Brain and nerve = Shinkei kenkyū no shinpo
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Review
[Pharmacological treatment strategy and mirror visual feedback treatment for neuropathic pain].
Neuropathic pain is a debilitating condition, and pharmacotherapy is the most established treatment strategy. A variety of pharmacotherapies is used for neuropathic pain management: however, pharmacotherapies with evidence for analgesic potency are less common. ⋯ We have treated pharmacotherapy-resistant neuropathic pain with neurorehabilitation techniques such as mirror visual feedback (MVF) treatment. Further to our clinical experience using MVF, we discuss the cerebral mechanism associated with neuropathic pain in this study.
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Pain is classified into physical and psychological pain. Physical pain is nociceptive, inflammatory, or neuropathic. Pain can be categorized into acute or chronic pain depending on the duration of pain and mechanism of onset. ⋯ Chronic pain is caused by incurable conditions or requires a long time to heal and is persistent: it includes chronic nociceptive pain, established neuropathic pain, and psychogenic pain. The therapeutic strategies for pain depend on the underlying pathological conditions: (1) For nociceptive pain, analgesics, narcotic analgesics, and nerve block are indicated. (2) For neuropathic pain, supplementary analgesics, but not analgesics, are indicated, and some narcotic analgesics are also effective: the recommended supplementary analgesics include calcium channel alpha-2-delta ligands, tricyclic antidepressants (TCAs), and serotonin-noradrenaline reuptake inhibitors (SNRIs). (3) For psychogenic pain, analgesics and nerve block are not indicated, except in the setting of a placebo effect: in paticular, narcotic analgesics should not be used. Psychological therapy, tranquilizer administration, cognitive behavior therapy, and patient education are indicated for this kind of pain.
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Neuropathic pain is often a consequence of nerve injury due to surgery, cancer, bone compression, diabetes, or infection. This type of pain can be so severe that even the slightest touch can cause intense pain in the affected area. ⋯ In this review, we summarize the roles of the microglia in the functioning of ATP receptors and of the astrocytes in neuropathic pain. Understanding the key functions of the microglia and astrocytes may lead to the development of new strategies for the management of intractable chronic pain.
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Evidence regarding the effectiveness of nerve block in treating neuropathic pain is scarce. However, in actual clinical situations, nerve block has been used as a treatment in combination with other methods, such as pharmacotherapy, psychotherapy, and physiotherapy. The goal of neuropathic pain treatment is not a complete recovery but some improvement in the activities of daily living (ADL) as well as the quality of life. ⋯ Therefore, the use of nerve block should be considered from the onset of pain. In recent years, methods such as ultrasound-guided nerve block and thermocoagulation with pulsed radiofrequency have become more commonly used as safer and more accurate nerve block techniques. This article discusses the current clinical status of nerve block against neuropathic pain.
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Review
[Pathophysiology of neuropathic pain: Na⁺ channel and hyperexcitability of primary afferents].
Neuropathic pain occurs as a result of peripheral neuropathy or peripheral nerve injury. Voltage-gated Na⁺ channels are assumed to play a major role in the pathophysiology of neuropathic pain and have become important therapeutic targets, because they are critical determinants of the excitability of sensory neurons. Nerve injury or disease could induce changes in trafficking, gene expression, and kinetics of Na⁺ channels, resulting in ectopic discharge and increased neuronal excitability. ⋯ Na⁺ channels are attractive targets for studying the pathophysiology of neuropathic pain and for drug development. However, recent advances have been mostly based on basic research. Overcoming the challenges in directly approaching patients with neuropathic pain might advance our understanding of the pathophysiology of pain and aid the development of therapeutic strategies.