Pain
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Trigeminal neuralgia (TN) is a rare but debilitating disorder characterized by excruciating facial pain, with a higher incidence in women. Recent studies demonstrated that TN patients present mutations in the gene encoding the Ca V 3.2 T-type calcium channel, an important player in peripheral pain pathways. We characterize the role of Ca V 3.2 channels in TN at 2 levels. ⋯ The effect of Z944 was absent in Ca V 3.2 -/- mice, indicating that Ca V 3.2 is the molecular target of the antihyperalgesic Z944 effect. Finally, enzyme-linked immunosorbent assay analysis revealed increased Ca V 3.2 channel expression in the spinal trigeminal subnucleus caudalis. Altogether, the present study demonstrates an important role of Ca V 3.2 channels in trigeminal pain.
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Central neuropathic pain is a core clinical sign of syringomyelia in humans and Cavalier King Charles Spaniel (CKCS) dogs. This histopathological study used spinal cords from CKCS dogs with syringomyelia to investigate the following conditions: (1) whether specific structural cervical spinal cord entities involved in nociception were affected by loss of neuroparenchyma or other pathological changes in CKCS dogs with pain-related behaviour and phantom scratching, (2) whether pain-related behaviour or phantom scratching correlated with loss of a specific anatomical entity or upregulation of glia cells, and (3) whether syringomyelia-related lesions affected specific functional spinal cord units of nociception. Spinal cord segments C1-C8 from CKCS dogs with magnetic resonance imaging-confirmed syringomyelia and clinical signs of pain and phantom scratching (n = 8) were compared with those from CKCS dogs without syringomyelia (n = 4). ⋯ A clear pattern of ipsilateral changes in the dorsal root entry zone characterised by deafferentation and reorganization of first-order axons into deeper laminae was found in cases with lateralised scratching. Significant changes in cell number density were not found for astrocytes or microglia, suggesting that the dogs represented cases of end-stage syringomyelia and thus could not reveal astrogliosis and microgliosis, which may be involved in the early phases of syrinx development and phantom scratching. The present relationship between clinical findings and dorsal horn and pain pathway pathology in CKCS dogs suggests that these dogs may be of interest as a supplement to experimental model pain research.
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Recent cross-sectional studies have identified differences in autobiographical memory (AM) among individuals with chronic pain, but the temporal relationship between the 2 is unknown. Moreover, AM has yet to be studied in patients undergoing major surgery. This study addressed these gaps by conducting a prospective, longitudinal study of memory performance, postsurgical pain, and psychosocial factors in 97 adult participants scheduled for major surgery. ⋯ Participants who took longer to recall pain memories before surgery (OR = 2.65, 95% CI [1.31-5.37]) and those who produced more surgery-related content at the one-month assessment (OR = 1.31, 95% CI [1.02-1.68]) had greater odds of reporting postsurgical pain up to 12 months later. These findings indicate that presurgical AM biases are risk factors for development and maintenance of postsurgical pain. To the extent that these biases are causal, presurgical interventions that modify the quality and content of patients' memories may prove to be promising strategies in the prevention of chronic postsurgical pain.