Transcutaneous Electrical Nerve Stimulation TENS

Question 1

What is Tens

Answer 1

TENS is a method of electrical stimulation which offers symptomatic pain relief by exciting sensory nerves and stimulating either the pain gate mechanism and/or the opioid system.

The different methods of applying TENS relate to these different physiological mechanisms.

Question 2

Mechanisms of action

What is the aim of TENS stimulation

Answer 2

Stimulate sensory nerves and activate specific natural pain relief mechanisms

Question 3

Mechanisms of action

What are the two primary pain relief mechanisms that TENs
activate

Answer 3

1) Pain gate mechanism

2) endogenous opioid system

Question 4

Mechanisms of action

What do you stimulate to excite the pain gate mechanism

Answer 4

1. AB fibres

Question 5

Mechanisms of action

What do you stimulate to excite the opiod mechanism

Answer 5

2. Ad fibres

Question 6

Mechanisms of action

What happens when you excite AB and AD fibres

Answer 6

Stimulates pain gate and opiod mechanisms

Stimulating both nerve types at the same time by using a burst mode of stimulation

The higher frequency stimulation 100 HZ is interrupted/burst at the rate 2–3 bursts per second

Question 7

Mechanisms of action

1)What does pain relief by the Pain Gate mechanism involve?

Answer 7

Activation of a AB sensory fibres which reduce transmission of noxious stimulus from the C fibres through the spinal-cord and onto higher centres.

Question 8

Mechanisms of action

How do the AB fibres like to be stimulated

Answer 8

High rate 90-130 Hz or pps

Not a single frequency works best for every patient this range covers majority of individuals

Clinically we need to find the patient optimal treatment frequency which will vary between individuals

Question 9

Mechanisms of action

2)What is an alternative approach via the Pain Gate mechanism

Answer 9

Stimulate AD fibres which prefer a lower rate of stimulation 2-5Hz

Question 10

Mechanisms of action

What rate of stimulation do AD fibres respond to

Answer 10

2-5Hz

Question 11

Mechanisms of action

What does stimulating AD fibres do

Answer 11

Activate the opiate mechanisms and provide pain relief by releasing an endogenous opiate ENCEPHALIN in the spinal-cord which reduces the activation of noxious sensory pathways

Unlikely one frequency works for all patient need to explore options where possible

Question 12

Mechanisms of action

Where is ENCEPHALIN released and what does it do

Answer 12

Spinal cord which reduces the activation of noxious sensory pathways

Question 13

Mechanisms of action

What do the bursts cause

Answer 13

The bursts activate a AB fibres and the pain gate mechanism the burst will produce excitation in AD fibre is stimulating the opioid mechanisms

Question 14

Mechanisms of action

Which is the most affected of the 3vpain gate mechanisms

Answer 14

AB+AD

For some patients this is the most effective approach to pain relief some patients find the sensation less acceptable than other forms of TENs

Question 15

Types of TENs output

Answer 15

1. Traditional normal high frequency TENs
2. Acupuncture like TENs AL TENs low frequency
3. Brief intense
4. Burst load
5. Modulation mode

Question 16

1. Traditional normal high frequency TENs

Answer 16

Useful for treating acute pain

Stimulation at a high-frequency 90-130Hz short duration pulses approx 100ms

Stimulation delivered at ‘normal’ intensity patient should feel tingling but not uncomfortable

Length= 30 minutes main pain relief is (minimal effective time)
Can Be delivered as long as needed main pain relief is achieved during the simulation with a limited carry over a fact – pain relief after machine is switched off

Useful technique – short-term pain relief which enables patients to comply with treatment

Question 17

2. Acupuncture like TENs AL TENs low frequency

Answer 17

Useful for treating chronic pain

Uses lower frequency 2-5Hz with longer pulses 200-250ms intensity will usually need to be greater than traditional TENS still not at patients threshold but a strong tingling sensation

Length = 30 minutes delivered as a minimal dose affect

I’ll be at levels take time to build up with this type hence onset of pain relief may be slower than traditional

Once there is a sufficient level of Opiod level reached it will keep working after stimulation

Patient find stimulation of low frequency intervals throughout the day is affective

Carryover affect may last several hours carryover will vary between patients

Question 18

3. Brief intense

Answer 18

Useful for achieving rapid pain relief

some patients may find strength of stimulation to be intense and cannot tolerate it for sufficient duration it make it worthwhile

High frequency 90-130Hz pulse duration is high 200ms+

Current level is close to threshold for patient and they would not want it turned up any higher energy is high compared to other approaches

Length = 15–30 minutes

Question 19

4. Burst load

Answer 19

Effective pain relief but not always tolerable

Traditional TENS but push mode is switched on which interrupts stimulation outflow at a rate of 2–3 bursts/s

Stimulation intensity will be high similar to acupuncture TENS

The burst mode can effectively stimulate both pain gate and opioid mechanisms simultaneously

Question 20

5. Modulation mode

Answer 20

Machine delivers less regular pattern off TENS stimulation to reduce or minimise accommodation affects of regular stimulation

Machines offer different methods of varying stimulation pattern:

Varying intensity
Varying frequency
Varying prostration

Some machines offer a choice between methods research does not favour one variation over another

Most useful for patients who use TENs a few hours a day

Question 21

Frequency selection

Answer 21

It is inappropriate to identify very specific frequencies to achieve an effect

Not one frequency works for everyone

Therapist need to identify efficient frequency for the individual patient and their pain

Best way to do this is the patient adjusting frequency dial

Question 22

Stimulation intensity

Answer 22

Like frequency selection it is not the same intensity for all

Most effective intensity management is letting the patient choose and try different simulations this may vary from session to session

Question 23

Stimulation intensity

General rule for Normal and acupuncture

Answer 23

normal high-frequency TENS :
‘definitely there but not painful level’

acupuncture low-frequency TENs:
strong but not painful level

Question 24

Selection/placement of electrodes

Answer 24

Most machines offer a dual channel output:

X2 pairs Of latitude can be used simultaneously which can achieve advantages most therapists use a single channel

Widespread and I diffuse pain presentations can be treated with a 4 electrode X2 channel system and I combined treatment for local and referred pain

Question 25

Selection/placement of electrodes How do you get maximum benefit from modality (Spinal cord)

Answer 25

Target the stimulus at appropriate spinal-cord level (appropriate to pain) Placing electrodes either side of lesion or pain areas is the most common mechanism used

Question 26

Selection/placement of electrodes How do you get maximum benefit from modality (Nerves)

Answer 26

Stimulation of appropriate nerve roots Stimulate the peripheral nerve (proximal to pian) Stimulate trigger points or acupuncture points Stimulate the appropriate dermatome/myotome

Question 27

Selection/placement of electrodes What do you do if pain source is vague/diffuse/extensive

Answer 27

Both channels can be employed simultaneously A 2 channel application can be effective for management of a local and a referred pain combination - 1 channel used for each component