Acupuncture (superficial dry-needling) as a treatment for chronic postherpetic neuralgia – a randomized clinical trial

Postherpetic neuralgia (PHN) is a painful condition that affects between 5% and 30% of people after an episode of herpes zoster (shingles) and may persist for up to 10 years. This chronic pain is a major therapeutic challenge, as many patients do not achieve adequate relief from the conventional treatments available, which include topical agents such as lidocaine and capsaicin, anticonvulsants, tricyclic antidepressants, and opioids. Faced with this therapeutic gap, many patients and clinicians turn to acupuncture as an alternative treatment, although robust scientific evidence on its efficacy was lacking. This study is the first randomized clinical trial to rigorously investigate the effects of superficial acupuncture (dry needling) for the treatment of PHN, using a control group with an adequate sham procedure.

The investigators conducted a double-blind, randomized, placebo-controlled, two-arm clinical trial. Twenty-six patients with chronic PHN (pain persisting for more than 6 months after the shingles episode) were randomized to receive either real or sham acupuncture. The intervention group received superficial needling at the facet joints corresponding to the affected dermatome, with 0.25 mm × 13 mm needles inserted to a depth of 5–10 mm at a 45-degree angle, left in situ for 5 minutes. The control group received a sham procedure using blunt needles pressed against the skin without penetration.

All participants received two treatment sessions in consecutive weeks and were assessed at baseline and one month after the final treatment. Outcome measures included numeric pain rating scales (0–10), the Neuropathic Pain Symptom Inventory (NPSI), and the SF-36 quality-of-life questionnaire. Blinding was successful, with participants unable to distinguish between real and sham treatments. The results showed that both groups experienced similar and modest reductions in pain levels.

In the real acupuncture group, maximum pain decreased from 8.5 to 7.3 points (a 1.2-point reduction), while mean pain decreased from 6.2 to 5.7 points (a 0.5-point reduction). In the control group, maximum pain decreased from 8.3 to 7.4 points (a 0.9-point reduction) and mean pain from 7.1 to 6.6 points (a 0.5-point reduction). Crucially, no statistically significant between-group differences were detected for any pain measure (p > 0.05). Among the neuropathic pain parameters assessed by the NPSI (superficial spontaneous pain, deep spontaneous pain, paroxysmal pain, evoked pain, and paresthesia/dysesthesia), none showed significant between-group differences.

The only parameter that reached statistical significance was a quality-of-life measure related to 'role limitations due to emotional problems' (p = 0.03), where the acupuncture group showed improvement while the control group worsened. This isolated finding may reflect an effect of acupuncture on emotional well-being, consistent with prior literature on acupuncture and mental health, although more research is needed. The clinical implications of this study are important for patients and clinicians. The results suggest that, while some individual patients may experience pain relief with acupuncture, there is insufficient evidence to support its routine use in PHN treatment.

The absence of significant differences between real and sham acupuncture indicates that any observed benefit may be primarily due to placebo effects, including therapeutic attention, patient expectations, and the ritual of treatment. This study has several important limitations. The relatively small sample size (26 participants) may have been insufficient to detect clinically meaningful differences. The limited number of treatments (only two sessions) may have been inadequate, since meta-analyses suggest that six or more sessions are associated with better outcomes.

Mean symptom duration in participants was approximately 5 years, and patients with more recent symptoms might respond better. In addition, several participants had previously tried acupuncture without success, which could have influenced their expectations.