Basic (basic) neuroanatomy Mechanisms of stimulation/modulation Procedures and application

(Part 2) The practical application of electroacupuncture

Basic, basic concept of neuroanatomy

1. Large diameter nerve fibres (group II) - sensory group

(2. Motor neurons ie, movement)

3. Small diameter nerve fibres (groups III and IV and are associated with pain)

- other sensation + ‘pain’

Three types of neuromodulation: (this is how we effect sensory, motor, other sensation/pain)

Physiological blocking effect- reduces the conduction velocity

Segmental inhibition / gate control- Stimulation of large diameter group II fibres can reduce the perception

of pain Comfortable paraesthesia with no contraction Analgesia primarily by spinal segmental mechanisms i.e. gating

effects + RAPID onset

Supraspinal/opioid release (next slide)

Supraspinal / opioid release (Slow build-up to maximum)- Stimulation of opiates (endorphins)

Enkephalin (binds to morphine receptors) Beta-endorphin Dynorphin (200 x morphine, 50 x βendorphin)

Endorphins work in the presence of substance P

Should produce visible muscle contraction (over the myotome related to the painful area)

Patient will experience paresthesia and muscle contraction (which may not be visible)

Operates primarily through the descending pain suppression system - thus relatively longer onset to analgesia but it lasts longer (activates neurochemicals?)

Hence:

First the patient will report sensory (group II fibre sensation) of paraesthesia

Motor fibres are recruited next causing contraction

Finally, nociceptor (group III and IV) to evoke pain(Sharp pain first, followed later by burning/aching pain later)

What does this basic neuromodulation and anatomy mean in a real clinical context?

Movie of settings

Neuromodulation has a relationship with frequency!

Use at appropriate nerve endings, dermatomes, spinal segments, relevant local areas or acupuncture points

Low frequencies (eg 2 Hz) will stimulate release of: endorphins in the brain large amounts enkephalins in the spinal cord (brain?)

High frequencies (eg 100Hz) will stimulate release of: large amounts of dynorphins in the spinal cord

Thus it is assumed that mid range (eg 15(?)) may release a small amount of enkephalin and dynorphins

One further influencing factor

Impedance (AC) decreases as needle depth increases and muscle is more conductive than fat.

Depth (mm)

1 2 5 10 20 30 40 50

Impedance (Ω)

3.5K 1K 788 635 538 486 466 450

This means make sure the needle is stuck in OR if using a pad, then make sure amplitude is enough to activate the target structure! Less needed if using needle electrode More needed if using a pad electrode

Devices

(Examples of devices in the UK market)A. Classic 4 (HMD Europe, UK); B. AS Super 4 (Schwa-Medico, Germany); C. V-TENS Plus (BodyClock, China); D. ES160 (Ito, Japan); E. E600 HAN (TENS Plus, Hong Kong, China). (Ref: Figure 6 compiled from David Mayor)

BA C

D E

General Guides

Use EA (acupoints) in exactly the same way and on the same points as normal acupuncture Particularly useful for scalp acupuncture

Just remember to use the right frequencies and adjust intensities appropriately to desired effect

Knee EADense Disperse2Hz/100HzArthiritis, overuse, degenerative changes, post-acute

Same as EA only difference is pads, and not needles. Amplitude/intensity also higher in comparison to EA

Ensure the operational safety of the equipment (technically checked)

Inspect leads/clips for damage

Caution is to be exercised in patients with

Contraindications ALWAYS CHECKED

Precautions ALWAYS considered A lack of skin sensitivity Arterial disease (HBP) and DVT Skin conditions Others…

ON/OFF sequence is vitally important

make sure that all intensity dials are set to “0” and the machine is OFF before connecting the cables.

When switching the device off, dial the intensity down to “0” first, then switch the machine OFF.

Application and Procedure

Make sure to have the ‘TENS/EA’ switch on correct setting

Remember your needle depth to impedance relationship and take into account the needle has to be physically capable of supporting the lead

Position the clip low on the shaft/handle (but not touching the skin) – the weight of the clip can pull the needle out (Tape on the lead or the needle)

For virtually all current models of EA device, the relationship between the dial setting on a device and the amplitude of stimulation is not linear. Similar increments of intensity do not increase the amplitude by equivalent amounts (you don’t want to hurt your patient)

remind the patient of the sensations that will be felt before proceeding – you should have already obtained “informed consent” prior to initiating the process!

After setting the correct frequencies, carefully and slowly increase the intensity, seeking feedback from the patient as you go.

Using a dense/disperse wave, increases in amplitude will be more stronger but comfortable for a patient - increase during the ‘stronger’ sensation (often when “high” frequency phase when current intensity is strongest but this can vary between individuals and within same individual )

Patient response will be one of heaviness or aching (other words used to describe de qi)

Muscle twitch/contraction is common (and at times wanted)

Pain response – no beneficial therapeutic effect

General Rule: the sensation should between the sensory threshold and pain threshold: Sensory threshold – numb sensation

Motor or movement Strong but comfortable

Pain threshold – uncomfortable, painful – varies from person to person

The interval between the two may be narrow and needs to be carefully adjusted

The patient will likely not tolerate intensity above the ‘pain’ threshold – mild moderate or ‘strong but comfortable’ recommended as maximum strength.

Remember sensitisation, which means you will have to adjust the intensity throughout the treatment or leave instructions with your patient on how to adjust the intensity

Ensure sufficient needle depth (electrode placement)

Some examples of applciations

Connect the two electrodes to the same point bilaterally eg. one lead on SP6 (L), one lead on SP6 (R) (you won’t know which one will feel strongest to the patient and swapping the leads will not make any difference)

Connect one lead to one point, and the other to any other point near by (or a reference electrode)

Connect two needles within the same dermatome (limb channels follow generally the dermatomes)

EA @ Sp 6 (Sanyinjiao) & GB 37 (Guang Ming) Dense Disperse 2Hz/100HzPeripheral neuropathy

Use the insertion and origin points of a muscle (be careful of the tendon)

Use any two points within a particular muscle

Needling with electro to treat for the right side tibialis posterior (image taken looking down to the right medial lower leg, the EA device propped on the inside left leg)

Needle on either side of the dorsal horn as well as the peripheral/distal site of the nerve pathway to engage the gating mechanism

Thus: Nerve root/dermatome Point proximal to pain Point of pain Point distal to pain

Placement of electrodes for the Lower Back (example of classic acupuncture and channels merged with neuroanatomy)

Bl10 (needle only: upper meeting point) Associated nerve roots/dermatome (Back shu points) (EA) Involved muscle in the gluteal region (EA) Bl 40 (needle only: lower meeting point)

Surround needle a lump/mass/lesion and pass the current through the lump

(In this instance, be wary of malignant or neoplastic masses as opposed to benign masses such as bursas, lipoma etc)

Thank you for your time today