Current pain and headache reports
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Curr Pain Headache Rep · May 2021
ReviewEvidence of Potential Mechanisms of Acupuncture from Functional MRI Data for Migraine Prophylaxis.
To summarize the clinical neuroimaging evidence pertaining to the potential mechanisms of acupuncture for migraine prophylaxis. ⋯ From a descriptive perspective, converging evidence from recent neuroimaging studies, mainly from functional MRI (fMRI) studies, has demonstrated that when compared with sham acupuncture, verum acupuncture could normalize the decrease of the functional connectivity of the rostral ventromedial medulla-trigeminocervical complex (RVM/TCC) network, frontal-parietal network, cingulo-opercular networks, and default mode network and could normalize sensorimotor network connectivity with sensory-, affective-, and cognitive-related brain areas. These areas overlap with those of the pain matrix. Verum acupuncture works in a more targeted and unique manner compared with sham acupuncture in patients with migraine. These findings from neuroimaging studies may provide new perspectives on the validation of acupoints specificity and confirm the central modulating effects of acupuncture as a migraine prevention treatment. However, the exact mechanism by which acupuncture works for migraine prophylaxis remains unclear and warrants investigation. Future studies with larger sample sizes are still needed to confirm the current results and to further evaluate the complex and specific effects of acupuncture by analyzing different stimulus conditions, such as verum vs. sham acupuncture, deqi vs. no deqi, different acupuncture points or meridians, and different manipulation methods. Moreover, instead of focusing on the changes in a single area of the brain, researchers should focus more on the relationships among the functional connectivity network of brain areas such as the RVM/TCC, thalamus, anterior cingulate cortex (ACC), superior temporal gyrus (STG), and supplementary motor area (SMA) to explore the underlying mechanism of the effects of acupuncture.
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Curr Pain Headache Rep · May 2021
ReviewRepetitive Transcranial Magnetic Stimulation for Treating Chronic Neuropathic Pain: a Systematic Review.
Given pharmacological interventions' limited efficacy and abundance of its adverse effects, the repetitive transcranial magnetic stimulation (rTMS) is considered a viable non-invasive option for managing chronic neuropathic pain of different origins with promising outcomes. PURPOSE OF REVIEW: The provision of a systematic review of current literature on rTMS for managing chronic neuropathic pain of different origins, and assess its efficacy and outcomes, highlighting the need for standard protocols for utilizing rTMS. RECENT Variable stimulation modalities were trialed targeting the M1, DLPFC, and somatosensory cortices S1 and S2. ⋯ The lack of standard methods for rTMS, stimulatory parameters, and target stimulation site precludes concluding the optimal modality for stimulation. The practical algorithm by Lefaucheur and Nguyen (Neurophysiol Clin. 49(4):301-7, 2019) can guide setting standardized algorithms for rTMS. Defining optimal stimulation sites, frequencies, and pulses to maximize patient's pain relief and minimize required rTMS sessions requires further research.
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The number of applications for peripheral nerve stimulation (PNS) in the pain management field is ever-growing. With the increasing number of clinical applications for peripheral nerve stimulation, the purpose of this article is to review the mechanism of action surrounding PNS, the recent literature from January 2018 to January 2021, and pertinent clinical outcomes. ⋯ The authors searched articles identified from PubMed (January 2018-January 2021), Cochrane Central Register of Controlled Trials databases (January 2018-January 2021), and Scopus (January 2018-January 2021) databases, and manually searched references of identified publications. Broad MeSH terms and Boolean operators were queried in each search, including the following terms and their respective synonyms: peripheral nerve stimulation, mechanism of action, biochemical pathway, and pain pathway. 15 consensus articles were selected for in-depth review and inclusion for qualitative analysis. PNS may activate and modulate higher central nervous system (CNS) centers, including the dorsal lateral prefrontal cortex, somatosensory cortex, anterior cingulate cortex, and parahippocampal areas. Neuromodulatory effects from PNS may also extend into the spinal columns. Also, PNS may lead to changes in endogenous neurotransmitters and affect the plasticity of NMDA pathways.
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Curr Pain Headache Rep · May 2021
ReviewRecent Advances in Peripheral Opioid Receptor Therapeutics.
Although opioids are excellent analgesics, they are associated with severe short- and long-term side effects that are especially concerning for the treatment of chronic pain. Peripherally acting opioid receptor agonists promise to mitigate the more serious centrally mediated side effects of opioids, and the goal of this paper is to identify and elaborate on recent advances in these peripheral opioid receptor therapeutics. ⋯ Peripheral opioid receptor agonists are effective analgesics that at the same time circumvent the problem of centrally mediated opioid side effects by (1) preferentially targeting peripheral opioid receptors that are often the source of the pain and (2) their markedly diminished permeability or activity across the blood-brain barrier. Recent novel bottom-up approaches have been notable for the design of therapeutics that are either active only at inflamed tissue, as in the case of fentanyl-derived pH-sensitive opioid ligands, or too bulky or hydrophilic to cross the blood-brain barrier, as in the case of morphine covalently bound to hyperbranched polyglycerols. Recent innovations in peripheral opioid receptor therapeutics of pH-sensitive opioid ligands and limiting opioid permeability across the blood-brain barrier have had promising results in animal models. While this is grounds for optimism that some of these therapeutics will be efficacious in human subjects at a future date, each drug must undergo individualized testing for specific chronic pain syndromes to establish not only the nuances of each drug's therapeutic effect but also a comprehensive safety profile.
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Curr Pain Headache Rep · May 2021
ReviewInterventional Therapies for Pain in Cancer Patients: a Narrative Review.
Pain is a prevalent symptom in the lives of patients with cancer. In light of the ongoing opioid epidemic and increasing awareness of the potential for opioid abuse and addiction, clinicians are progressively turning to interventional therapies. This article reviews the interventional techniques available to mitigate the debilitating effects that untreated or poorly treated pain have in this population. ⋯ A range of interventional therapies and technical approaches are available for the treatment of cancer-related pain. Many of the techniques described may offer effective analgesia with less systemic toxicity and dependency than first- and second-line oral and parenteral agents. Neuromodulatory techniques including dorsal root ganglion stimulation and peripheral nerve stimulation are increasingly finding roles in the management of oncologic pain. The goal of this pragmatic narrative review is to discuss interventional approaches to cancer-related pain and the potential of such therapies to improve the quality of life of cancer patients.