The Physiology of Pain
Bernard J. Dalens, Jean-Pierre Monnet, Yves Harmand in Pediatric Regional Anesthesia, 2019
It is generally accepted that large myelinated fibers can prevent C fibers, with which they synapse, from releasing substance P when they are excited. The final transmission of nociceptive impulses depends on the discharge rate of multireceptive neurons (T cells, representing the “gate” which, in turn, is influenced by the relative amount of activity in large and small fibers. The nociceptive information is then propagated via rapidly conducting fibers (the central control trigger) and activates cognitive processes which modulate the information by way of ascending and descending (inhibitory) fibers. This theory has led to practical applications in medicine with the development of electroanalgesia by peripheral stimulation.
Transcutaneous electrical nerve stimulation
Harald Breivik, William I Campbell, Michael K Nicholas in Clinical Pain Management, 2008
Many different electrical stimulation therapies have now been developed, all working on the same idea. Action potential stimulation therapy mimics the action potential in its electrical waveform. Interferential therapy is a static machine used by physiotherapists, and transcutaneous spinal electroanalgesia and transcutaneous cranial electrical stimulation are claimed to produce analgesia by percutaneously stimulating the spinal cord and brain, respectively. Cutaneous field stimulation uses a flexible plate with needle-like electrodes to electrically stimulate nerve fibers in the superficial skin, and has been developed to treat itch without damaging the skin.
Stimulation-induced analgesia
Nigel Sykes, Michael I Bennett, Chun-Su Yuan in Clinical Pain Management, 2008
To our knowledge, only one RCT has evaluated the effectiveness of TENS for cancer pain. Robb et al.52 conducted a placebo-controlled evaluation of the effectiveness of TENS and transcutaneous spinal electroanalgesia (TSE) on 41 women with chronic pain associated with breast cancer treatment. TSE is a TENS-like device which uses surface electrodes over the spine and pulse frequencies far greater than a standard TENS device.8, 53 TENS and TSE reduced pain when compared to baseline but the effect was no greater than that observed with placebo (sham TSE).
Effect of transcutaneous electrical nerve stimulation on jaw movement-evoked pain in patients with TMJ disc displacement without reduction and healthy controls
Published in Acta Odontologica Scandinavica, 2020
Yuanxiu Zhang, Jinglu Zhang, Lin Wang, Kelun Wang, Peter Svensson
Although some studies have shown no effect of TENS in reducing muscular activity or increasing jaw opening [19, 36], other researchers have claimed the clinical effectiveness of TENS by showing the reduced facial pain or deep pain sensitivity [22], the successful control on acute and chronic pain [37], the relaxed masticatory muscles [37,38], or the increased jaw opening distance in TMD patients [23]. Different theories have been brought forward to explain the TENS effects. One theory is that repetitive muscle contractions caused by the TENS stimulation to motor nerves can increase blood flow and decrease accumulated toxins, which could lead to alleviation of pain [39]. A second theory, in line with the gate control theory, would suggest that nociceptive activity at the level of the dorsal horn (and brainstem) could be inhibited by activity in large diameter and myelinated afferent nerve fibres [40]. Nevertheless, both central and peripheral processes would be likely to be involved in a TENS-related electroanalgesia [41].
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