It is aimed at myofascial trigger points (MTrP) which are hyperirritable spots in skeletal muscle that are associated with a hypersensitive palpable nodule in a taut band. Trigger point dry needling can be carried out at superficial or deep tissue level.
Superficial dry-needling
This was developed by Peter Baldry. He recommended the insertion of needles to 5-10mm over a MTrP for 30 secs. Palpation of the MTrP then determined the level of response and whether needle stimulation was sufficient to alleviate MTrP pain. If not the need was re-inserted.
Trigger point model
The trigger point model is a dry needling technique that specifically targets myofascial trigger points. They are thought to be due to an excessive release of acetylcholine from selected motor endplates. They can be divided into Active and Latent myofascial trigger points.
Suggested mechanisms of effect:
Stimulation of a local twitch response (LTR)
Dry-needling of these myofascial trigger points via mechanical stimulation causes an analgesic effect. This mechanical stimulation causes a local twitch response (LTR). An LTR is an involuntary spinal cord reflex contraction of the muscle fbers in a taut band. Triggering an LTR has been shown to reduce the concentration of nociceptive substances in the chemical environment near myofascial trigger points.
Muscle regeneration
The needle may cause a small focal lesion which triggers satellite cell migration to the area which repair or replace damaged myofibers. This occurs 7-10 days after dry needling. It is unclear whether continued dry needling within this period may disrupt this process.
A localised stretch to the cytoskeletal structures
This stretch may allow sarcomeres to resume their resting length.
Electrical polarization of muscle and connective tissue
The mechanical pressure causes collagen fibers to intrinsically electrically polarize which triggers tissue remodelling.