateralization is associated with higher levels of emotional distress, pain chronicity and somatization, but not with functional impairment. Unilateral reporting of pain is associated with more intra-articular disorders.