The Role of Dry Needling in Physical Therapy — Pain Science
Dry Needling (also known as Trigger Point Dry Needling) is a technique that has quickly become an increasingly popular treatment modality in the manual physical therapy field. Many physical therapists from different health care backgrounds including Physiotherapists, Myotherapists, Osteopaths and Sports Medicine Physicians are using Dry Needling for the clinical management of musculoskeletal conditions and dysfunctions relating to myofascial pain and trigger points. With the growing popularity of Dry Needling in recent times there are now further clinical studies being published to better understand and establish the pain science behind its use and its role in manual physical therapy rehabilitation.
Dry Needling is the use of solid filiform needles (also referred to as acupuncture needles) directed at a myofascial trigger point for therapy of muscle pain relating to myofascial pain syndrome. The dry needling approach is based on Western anatomical and neurophysiological principles, which are not to be confused with the Traditional Chinese Medicine (TCM) technique of acupuncture (Travell & Simons 1999). Dry Needling can reduce local, referred and widespread pain, restore range of motion, improve muscle activation pattern and normalise the chemical environment of active trigger points. The technique is not a standalone modality however when combined with conventional treatment options Dry Needling provides effective results. Dry Needling can accelerate the process of healing, pain reduction and the restoration of normal tissue function. While anecdotal evidence from therapists and clients are well documented it is only in recent times scientific studies are explaining how Dry Needling works. Its effectiveness is still in debate with limited clinical research in the pain science field.
The history of Dry Needling dates back to the 1940’s with Dr. Janet Travell. She identified muscular trigger points and mapped out referral patterns we know today and still use today. She is remembered as President John F. Kennedy’s personal physician and a researcher of the concept of trigger points as a cause of musculoskeletal referred pain. In discovering these trigger points “Wet Needling” was used where a substance (saline solution, botox or corticosteroids) was directed at trigger points via a hypodermic needle to reduce pain. With the help of Karel Lewit in 1979 he discovered that it was not the analgesic substance used in the needle but the needle itself that relieved myofascial pain. From then Dry Needling got its name and was established.
In a study published in the Journal of Orthopaedic & Sports Physical Therapy, researchers analysed the results of the best clinical studies that have been conducted thus far to determine whether or not dry needling helps to reduce neck and arm pain, both common areas for trigger point development. The researchers found that dry needling can be an effective means of pain relief when dealing with myofascial pain syndrome. In a 2011 review, the Physical Therapy Association rated the evidence for dry needling a 3 out of 5, based on the best studies. A formal analysis of 35 trails on acupuncture and dry needling for chronic lower back pain was published by the Cochrane research group in 2005. It found they “may be useful” additions to standard treatment. As stated with most of these clinical studies there is a need for further higher quality research. Mayoral del Moral completed an interesting dry needling study of 40 subjects scheduled for knee replacement surgery. All subjects were examined for the presence of trigger points and randomly assigned to one of two groups. Before surgery subjects in the intervention group received dry needling of their trigger points, while subjects in the control group were not treated. As all patients were anaesthetised, they were truly blinded to the group allocation and intervention. Subjects who were treated with dry needling reported significantly lower pain levels and required fewer analgesics following the surgery.
Any qualified trained therapists with a solid background and education in anatomy, physiology, and pain sciences as prerequisites can learn Dry Needling. The effectiveness of dry needling as a therapeutic modality depends on the clinician’s ability to identify trigger points, experience and practice in tactile technique of needle insertion, knowledge of the local anatomy and anatomical landmarks to avoid structures in the vicinity of the trigger points. No treatment protocol is effective without a proper physical assessment of the patient combined with the clinical reasoning behind the treatment chosen. Often therapists will use an over simplified model to explain how dry needling works to their clients. Some will admit they are not sure how dry needling works but have great results in reducing pain, releasing myofascial trigger points and improving range of motion and function.
So how does Dry Needling work? The main aim of Dry Needling is to appropriately stimulate the body’s nervous system to suppress pain and deactivate trigger points. During the procedure A-delta nerve stimulation takes place as a result of the needle passing through the skin and subcutaneous tissues and this evokes activity in complex endogenous pain-modulating mechanisms (Baldry 2005). Creating a noxious stimulus to the central nervous system and an inflammatory response is one of the theories of the Dry Needling technique. By inserting a needle it activates the body’s own natural autoimmune response to begin a chain of reactions to aid healing. Neurochemicals such as Endorphins and Corticosteroids, are released and the immune system brings white blood cells to the injured area, and red blood cells carrying oxygen and nutrients to the site. Trigger point Dry Needling has been shown to have local and widespread effects on the nervous system.
It has been said that it is favourable to elicit a so-called local twitch response (muscle spasm) which are involuntary spinal cord reflexes. On examination of a trigger point or taut band deep thumb compression can evoke local tenderness, referred pain, or local twitch response. A local twitch response with Dry Needling is the first step in breaking the pain cycle and relaxing contracted muscles. As the technique in a tense muscle may be painful, the nervous system sends the appropriate feedback to the muscle to inhibit or stop its spasm. This spasm is often the area of neuromuscular dysfunctional and pain experienced by the patient. So by achieving an inhibition or ceasing of spasm, dry needling can take away the cause of pain and dysfunction.
In understanding the pain science of Dry Needling and its therapeutic role in physical therapy we must first have a thorough understanding of the nature of myofascial trigger points. Evidence suggests that the first phase of trigger point formation consists of the development of contractured muscle fibers or a taut band, which may or may not be painful. While the exact mechanisms of the taut band formation are not well defined it is predicted it’s caused by an excessive release of acetylcholine (the substance the nervous system uses to activate skeletal muscles) at the motor endplates. Endplate dysfunction has been confirmed by multiple animal model and human studies. Kuan and colleagues found a correlation between the irritability of trigger points and the prevalence of endplate noise.
Trigger points are divided into active and latent trigger points. Active trigger points have local and referred pain away from the trigger point, while latent trigger points do not cause pain. In clinical practice, a trigger point is considered active if the elicit pain is familiar to the patient. Active trigger points are clustered around motor endplates and feature more endplate noise than latent trigger points, which once again supports that active trigger points are more sensitized.
Where does Dry Needling fit in the entire physical therapy rehabilitation program? There are a range of different approaches and techniques within Dry Needling across physical therapy professions. Different dry needling techniques treat various forms of soft tissue dysfunction and reduce peripheral and central sensitization. Initially dry needling is desirable at the beginning to help reduce and break the pain cycle to allow other treatment modalities including exercise therapy to be introduced. A superficial and a deep technique have been described. Superficial needling technique targets primarily peripheral sensory afferents, while deep trigger point dry needling targets mostly dysfunctional motor units.
Dry needling has shown to be effective for tennis elbow, rotator cuff tendonitis, acute and chronic lower back pain, headaches, migraines, whiplash associated disorders and conditions relating to chronic myofascial trigger points. Dry Needling is effective tool in reducing pain medication dependency with chronic pain. It is best used in conjunction with Myotherapy and remedial massage. While dry needling can be very useful in relieving pain it does not necessarily address other biomechanical issues or underlying pathology from where the source of the pain is coming from. Muscular pain may be secondary from joint instability, osteoarthritis or biomechanical issues making physical assessment very important before treatment with Dry Needling.