Central Pain Modulatory Effects of Dry-Needling in Patients With Non-Specific Neck Pain: a Randomized Controlled Experimental Study

Chronic idiopathic neck pain frequently has a myofascial origin. This cervical myofascial pain is caused by myofascial trigger points (MTrPs). Myofascial trigger points are defined as hyperirritable nodules in a contracture of skeletal muscle fibers, which can cause pain symptoms, motor symptoms as well as autonomic symptoms.

Many chronic pain populations (e.g. chronic whiplash associated disorders, fibromyalgia, chronic low back pain) show impaired pain processing and signs of central sensitisation. Central pain processing is defined as an increased responsivity of the nociceptive neurons in the central nerve system and is characterized by hyperalgesia (increased pain after a painful stimuli), allodynia (pain caused by a non-painful stimuli) and temporal summation (increased pain response after repeated stimuli with the same intensity). Hyperalgesia can be divided in local (increased sensitivity in the area of the complaints) and peripheral (increased sensitivity at remote area's). Furthermore, deficient inhibitory pain modulation can be present in this population. Conditioned pain modulation (CPM) can be measured by combining a painful conditioning stimuli (e.g. cold or heat) on a remote location, with a painful test stimuli.

Cervical myofascial pain is often treated by dry needling (DN). DN is a myofascial treatment technique, which has been gaining interest in recent years. During DN, a thin, solid filiform needle is inserted directly into the MTrP. During this treatment, local twitch responses can be elicited. These are involuntary contractions of muscle fibers, leading to muscle relaxation, an increased local blood flow, recovery of the muscle metabolism and thus a reduction of pain and stiffness. By deactivation of the source of pain, chronification of the pain can be prevented.

Up to this moment, there are no studies that investigated the central effects of DN. The aim of this study is to compare the effects of DN with sham needling on pain intensity, local and peripheral hyperalgesia and CPM, in patients with chronic idiopathic neck pain. Therefore, 100 patients will be recruited. Participants are included based on online questionnaires, a clinical examination of neck and shoulder, and the identification of a MTrP in the upper trapezius muscle. All participants will receive information and have to sign an informed consent form. Participants will be subjected to baseline assessment, which involves measurements of pain scores, hyperalgesia (pressure pain thresholds (PPT) by algometry) and CPM (by combining immersion of the hand in hot water while repeating the PPT). Then, participants will be randomly allocated to either a dry needling group or a sham needling group. The dry needling group will receive a dry needling treatment at the identified trigger point location of the upper trapezius, whereas the sham needling group will receive an intervention in which the needle only penetrates the skin but not the fascia and muscle tissue. The one-time intervention of both groups will take approximately 15 minutes. After the treatment, the baseline measurements will be repeated.