Pain
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Clinical Trial
Identification of cut-points for mild, moderate and severe pain due to diabetic peripheral neuropathy.
This study identified discrete categories of pain severity in a sample of patients with painful diabetic peripheral neuropathy (DPN), through derivation of cut-points on a 0-10 scale of pain severity (Brief Pain Inventory-DPN, BPI-DPN). Subjects were participants in a burden of illness survey (N=255). Serlin and colleagues' method establishing cut-points for cancer pain was adapted, considering all possible cut-points between 4 and 8. ⋯ Patients in the three categories differed significantly on patient-rated outcomes (Medical Outcomes Study Short Form-12v2 Mental and Physical Component Summaries and EuroQOL utility score), and on DPN-related healthcare visits (P<0.001). The labels 'mild, moderate and severe' Worst and Average Pain corresponded with patients' ratings of their pain using a verbal rating scale. This research shows that three categories of DPN pain severity can be identified based on interference with daily function, and that these categories are associated with patient outcomes and medical utilization.
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Bone cancer pain can be difficult to control, as it appears to be driven simultaneously by inflammatory, neuropathic and tumorigenic mechanisms. As nerve growth factor (NGF) has been shown to modulate inflammatory and neuropathic pain states, we focused on a novel NGF sequestering antibody and demonstrated that two administrations of this therapy in a mouse model of bone cancer pain produces a profound reduction in both ongoing and movement-evoked bone cancer pain-related behaviors that was greater than that achieved with acute administration of 10 or 30 mg/kg of morphine. This therapy also reduced several neurochemical changes associated with peripheral and central sensitization in the dorsal root ganglion and spinal cord, whereas the therapy did not influence disease progression or markers of sensory or sympathetic innervation in the skin or bone. Mechanistically, the great majority of sensory fibers that innervate the bone are CGRP/TrkA expressing fibers, and if the sensitization and activation of these fibers is blocked by anti-NGF therapy there would not be another population of nociceptors, such as the non-peptidergic IB4/RET-IR nerve fibers, to take their place in signaling nociceptive events.
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Comment Letter Comparative Study
Motor cortex disinhibition in complex regional pain syndrome (CRPS)-a unilateral or bilateral phenomenon?