Transcutaneous electrical stim (TENS)

Question 1

what is TENS

Answer 1

is a method of electrical stimulation whereby low frequency electrical currents are applied to the skin via leads, and surface electrodes, stimulating sensory nerves, principally for the symptomatic relief of pain

Question 2

clinical use of TENS- success not guaranteed

Answer 2

acute pain joint pains, LBP, neurogenic pain, post-op pain, obstetric pain- during labour, chronic pain, arthritic condition- RhA

Question 3

advantages and disadvantage of TENS for pain control

Answer 3

advantages- non-invasive, few side effects, patient controlled, battery operated and portable
disadvantages- allergic skin condition (electrode material, conductive gel, tape to hold electors in place), short lived relief, same as control

Question 4

what does the biphasic nature mean

Answer 4

the biphasic nature of the pulse means that there is no electrolyte built up under the electrodies, thus minimising skin reactions

Question 5

TENS labelled

Answer 5

intensity, pulse with, pulse rate, different modes- burst, Normal, modulated- in between, stronger sensation=more stimulus= reduces pain

Question 6

dual channel machines (4 pads)

Answer 6

2 pairs of electrodes, applied simultaneously,useful for widespread and diffuse pain, intensity is set separately for each channel, other parameters selected cover both channel

Question 7

parameters of TENS

Answer 7

current intensity (strength)- 0-80mA, pulse frequency (rate- 2-250Hz), pulse width (duration- 50-250us), intensity controls- sufficient to depolarize sensory nerves.

Question 8

different modes of TENS

Answer 8

burst mode- pulses are produced in bursts or trains usually at a rate of 2-3 bursts per sec- stimulates both nerve types (AB and AD, good for opioid mechanisms), modulation- less regular pulse outputs, minimising accommodation

Question 9

pathological effects of TENS

Answer 9

aims to excite sensory nerves thereby activating specific natural pain relief mechanism, can influence pain gate mechanisms- stimulates AB fibres- produces reduction in transmission of nociceptive fibres (80-120Hz) and endogenous opioid system

Question 10

mechanisms of action- endogenous opioid system

Answer 10

release of endogenous opiates, stimulation of AD fibres causes release of encephalin in the interneurons of the posterior horn of the spinal cord and in the midbrain. encephalin inhibits the C fibres system and reduces the activation of noxious sensory pathways. AD fibres respond to 2.5Hx

Question 11

Conventional/ normal TENS

Answer 11

high frequency- 80-130Hz, narrow pulse width, 30 mins minimum effective time, as long as needed, pain relief during stimulation
AB fibres- pain gate activation- 90-130Hz

Question 12

acupuncture/ low TENS

Answer 12

low frequency 2-5Hz, wider (longer pulse width), strong intensity- not at patient threshold, 30 mins treatment is minimally effective dose, apply at intervals throughout the day, carry over several hours

Question 13

Burst TENS

Answer 13

high frequency- 90-130Hz, narrow pulse width, relatively high intensity, a series of pulses repeated 2-3 times per sec, stimulates both pain gate and opioid mechanism

Question 14

modulated TENS

Answer 14

delivers irregular bursts of stimulation, reducing accommodation,

Question 15

brief intense TENS

Answer 15

for rapid pain relief, pulse frequency high (80-130Hz), pulse width is high, intensity is close to tolerance level, energy delivered high, 15-30 mins

Question 16

frequency selection

Answer 16

no single frequency works for everyone, patient and therapist need to identify the most effective frequency for pain relief, manipulare stimulation frequency dial or button to achieve this

Question 17

electrode placement

Answer 17

machines may be single or dual channel, position electrodes to stimulate the sensory nerves which enter the spinal cord at the same level- dermatomes, myotomes, sclerotomes, motor points, nerve root, peripheral nerve/trunk, trigger point

Question 18

contraindications

Answer 18

patients who do not comprescence the physio instructions or who are unable to cooperate, patient with pacemakers, skin allergies to electrodes, gel or tape, dermatological donations- dermatitis, broken skin, eczema, area of tumor or suspected malignancy, abnormal sensation, current/ recurrent bleeding, compromised circulation, area of active TB, devitalised skin, epilepsy

Question 19

where not to place electrodes

Answer 19

over trunk/pelvis in first 12 weeks of pregnancy, over pregnant uterus at any stage in pregnancy, over the eyes, epiphyseal regions in children, over anterior neck

Question 20

precautions

Answer 20

abnormal skin sensation- reposition, epilepsy- seek with medical practitioner, abnormal electrodes used in labour may interfere with foetal monitoring

Question 21

hazards

Answer 21

drop in BP, skin irritations, skin burns, electric shocks

Question 22

mandatory

Answer 22

explanation of treatment- ensure understanding, colloquial terminology, informed consent- verbal or written, tests- sharp blunt sensation, questions- contraindications and precautions, warnings- if the patient experiences anything other than the expected sensation, they should inform the physio ASAP

Question 23

prior to each application

Answer 23

visual checks of the electrodes, functional output of the unit, leads and electrodes is tested, the patient is positioned comfortably, with adequate support, the area to be treated is exposed, the skin is cleaned

Question 24

application

Answer 24

if using aqueous gel, the gel is applied to the skin uniformly, once the electrodes are applied the current is switched on and increasing slowly, the unit is switched off prior to removal of the electrodes, patients are advised never to use TENS whilst driving or operating machinery