The effectiveness of superficial versus deep dry needling or acupuncture for reducing pain and disability in individuals with spine-related painful conditions: a systematic review with meta-analysis

Chronic spine pain is a common problem that can significantly limit people's quality of life. When conventional treatments such as medications and physical therapy do not provide sufficient relief, many patients and healthcare professionals turn to alternative therapies. Among these options, acupuncture and dry needling have gained prominence for their ability to reduce pain and improve function. Both techniques involve the insertion of fine needles into the skin, but they differ in application depth and in the points chosen for treatment.

The depth of needle insertion is an important issue that has generated debate among researchers and clinicians. Superficial needling involves needle insertion up to 10 millimeters in depth, reaching primarily the subcutaneous tissue just below the skin. This technique is considered safer, more comfortable for the patient, and presents a lower risk of nerve or internal organ injury. On the other hand, deep needling goes beyond 10 millimeters, penetrating muscles and other deeper connective tissues.

Although it may cause more discomfort, this technique is believed to directly reach muscular trigger points and other structures that contribute to pain.

This study was a systematic review with meta-analysis that gathered high-quality scientific evidence to answer a fundamental question: which approach is more effective for the treatment of spine-related pain? The researchers conducted a comprehensive search in four major medical databases, covering studies from the inception of these databases through August 2018. They specifically sought randomized controlled trials that directly compared superficial with deep needling, whether through traditional acupuncture or dry needling. Of the 691 articles initially identified, only 12 studies met the rigorous inclusion criteria, totaling 765 participants.

The researchers carefully analyzed data on pain reduction and improvement in functional disability, following internationally established scientific protocols.

The results revealed important differences between the two approaches. For pain reduction, deep needling demonstrated statistically significant superiority over superficial needling, with a moderate effect that remained consistent across different assessment periods. Immediately after treatment, the effect was small but noticeable. Between one and eleven weeks after the start of treatment, the effect of deep needling became moderate and more pronounced.

Even in long-term assessments, after 12 weeks or more, deep needling continued to show advantages over superficial, although with a slightly smaller effect. Interestingly, both superficial and deep needling produced clinically significant improvements in pain when compared with baseline levels, suggesting that both techniques are beneficial. However, when it comes to functional disability, no significant differences were found between the approaches, although only two studies provided sufficient data for this analysis.

A particularly relevant finding was the importance of treatment location. When the needles were inserted directly in the painful area (local treatment), the benefits of deep needling were more pronounced. Treatment that combined local and distant points also showed moderate and significant effects. Needling applied only to points distant from the pain area, however, showed smaller and non-significant effects, suggesting that the proximity of treatment to the affected region influences its efficacy.

For patients considering these therapies, the results suggest that both acupuncture and dry needling can be valid options for the treatment of spine pain. Deep needling appears to offer additional advantages in pain reduction, especially when applied in the affected region. However, it is important for patients to discuss with their healthcare professionals which approach is most appropriate for their specific case, considering factors such as tolerance to discomfort, existing medical conditions, and the practitioner's experience. For healthcare professionals, these findings provide evidence to guide the choice of technique, although clinical experience and individual patient assessment remain fundamental in decision-making.

It is essential to recognize the limitations of this study, which include the variable quality of the studies analyzed and the lack of standardization across the different techniques employed. All included studies showed risk of bias ranging from unclear to high, primarily due to the difficulty of keeping participants fully blinded to the type of treatment received. In addition, there was considerable variation across studies regarding the exact depth of the needles, treatment duration, and specific techniques used. Some studies defined superficial as 2-5 millimeters, while others used up to 10 millimeters.

Similarly, deep needling ranged from 13 millimeters to up to 10 centimeters in depth. This heterogeneity makes careful interpretation of the results necessary and indicates the need for more standardized, high-quality research for definitive confirmation of the superiority of one technique over another.