Journal of neural transmission
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Among painful disorders, migraine is distinguishable by its chronic pathology and episodic clinical manifestation. Only a small percentage of patients with migraine progress to a chronic form of migraine. Both peripheral and central portions of the trigeminal system are involved in the pathophysiology of migraine pain, as they are involved in the processes of peripheral and central sensitization, alongside various subcortical and cortical brain structures. ⋯ Modulation of the brainstem and midbrain pain pathways, in conjunction with the thalamic and thalamocortical pathways, may be critical for the initiation and maintenance of migraine attacks. Several studies using different neuroimaging techniques have demonstrated that brains experiencing migraine undergo plastic changes in both microstructure and macrostructure and in the functioning of cortical networks, which may manifest early in the life of a patient with migraine. Further studies are required to understand how specific these results are to migraine relative to other painful disorders.
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Many pain conditions in patients tend to co-occur, influencing the clinical expressions of each other in various ways. This paper summarizes the main concurrent pain conditions by analyzing the major interactions observed. In particular, co-occurrence will be examined in: visceral pain (especially ischemic heart disease, irritable bowel syndrome, dysmenorrhea/endometriosis and urinary pain), fibromyalgia, musculoskeletal pain and headache. ⋯ Myofascial pain from trigger points can perpetuate pain symptoms from visceral pain conditions and trigger migraine attacks when located in the referred pain area from an internal organ or in cervico-facial areas, respectively. The pathophysiology of these pain associations is complex and probably multifactorial; among the possible processes underlying the mutual influence of symptoms recorded in the associations is modulation of central sensitization phenomena by nociceptive inputs from one or the other condition. A strong message in these pain syndrome co-occurrence is that effective treatment of one of the conditions can also improve symptoms from the other, thus suggesting a systematic and thorough evaluation of the pain patient for a global effective management of his/her suffering.
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The goal of this narrative review was to give an up-to-date overview of the peripheral and central neurostimulation methods that can be used to treat chronic pain. Special focus has been given to three pain conditions: neuropathic pain, nociplastic pain and primary headaches. Both non-invasive and invasive techniques are briefly presented together with their pain relief potentials. ⋯ Patients' selection is still a challenge. Recent consensus-based guidelines for clinical practice are presented when available. The development of closed-loop devices could be of interest in the future, although the clinical benefit over open loop is not proven yet.