Electrotherapy

Question 1

Describe the target nerves and parameters for C-TENS.

Answer 1

Target: delta opioid receptors and serotonin AND A-beta&alpha skin afferents to inhibit at the level of the spinal cord via inhibitory interneuron.
80-120/150Hz
150-200micros
As long as needed for pain control
Effect is immediate and lasts 0-20min after cessation

Question 2

Describe the target nerves and parameters for A-TENS.

Answer 2

Target: A-delta and C fibres, alphaMN large diameter,
mu opioid receptors
0-10Hz (ideally 3-5)
250micros
30min application - may be applied every 4 hours
Dull, achey sensation.
Effect takes 20-30min, but lasts 2-24 hours.

Question 3

List the possible placements for TENS electrodes.

Answer 3

i) bracket area of pain
ii) within the same dermatome.
iii) at referred pain locations
iv) on acupuncture points

Question 4

Explain the possible goals of NMES.

Answer 4

i) prevent atrophy
ii) strengthen muscle
iii) develop motor program
iv) spasticity management
v) edema management

Question 5

Describe how motor unit recruitment varies from normal under NMES.

Answer 5

Normally, I - IIa - IIb. Henneman size principle + recruit what is needed for a task. However, under NMES larger diameter axons are easier to recruit first so the order s reversed at IIb - IIa - I. Also recruitment is “all or none” or synchronous rather than asynchronous to allow smooth, coordinated contraction.

Question 6

Describe the relationship between NMES and fatigue.

Answer 6

Higher frequency = higher fatigue level. 20-30Hz is ideal.

Question 7

Describe NMES parameters for muscle strength.

Answer 7

300micros
50Hz
1:5 ration .. 10son:50soff
2s ramp
Amplitude to tolerance level.

Question 8

Describe the NMES parameters for muscle endurance.

Answer 8

300micros
20-30Hz
1:1 ratio
2s ramp
Low amplitude

Question 9

How should electrodes be placed for NMES?

Answer 9

One on the motor point (where the nerve enters the muscle) and another proximal or distal to this along the pathway of the nerve.

Question 10

Explain Russian Current stim.

Answer 10

High frequency (to decrease skin impedance) NMES set at 50pps and 1:1 or 1:50 ratio. 10ms pulse duration and interpulse interval.

Question 11

When can you wean off of NMES?

Answer 11

Pt has good volitional control and has at least gr. III strength.

Question 12

Explain the rationale of IFC (vs regular TENS).

Answer 12

Higher frequency allows:
i) patients greater comfort and tolerance
ii) reaches deeper tissues
iii) prevents habituation
..while still achieving the same effects as low frequency. Each channel is slightly different frequencies meaning that they are out of sync - where they meet it results in an alternating medium current that varies in amplitude AT A LOWER FREQUENCY. Denotated Alternating Modulated Frequency (AMF).

Question 13

What frequency do the channels operate at to be effective for IFC?

Answer 13

One is 4000Hz, the other is commonly set to 4050 or 4100Hz. (This means the AMF would be 50-100Hz respectively).

Question 14

List special contraindications for IFC.

Answer 14

No thoracic application over 50mA (can cause v-fib). Not over the epiphyseal plate of children.

Question 15

Name a special use for IFC.

Answer 15

Pelvic floor retraining - may even be able to achieve tetanus.

Question 16

Describe how HVPC works.

Answer 16

A pulsed MONOPHASIC current of short intensity and high intensity which stimulates BOTH sensory and motor nerves. This allows for high PEAK voltage but low OVERALL voltage. They are applied in “twin pulses” at 50-100micros and 150-500volts. Note there is very long interpulse duration to allow high voltage to dissipate. High frequency allows improved PUNCH of materials in and out.

Question 17

Describe the effects of HVPC.

Answer 17

i) increased circulation
ii) increased lymph/immune cells to the area
iii) re-establish normal electrical potential
iv) brings FIBROBLASTS in proliferative healing stage.
MAINLY USED FOR WOUNDS.

Question 18

What is the safe range for application of current?

Answer 18

o.1-0.3mA/cm^2 electrode.

Question 19

Name a special contraindication for HVPC.

Answer 19

Acute inflammation - do not want to add energy to injury.

Question 20

What are the parameters for HVPC?

Answer 20

60 - 125 pps
40-100 micros
150-200v
45-60min 3-5X/week.
SAME AS TENS FOR PAIN.
50-20Hz edema reduction
25-65Hz muscle stim.

Question 21

Describe the unique effects of cathode and anode in HVPC.

