Dry needling (DN) is used by a qualified practitioner such as myotherapist, physiotherapist, osteopath and chiropractor to mainly treat musculoskeletal conditions . This is also called intramuscular manual therapy or trigger point dry needling therapy as the needle penetrates the skin and aims for taut bands known as rigger points.
During a DN session, muscles can twitch by a rapid stimulation on sensitive loci [2,4]. A LTR can induce analgesic effect by descending pain inhibitory pathway [3,4]. Also, when this occurs, abnormal motor end plate activity and excessive acetylcholine release can be restored [5,6].
Is it necessary for practitioners to elicit the LTR?
If you use or have used DN as an intervention, you have probably experienced the LTR. And even if you intend to elicit, it does not happen. Do we even need a LTR? Old papers tend to support the LTR and better outcomes . However, the evidence level is poor and little research has investigated whether the LTR leads to better outcomes [4, 5].
A study reported found no association between the LTR and pain reduction [9, 10].
The research suggested that the LTR should be not considered necessary for better outcomes . Though most research may show positive outcomes from DN, they usually have a lack of control group, blinding and high evidence. Thus, we cannot say the LTR is necessary for pain reduction or successful treatment .
LTR and post-treatment muscle soreness
All myotherapists have practiced DN on each other’s body to see and feel the LTR. Repetitive fishing or in-and out movements can elicit the LTR and do cause muscle soreness after the treatment. A research showed that pain level during treatment and a number of needle insertion caused post-treatment soreness and hyperalgesia . Thus, this can lead to a downward outcome.
Is DN necessary for musculoskeletal conditions?
Study in 2017 investigated the effectiveness of DN on neck and shoulder pain in comparison with manual therapy (pressure technique with a wooden cone). This study illustrated that both improved pain, neck disability index and muscle characteristics such as stiffness and muscle elasticity with no significant difference between groups .
As the limitations in this study mentioned, there was no control group nor blinded. Therefore, it is hard to draw a conclusion that both DN and manual therapy help reduce neck and upper shoulder pain.
What we know
Although dry needling is not supported for mid-long term effects, immediate to short term effects for pain reduction have been reported with low-moderate evidence [12, 13].
Also, DN seems better than sham needling [12, 13, 14].
Does that increase blood flow, resulting in positive results?
The theory of trigger points is that the motor end plate is hyper-active and a lack of energy . Increase in blood flow and oxygen saturation temporarily post-DN has been reported . As we know, blood supply is crucial for healing process. The interruption of blood supply is a cause of avascular/osteonecrosis . A chief reason is why meniscus injury can heal on its own is that 10-25% of meniscus is vascularized, indicating the healing potential . Improvement in blood circulation may help tissue healing if the pain or dysfunction is caused by mechanical issues.
Neurophysiological effect and pain science
DN may induce neurophysiological effects such modulation of dorsal horn activity and the activation of the descending pain inhibitory pathways as well as A and Aβ fibre [3, 6, 15].
Aβ fibre can be activated by non-nociceptive stimuli like rubbing the skin or maybe DN. This fibre is also known as the gate-control theory. When this fibre is activated, GABA, which inhibits or may block pain, is released. The activation of Aβ fibre may stimulate the substantia gelatinosa (SG) at the dorsal horn of the spinal cord to stop conveying nociception to the second order neuron (to interneuron to the brainstem).
Therefore, rubbing and massaging the painful or injured sites is thought to relieve pain temporarily .
These fibres and pathway are linked to central and peripheral sensitisation . Therefore, clinical reasoning to choose DN in this case is not due to a mechanical problem but to potentially to induce a neurophysiological effect.
What we don’t know
What we don’t know is so many things like whether DN really works on pain for short to long-term, how this can improve pain, disability and muscle characteristics, and is superior to other interventions. I have written in the previous blog about a lack of reliability of palpation to detect trigger points, local twitch response and pain referral are not used as diagnostic criteria for myofascial pain syndrome as they are not well-researched as well as ambiguous .
Understanding pain science, patients and research evidence help clinical reasoning and a choice of interventions. If a patient is not keen to get a muscle soreness or pain, we might choose to leave needles rather than fishing or rotating. If a patient is a massive believer of DN, we are likely to use it but not necessary to elicit the LTR. It is vital for practitioners to know a patient’s belief about pain and DN. Positive effects we can possibly get from DN may be obtained by different interventions.
Like the conclusion of most research, more studies are needed to be investigated further.
Double blinding may be used to research the effect and mechanism of DN to reduce biases and for more high-quality research .
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