Dry Needling and percutaneous TENS for post-needling soreness in myofascial pain

A recent study published in the Brazilian Journal of Physical Therapy examines the benefits of combining two therapies – dry needling and electrical nerve stimulation – for treating chronic neck pain. The research was conducted by a team of Spanish physical therapists led by Jose V. León-Hernández of the Universidad Autónoma de Madrid^[1]León-Hernández JV, Martín-Pintado-Zugasti A, Frutos LG, Alguacil-Diego IM, de la Llave-Rincón AI, Fernandez-Carnero J. Immediate and short-term effects of the combination of dry needling and … Continue reading.

The study involved 62 patients with chronic myofascial neck pain who were randomly assigned to one of two groups. The first group received dry needling (DN) treatment alone, which involves inserting thin needles into trigger points in the muscle. The second group received DN plus percutaneous electrical nerve stimulation (PENS) applied immediately after the needling. PENS delivers a mild electrical current through the needles to stimulate the nerves.

The researchers measured the patients’ self-reported neck pain, range of motion, and disability at several time points up to 72 hours after treatment. They found that the combination of dry needling plus PENS was significantly more effective than dry needling alone at reducing post-needling soreness and neck pain intensity.

Dr. León-Hernández, the lead author, explained that post-needling soreness is a common side effect patients experience with DN treatment. By applying PENS right after the needles are removed, this soreness can be minimized. He said the results suggest that physical therapists using dry needling to treat chronic neck pain may want to consider adding PENS to improve patient outcomes and comfort.

While both groups showed decreased disability scores, there was no significant difference between dry needling alone and the combination treatment. The researchers concluded that PENS specifically targets pain reduction rather than broader physical functioning. They said further studies should investigate optimal PENS dosage and long-term outcomes.

Overall, this rigorous clinical trial provides evidence that combining proven therapies can enhance pain relief for chronic neck pain sufferers. The authors said their findings may give practitioners new clinical strategies to improve patient care.

Learn more about Myofascial Trigger Points

Myofascial Trigger Point Pain

Myofascial trigger points (MTrPs) are hyperirritable spots in taut bands of skeletal muscle tissue. MTrPs are clinically characterized by local tenderness, referred pain patterns, local twitch response elicited by snapping palpation of the taut band, and reproduction of the patient’s symptoms by compressing the trigger point^[2]Fernández-Carnero J. Effectiveness of dry needling with percutaneous electrical nerve stimulation of high frequency versus low frequency in patients with myofascial neck pain. Pain Physician. 2021 … Continue reading.

The underlying pathophysiology of MTrPs is not entirely understood but likely involves excessive acetylcholine release at the neuromuscular junction leading to localized muscle fiber contractions and ischemia. This creates an energy crisis in the muscle fibers, activating nociceptors and triggering the release of inflammatory mediators like bradykinin, substance P, and others.

Myofascial trigger points can be classified as active or latent. Active MTrPs produce spontaneous local or referred pain, while latent MTrPs are painful only when stimulated. Active MTrPs are thought to develop into latent TrPs over time^[3]Hall ML, Mackie AC, Ribeiro DC. Effects of dry needling trigger point therapy in the shoulder region on patients with upper extremity pain and dysfunction: a systematic review with meta-analysis. … Continue reading.

Myofascial trigger points may disrupt motor unit firing patterns, cause muscle weakness and restrict range of motion. The constant barrage of nociceptive signals from active MTrPs can also facilitate central sensitization, leading to hyperalgesia.
Myofascial trigger points are a prevalent cause of musculoskeletal pain, estimated to be involved in 30-85% of patients presenting with pain complaints. Therefore, effective treatment of active Myofascial trigger points is important for managing myofascial pain syndromes.

Mechanisms of Dry Needling

Dry needling refers to the insertion of thin monofilament needles into Myofascial trigger points to deactivate them and relieve pain. This differs substantially from traditional Chinese acupuncture both in purpose and application.

Dry needling is thought to work through several mechanisms:

• Mechanical disruption of contracted muscle fibers using the needle stimulates low-threshold mechanoreceptors, which can inhibit nociceptive signals at the spinal cord level via gate control mechanisms.
• Repeated needling and piston movements induce local twitch responses, which may help relax contractured muscle bands and normalize taut bands. Local twitch responses are associated with better outcomes^[4]Dommerholt J. Dry needling—peripheral and central considerations. Journal of Manual & Manipulative Therapy. 2011 Nov 1;19(4):223-7..
• Needling causes microtrauma, which triggers a local inflammatory response. Inflammatory mediators like substance P are washed out, helping inactivate the TrP.
• Biomechanical effects of needling may improve blood flow and restore oxygenation of ischemic muscle fibers.
• Insertion of the needle also stimulates A-delta nerve fibers, releasing endogenous opioids that inhibit pain transmission in the dorsal horn.

Adverse Effects of Dry Needling

While generally considered safe when performed by properly trained practitioners, dry needling does carry some risks of adverse events. Potential side effects include:

• Post-needling soreness – Most common adverse effect, can last for a few hours up to 2-3 days depending on needling depth and muscle treated. Caused by local tissue damage from needling. Usually self-limiting^[5]Cagnie B, Dewitte V, Barbe T, Timmermans F, Delrue N, Meeus M. Physiologic effects of dry needling. Current pain and headache reports. 2013 Aug;17:1-8..
• Bleeding/bruising – Typically minor and self-limiting if standard precautions are taken. Risk increased with coagulopathies.
• Syncope – Sudden drop in blood pressure leading to dizziness or fainting. Can occur as a vasovagal response to needling, especially in apprehensive patients. Patient should remain supine during treatment.
• Pneumothorax – Rare but serious complication if needling done in proximity to lung pleura in thoracic region. Requires clinical monitoring after treatment.
• Infection – Very rare with proper skin disinfection and single-use disposable needles. Main risks are local site infection or secondary systemic infection.
• Nerve injury – Uncommon but can occur with very deep needling near nerve roots or major peripheral nerves. Neuropraxia, axonotmesis and neurotmesis possible.
• Spinal cord injury – Extremely rare but devastating complication if needles inserted too deeply in paraspinal region. Hematoma, arachnoiditis, nerve root damage reported.
• Other organ injury – Needling should be avoided in proximity of major organs and vasculature due to risk of perforation, hemorrhage.

Proper patient screening, skin disinfection, needling technique, and clinical precautions during and after dry needling can help reduce adverse risks.

However, the potential for serious complications underscores the need for proper training before utilizing this technique clinically. Most risks can be avoided with sufficient anatomical knowledge and experience.

Dr. Marcus Yu Bin Pai

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MD, PhD. Physical Medicine & Rehabilitation Physician from São Paulo - Brazil. Pain Fellowship in University of São Paulo.

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