Answer 21

Cathode:
i) attracts fibroblasts
ii) attracts leukocytes
iii) BACTERICIDAL
iv) reduces edema, increase blood flow
v) epidermal cell migration.
Anode:
i) attracts neutrophils (active)
ii) inhibits mast cells
iii) BACTERICIDAL
iv) clotting 
START W/ CATHODE ON WOUND THEN SWITCH. REVERSE WEEKLY OR WHEN PLATEAUED.

Question 22

Describe how iontophoresis works.

Answer 22

The use of current by electrodes to facilitate administration of topical medications (water soluble). Drug is put under electrode w/ same polarity so it is “repelled” into the tissue. Requires 40mA/min (ex. 2mA for 20min). TYPE OF DIRECT CURRENT.

Question 23

Name to special conditions in which iontophoresis is indicated.

Answer 23

Hypertrophic scars and myositis ossificans.

Question 24

Name a special contraindication for iontophoresis.

Answer 24

elderly and children.

Question 25

Explain the difference in how the cathode (-ve) and anode (+ve) affect tissues in monophasic current.

Answer 25

Cathode: softening of tissues (alkalotic)
accumulate water
depolarize
Anode: hardening of tissues (acidic)
deplete water
hyperpolarize (reduce excitability)

Question 26

Define a direct current and contrast that with a pulsed monophasic current.

Answer 26

Direct: current flows in one direction for at least 1s

Pulsed monophasic: ‘’ for less than 1s

Question 27

List the uses for direct current.

Answer 27

i) iontophoresis
ii) wound healing
iii) hyperhydrosis
iv) edema
v) muscle activation
vi) pain

Question 28

Explain how diadynamic current works. Name one special consideration/precaution.

Answer 28

Alternating current modified to flow as half ine waves in one direction - therefore monophasic. It is used for analgesia, however due to monophasic nature and increased risk of chemical burn - 10min max Tx. Range 4-10mA.

Question 29

Explain how microcurrent works.

Answer 29

<1mA direct or monophasic pulsed current. 50% duty cycle. 500micros pulse duration. Subsensory, used for wound healing. Although can get garments for pain relief as well.

Question 30

Explain the mechanism and usage of short wave diathermy.

Answer 30

An electromagnetic modality 27.12 MHz alternating current. (coil, drum etc.). Used for pain, tone, contracture, chronic inflammation. Targets nerves, collagen and blood vessels. high power = thermal effect, low power = athermal effect. Impoertantly, can heat tissues AT ANY DEPTH.

Question 31

Describe the special considerations in the application of shortwave diathermy.

Answer 31

i) electrode must be larger than limb diameter.
ii) electrodes must be parallel to surface.
iii) electrodes must be spaced further than the sum of the electrode to skin difference under each electrode - otherwise they will just pass between each other.
iv) remove ALL metal.
v) measured by min, mild, mod, heat
vi) decrease intensity w/ severity of swelling
NOT OVER EPIPHYSEAL PLATES IN CHILDREN.

Question 32

Describe how shockwave therapy works.

Answer 32

Pulsed as compressed air causes projectile to collide with the transmitter which creates an acoustic wave that is applied to the tissue through US gel. Basically super ultrasound. Used to treat connective tissue. Can be i) focused (30cm deep) or ii) radial (7cm). Parameters include pressure/intensity (bar), # total hits, frequency (Hz), and size of transmitter.

Question 33

What are the indications for laser therapy?

Answer 33

i) pain
ii) chronic inflammation
iii) scar tissue and fibrosis
iv) acute soft tissue injury
v) open wounds

Question 34

How are lasers different from ordinary light?

Answer 34

i) monochromaticity: all one colour (one wavelength)
ii) collimation: all rays are parallel, no divergence
iii) coherence: all rays have same frequency and phase (peaks and troughs line up - or spatial and temporal coherence).
Note: LEDs often used as well. Only monochromatic. Lower power.

Question 35

What are the two types of lasers commonly used in physical therapy?

Answer 35

Red Waeband (HeNe)
Near Infrared Waveband (Gallium Arsenide)

Question 36

Explain how laser therapy works.

Answer 36

Chromophores (especially found in melanin and Hb) in the skin absorb certain wavelengths and reflect others. The wavelengths absorbed cause activation of that cell. NOTE: low frequency (long wavelength) means it will penetrate to deeper tissue. Promotes healing, blood flow, energy synthesis, nerve regeneration, collagen synthesis. Affected by fat content and melanin,

Question 37

Describe the special contraindication of laser therapy as well as they safety considerations.

Answer 37

i) malignancy (avoid moles)
ii) pt on immunosupressant medication

i) eye wear for you AND the patient
ii) warning sign in area
iii) clear and controlled area
iv) close doors

Question 38

Briefly explain UV therapy.

Answer 38

Used for skin conditions. Apparently dosed in %s?