The local twitch response during trigger point dry needling: Is it necessary for successful outcomes?

This narrative review critically examines the necessity of the local twitch response (LTR) during dry needling of myofascial trigger points. The LTR is characterized by a visible contraction of part of the taut muscle band when the trigger point is stimulated mechanically with a needle or by palpation. Traditionally, many practitioners believe that eliciting multiple LTRs through the rapid and repetitive needle insertion technique is essential for therapeutic success. The review analyzed six clinical studies that specifically investigated the importance of the LTR for pain and disability outcomes.

The studies included two randomized controlled trials, one prospective controlled clinical study, one case-control study, one cohort study, and one quasi-experimental study, totaling 394 participants with myofascial pain syndrome in different body regions. The results revealed surprising findings that challenge established clinical practice. Several studies demonstrated that elicitation of the LTR does not correlate significantly with changes in pain intensity or disability levels. For example, Gerber and colleagues found that the occurrence of the LTR did not distinguish responders from non-responders to treatment, and there was no statistically significant correlation between LTR elicitation and changes in pain.

Similarly, Koppenhaver and colleagues studied 66 patients with low back pain who underwent dry needling of the lumbar multifidus and found no differences between groups in pain or disability, either immediately or after one week of follow-up. These findings are particularly relevant because this is the only study that evaluated the influence of the LTR on both pain and functional disability. The review also highlights significant concerns about adverse effects associated with techniques that aim to elicit the LTR. Post-needling pain was consistently reported in 100% of patients undergoing repetitive needling to elicit LTRs, with a duration that may extend up to 72 hours.

This additional pain is directly related to the number of needle insertions, suggesting that the more attempts to elicit the LTR, the greater the subsequent discomfort. Animal model studies have shown that repetitive needling can cause mechanical damage near the neuromuscular junction, a rapid inflammatory reaction in the muscle, and degeneration of nerve terminals. From a neurophysiological standpoint, the review explores alternative mechanisms that may explain the beneficial effects of dry needling independently of the LTR. The rotational movement of the needle, for example, activates TRPV1 receptors at peripheral nerve endings through mechanotransduction, leading to intracellular calcium waves and increases in extracellular ATP and adenosine that persist for up to 60 minutes.

These antinociceptive effects are mediated by the activation of A1 adenosine receptors and do not require the LTR. In addition, dry needling promotes spinal segmental analgesic effects and activates descending pain control pathways through the release of endogenous opioids. These mechanisms are enhanced by gentle stimulation with needle rotation maintained for 30 seconds, a technique that does not aim to elicit the LTR but has demonstrated superior efficacy in clinical studies with 3-month follow-up. The review also examines manual therapies as an effective alternative.

Studies comparing dry needling with LTR versus manual release of trigger points showed similar results for pain reduction, with no significant differences between groups. Ischemic compression of trigger points, which does not involve needle insertion or LTR elicitation, has also been shown to significantly reduce superficial electromyographic activity. The clinical implications are considerable. The evidence suggests that practitioners may focus on needling techniques that emphasize mechanical stimulation through gentle needle rotation in connective tissue, rather than the repetitive piston-like movement aimed at multiple LTRs in muscle tissue.

This approach can provide equivalent therapeutic benefits with less risk of post-treatment pain and potential tissue damage.