Dryneedlinginactiveorlatenttriggerpointinpatientswithneckpain:arandomizedclinicaltrial

Neck pain is one of the most common musculoskeletal complaints worldwide, ranking as the fourth leading cause of disability. Approximately 70% of people will experience neck pain at some point in their lives, and up to half of those with acute neck pain may develop chronic symptoms. Myofascial trigger points (MTrPs) — hypersensitive spots in taut muscle bands that cause local and referred pain — are believed to play an important role in mechanical neck pain. These trigger points can be classified as "active" (causing spontaneous pain) or "latent" (painful only when compressed).

The upper trapezius muscle is particularly prone to developing MTrPs due to its constant activity and susceptibility to micro-trauma. Dry needling, an invasive technique where thin filiform needles are inserted into muscle tissue, has become a popular treatment for deactivating MTrPs. However, a key clinical question remains: does it matter exactly where the needle is placed? Specifically, is needling directly into an active trigger point superior to needling a latent trigger point or a non-trigger point area in the same muscle?

This study aimed to answer this question by comparing three needling locations in patients with chronic neck pain.

The researchers conducted a randomized, double-blind clinical trial with 65 patients who had chronic non-specific neck pain lasting at least three months. All participants had both active and latent MTrPs in their upper trapezius muscle. Participants were randomly assigned to one of three groups: dry needling at a non-MTrP location (control group, n=21), dry needling at an active MTrP (n=22), or dry needling at a latent MTrP (n=22). The study was double-blinded, meaning neither the patients nor the physiotherapist performing the needling knew which group each participant belonged to.

An evaluating therapist marked the needling site on the skin without revealing the group assignment.

All participants received a single session of deep dry needling with up to 12 needle insertions ("in-and-outs") at a frequency of 1 Hz. The primary outcome was neck pain intensity measured on a 100 mm visual analog scale (VAS) at 11 time points: before, during, immediately after, and at 1, 6, 12, 24, 48, 72 hours, 1 week, and 1 month post-intervention. Secondary outcomes included pressure pain threshold (PPT) at the upper trapezius and at a distant site (tibialis anterior muscle), PPT expansion (summation of both sites), neck disability (Neck Disability Index), number of local twitch responses (LTRs) elicited, and whether the patient's pain was reproduced during needling.

Pain intensity improved significantly over time across all three groups (F = 306.099; P < 0.0001), with a significant group-by-time interaction (F = 3.117; P = 0.0001). The active-MTrP group experienced greater pain immediately post-needling compared to the other groups, but showed significantly lower pain scores than the non-MTrP group at 1 week (P < 0.05). However, by 1 month, there were no significant differences between groups in pain intensity. All groups showed statistically significant improvements from 1 hour post-needling through 1 month (P < 0.01).

For pressure pain threshold at the upper trapezius, all groups improved equally over time (F = 57.607; P < 0.0001) with no significant group differences. However, at the distant tibialis anterior muscle, there was a significant group-by-time interaction (F = 5.786; P = 0.005), with the active-MTrP group showing the least improvement in PPT compared to both other groups (P < 0.05). PPT expansion and neck disability also improved equally across all groups over time, with no significant between-group differences.

Regarding local twitch responses, a higher number of LTRs was significantly associated with pain reproduction during needling (P < 0.05), but not with greater clinical improvement. More LTRs were elicited in the active and latent MTrP groups than in the non-MTrP group (P < 0.0001). Pain reproduction during needling occurred in 77.3% of the active-MTrP group and 81.8% of the latent-MTrP group (P < 0.001), but this did not predict better outcomes. Regression analysis found that lower pain intensity at 1 week was predicted by fewer LTRs and side treated (R² = 0.157; P < 0.001), and lower PPT at the tibialis muscle was predicted by bleeding after needling and needling site (R² = 0.218; P < 0.05).

This study challenges the traditional assumption that precise targeting of active trigger points is essential for effective dry needling. The key finding is that for most outcomes — including overall pain reduction, local pressure pain threshold, disability, and PPT expansion — the location of needling in the upper trapezius muscle does not appear to matter significantly. All three needling locations produced meaningful improvements. The active-MTrP group did show a slight advantage for pain intensity specifically at 1 week, but this difference disappeared by 1 month, suggesting that any location-specific effect is short-lived.

Importantly, the study found no evidence that eliciting more local twitch responses leads to better clinical outcomes, contradicting some traditional teachings about dry needling. While LTRs were more common when needling active and latent trigger points, and were associated with pain reproduction, they did not translate into superior results. In fact, fewer LTRs predicted better pain outcomes at 1 week.

For clinicians, this suggests that dry needling may work through broader mechanisms — possibly involving central nervous system modulation, sympathetic nervous system effects, or generalized local tissue responses — rather than requiring precise MTrP targeting. This could simplify clinical practice, as therapists may not need to identify and needle exact trigger point locations with the precision previously thought necessary. However, the authors caution that these findings apply to a single session in the upper trapezius muscle, and that multiple sessions, other muscles, or longer follow-up periods might yield different results. Future research with larger samples, multiple treatment sessions, and longer-term follow-up is needed to confirm these findings and explore whether they generalize to other muscles and conditions.