A hand held point stimulator device is a very useful tool which may be used when needling in the treatment of musculoskeletal pain syndromes - mainly for the deactivation of trigger points (TrP). It may be tolerated better with less treatment soreness as opposed to a more conventional dry needling technique, this is certainly the case from my own clinical experience with the device. The lack of evidence for efficacy is due to the fact that to my knowledge no trials have been performed to date, however we may be guided by the current evidence we have supporting the use of needling for myofascial pain syndrome for example. Clinically we have very good evidence to suggest a handheld point stimulator is an extremely effective way of comfortably augmenting the needle effect.
Is a versatile hand held electro-stimulatory device and can also be used to locate areas of decreased skin resistance thought to correspond with traditional acupuncture points.
Device features are as follows
- Runs off 9V battery
- Delivers square biphasic wave, with a pulse width of 260uS
- Intensity range of 0-45 milli-amperes
- Stimulatory frequency range from 1-16 Hz, 8 Hz usually most comfortable - see the digital display for frequency being used
- The polarity is generally kept at ‘+’
- When used for direct needle stimulation, the sensitivity knob to is kept to ‘0’ otherwise when touching the needle the device will beep and the green pilot light will blink
- Turning up intensity dial is between the blue and black zones
- Blue zone labelled 0-2, equivalent to 0-2 mA
- Black zone labelled 2-10, equivalent to 2-45 mA
It is important to maintain contact with skin with the therapist's other hand during treatment to complete electrical circuit (or patient hold ground pole) - when holding the device the therapist must make contact with one of the metal surfaces. If a tingling in the fingers on metal surface is felt, this is interpreted as the intensity is turned up too high
When using the device it is important to apply general EA safety concerns which include the following:
- Avoid the area of carotid sinus
- Avoid the anterior neck and precordial areas
- If the patient has a pacemaker- avoid the anterior chest area
- Do not use if has patient has an ICD
Always start with low intensity, avoiding strong uncomfortable contractions. It is important to use care if stimulating near neurovascular bundles to avoid strong contraction of all muscles innervated by that nerve. In this case it is recommended to use very low intensity and frequency of 1 so that treatment can be stopped if over-stimulation of a motor nerve occurs.
Locating Trigger Points
Identify TrP's and taut bands based on currently accepted diagnostic criteria and needle into or over the TrP directly.
- Diagnostic criteria include
- Palpable taut band
- Exquisite tender point with referred pain on moderate compression for 4-5 secs
- Characteristic referral patterns
- Active/ latent?
- Jump sign
- Local twitch response
- Autonomic phenomena
On basis that up to 85-90% of TCM acupoints are likely to correspond with TrP and that TCM acupoints show lowered areas of skin resistance - use the device sensory mode to locate areas of decreased skin decreased/ acupoints. Insertion of the needle and stimulation at this point is likely to correspond with that of a TrP associated with a dysfunctional motor point. If the acupoint does not coincide with the TrP, it is likely to be nearby and the TrP should be needled directly.
Use of device for treatment of TrP
- Touch needle or the metal handle with the probe of device with other hand in contact with the patient's skin in the vicinity of area being treated
- Stimulation is maintained for up to 1-3 min, at 2-10 second bursts with comfortable muscle contraction, 5 seconds rests between
- If the needle is properly inserted at a TrP/ taut band a strong painless contraction should be achieved in blue zone/ 0-2mA range
- Palpate for relaxation of the taut band and reduced resistance to the tip of the needle lift and re-insertion during and after treatment
- Stimulation of a TrP will usually also reproduce familiar and tolerable pain with the contraction, if pain is reproduced but not contraction it is possible the nociception may be coming from non contractile tissue eg ligament, tendon or joint capsule
Alternate method - Use of the device followed by multi-point electroacupuncture
- Identify the TrP/s using procedure 1 or 2
- Connect one lead of an EA device to the needle inserted into the TrP and the other lead into an adjacent point (ideally within the taut band/ along the length of the muscle belly)
- Stimulate at a strong but comfortable intensity, usually at 2 hz
- Note: if the needle is inserted near a cutaneous nerve the skin A-delta pain fibres will depolarise which is not comfortable for patient, remove and re-insert needle
- Activation of intramuscular type 11/111 (but not type IV) muscle afferents as well as type 1a or 1b muscle ergoreceptors (proprioceptors sensitive to muscle stretch and contraction) found in the vicinity of the motor end plates
- Triggers local, segmental, extra-segmental and central regulatory effects which include pain modulation/analgesia
- Achieved with strong yet non painful stimulation
- Lower intensity EA is less likely to stimulate the A Beta or A Delta fibres in the skin, optimising the treatment effect while keeping the stimulation comfortable for the patient
- Use EA to enhance segmental and extrasegmental effects
- Activation and depolarisation of the motor nerves will elicit a muscle contraction
- Mechanical effects may disrupt the dysfunctional motor end plate which may play a role in the development and persistence of the myofascial TrP
Use for diagnostic/ functional anatomy purposes
The device may also be used to confirm the correct needling of intended muscles found to be dysfunctional or pain sensitive on assessment. In this case use low frequency 1-2 Hz and observe/palpate the muscle activity as well as tendon movement. For deeper muscles it may only be possible to observe needle movement for example when needling piriformis or multifidus.
Style Acupuncture in Portugal. Acupunct Relat Ther 2014;2:19–24.
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