I often have patients become apprehensive about receiving trigger point dry needling (TDN) combined with their other interventions. Spending time educating the patient breaks their nervousness and allows them to feel more comfortable with this modality. However, how do I explain it to another PT or MD? How do I explain it when I'm treating multiple muscles involved or to something that looks unrelated at first look? How can TDN link a pathological Dx with a movement impairment Dx? The answer can be complicated and obviously multifactorial in nature, however I hope to break down the answer down as:
Trigger Point Dry Needling may effectively help the patient 1. back away from the pain threshold and 2. increase the threshold tolerance by a combination of biomechanical and neurophysiological effects thereby allowing a temporary or even permanent restoration of normal muscle tone, movement, and neuromuscular control over the involved, pathological tissues involved.
Let me break down the above “thesis”:
- Biomechanically:
- TDN can normalize muscle patterns by gaining ROM and motor control. The involved TrP is not locked up and limiting movement. The actin-myosin bridges and thus sarcomeres have resumed normal positioning at rest, allowing the muscle to work normally.
- The pain threshold can also be increased because mechanoreceptors like golgi tendon organs, Pacinian corpuscles, etc that protect the muscle at end ranges and from excessive stress are less facilitated due to the new found ROM and length-tension in the muscle. more range and more function and less need for warning signals in functional and resting positioning. Mechanoreceptors are like the empty gas light that turns on when your obviously low on gas. TDN keeps more gas in the tank and thereby limits the need for the gas light to turn on.
- TDN release (via a LTR) decreases the uneven tension, or pull, on a bony attachment. Now the tug-of-war on the bone can be normalized. This can reduce the positional fault and reset the bone’s corresponding joints to an improved and correct position. This backs away from the threshold because the corresponding joint capsules protective responses can be less facilitated, or active.
- Neurophysiological:
- Several actions are occurring at the dorsal horn of the spinal cord during TDN (all of the exact mechanisms are over my head) that decrease the perceived threat and increase the pain threshold to the involved muscle, synergists, and myotome. This includes hypoalgesia which diminishes the sensitivity to pain in that area and thus allows for less guarding (like an advanced gate-control). This also includes sympathoexcitatory responses such as increases in blood flow and heart rate and hormone release to improve the inflammatory and healing response. Finally, muscle reflexogenic effects occur which decrease the hypertonicity in the muscles.
- Another very important factor may be the alteration in the pain “experience” occurring in the brain and brainstem. Specifically, decreasing the overexcitability of pain fibers that perceive the pain. This is done by lessening the amount the pain fibers respond. Not necessarily changing how pain is perceived, just letting us know its not as big of a deal.
- Finally, alterations in the inflammatory response are present including increased blood flow and healing mediators due by the actual mechanical deformation (microtrauma) of the dry needle to a specific location.
In summary, the rewarding effects occurring locally and throughout the body with TDN are numerous. The combination of biomechanical and neurophysiological effects together demonstrate the potential for powerful and long lasting gains not seen without the aide of TDN.
