Current pain and headache reports
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Chronic low back pain is highly prevalent in Western societies. Large epidemiological studies show that 20% to 35% of patients with back pain suffer from a neuropathic pain component. Presently, chronic lumbar radicular pain is the most common neuropathic pain syndrome. ⋯ Its diagnosis and management remain an enigma, mainly because there is no gold standard for either. Accuracy of diagnostic tests used to identify the source of back pain and their usefulness in clinical practice, particularly for guiding treatment selection, is unclear. In connection with the specific instance of back pain (one of the single most costly disorders in many industrialized nations), neuropathic pain components are a significant cost factor.
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Curr Pain Headache Rep · Jun 2009
ReviewPatent foramen ovale and migraine: association, causation, and implications of clinical trials.
Patent foramen ovale (PFO) appears to be associated with migraine with aura (MA), probably through cardiac shunting. PFOs may also be comorbid with cryptogenic strokes. ⋯ MIST did demonstrate an association between MA and severe PFO shunts prospectively. Difficulty with recruitment closed the MIST II and ESCAPE trials; the PREMIUM and PRIMA randomized controlled trials are ongoing at the time of this writing.
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Migraine pain has been attributed to an episode of local sterile meningeal inflammation and the subsequent activation of trigeminal primary afferent nociceptive neurons that supply the intracranial meninges and their related large blood vessels. However, the origin of this inflammatory insult and the endogenous factors that contribute to the activation of meningeal nociceptors remain largely speculative. A particular class of inflammatory cells residing within the intracranial milieu, known as meningeal mast cells, was suggested to play a role in migraine pathophysiology more than five decades ago, but until recently the exact nature of their involvement remained largely unexplored. This review examines the evidence linking meningeal mast cells to migraine and highlights current experimental data implicating these immune cells as potent modulators of meningeal nociceptors' activity and the genesis of migraine pain.
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Curr Pain Headache Rep · Jun 2009
ReviewContribution of primary afferent channels to neuropathic pain.
Neuropathic pain remains a serious medical problem because of patient morbidity and the absence of effective therapeutic interventions. Recent evidence suggests that this type of pain may be particularly difficult to manage because underlying mechanisms are influenced by a variety of factors, including type of injury, site of injury, and time after injury. This situation is exacerbated by the fact that different mechanisms may contribute to unique aspects of neuropathic pain, including ongoing pain as well as mechanical and thermal hypersensitivity. The different ion channels present in primary afferent neurons implicated in each of these aspects of neuropathic pain are reviewed.
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Nerve injury increases the spinal cord expression and/or activity of voltage- and ligand-gated ion channels, peptide receptors, and neuroimmune factors, which then drive dorsal horn neuron hyperexcitability. The intensity and duration of this central sensitization is determined by the net activity of local excitatory and inhibitory neurotransmitter systems, together with ongoing/evoked primary afferent activity and descending supraspinal control. ⋯ Excessive downregulation or defective compensatory upregulation of these systems may contribute to the maintenance of neuropathic pain. An increasing number of pharmacotherapeutic strategies for neuropathic pain are emerging that mimic and enhance inhibitory neurotransmission in the dorsal horn.