Discussion
myofascial pain, bleeding, OA, Pain, pain, myogenous TMD
VASODILATION, BLEEDING, MYOFASCIAL PAIN, CRANIAL NERVES, COMPLICATION
To the best of our knowledge, this is the first study that shows that DN significantly increases the tissue oxygen saturation (ΔTSI%) of the masseter muscle in individuals with TMD. This increase occurs ipsilateral — but not contralateral (without intervention) — to the intervention.A previous study showed that DN sessions also increased tissue oxygen saturation in the trapezius muscle.The DN technique uses needle insertion as in acupuncture. A study showed that acupuncture in the anterior region of the tibia of healthy women increased blood flow in the tibialis anterior muscle.The use of NIRS has also shown that acupuncture on the Achilles tendon of healthy men increased its blood volume and OA mechanism that may explain the response of increased local muscle blood flow to needle stimulation is the release of vasoactive substances such as CGRP and substance P, activating Aδ and C fibers by the axon reflex and leading to vasodilation in small vessels and increased blood flow.However, some NIRS results showed no significant differences in total hemoglobin and StONote that as StOThe discussion of our results should consider that, in the innervation of the masseter muscle, the proportion of myelinated (A) and unmyelinated (C) afferent fibers of the trigeminal nerve branches is greater than in the spinal nerves. Cranial nerves have relatively few type-C fibers, providing a higher conduction speed of trigeminal nociceptive signaling than spinal nerves and a shorter propagation distance to the head.Some individuals are genetically less susceptible to needle-induced nerve stimulation and are called weak responders. They have excessive amounts of endogenous opioid peptide antagonists or receptor deficiencies.Regarding the pain variable assessed using VAS, we observed a significant increase in the variation of pain intensity perception (ΔVAS) immediately after the DN procedure. The Sham intervention failed to result in any difference in our evaluation of this variable (Pain after an MTP DN procedure is a common complication that usually lasts less than 72 hours and can occur due to damage to muscle fibers and intramuscular nerves, bleeding and transient inflammatory reactions. Therefore, method designs should consider pain after DN if they aim to investigate its therapeutic efficacy as this outcome can overlap with the original myofascial pain and influence patients’ classification.A reviewMTP needling therapies should be part of a broader treatment approach rather than being offered as a single intervention.Analyzing the sample characteristics in this study, most participants who had myogenous TMD were women. Epidemiological studies show the highest prevalence of pain in women.