Electrical Currents for Pain Control

Lecture 6

SUBJECTIVE, not always tissue damage

What is pain?

nociceptive, neuropathic, somatoform

the three types of pain are _____, ______, and _____

Nociceptive

______ pain is stimulation of nerve fibers that respond to stimuli approaching or exceeding harmful intensity

Thermal, Mechanical, Chemical

Nociceptive pain can be _____, _____, or ______

nociceptive

Visceral pain is a type of ______ pain described as diffuse and dull, hard to locate

nociceptive

Deep somatic pain is a type of ______ pain typically in joints, tendons, or ligaments but the patient can’t usually pinpoint

nociceptive

Superficial Somatic pain is a type of _____ pain described as easy to locate typically found with burns

Neuropathic

_______ pain is described as “Burning, tingling, electrical, stabbing, pins & needles” or phantom limb pain and neuropathy

Somatoform

______ pain, also called psychogenic, is described as pain caused, increased, or prolonged by mental, emotional, or behavioral factors

Acute Pain

________ typically needs medial, pharmacologic, and rehab care (warning system and expectation of resolution)

Chronic

______ is less defined with no biologic benefit and is often pain that persists beyond the normal time of healing

F; only takes 3 months

T/F: it takes 6 months to determine if pain has switched to chronic state

A-alpha fibers, 80-120

_______ are myelinated fibers that carry proprioception info at ______m/s with a diameter of 13-20 micrometers

A-beta fibers, 35-90

______ are myelinated fibers that carry touch info at _____m/s with a diameter of 6-12 micrometers

A-delta fibers, 5-40

______ are myelinated fibers that carry pain (mech & thermal) info at _____m/s with a diameter of 1-5 micrometers

C fibers, 0.5-2

______ are non-myelinated fibers that carry pain (mech, thermal, and chem) info at _____m/s with a diameter of 0.2-1.5 micrometers

F; A-beta are faster with conduction speed of 35-90 m/s

T/F: C fibers conduct faster than A-beta fibers

C

All of the following are myelinated fibers EXCEPT:

• A-alpha

• A-beta

• A-delta

• C

Ascending, dorsal

_____ nociceptive pathways are for sensory and afferent info through the ______ root

Descending, ventral

______ nociceptive pathways are for motor and efferent info through the _____ root

A-delta, C

the ascending nociceptive pathway includes Fast and Slow fibers: _____ fibers and _____ fibers

fast and well-localized, withdrawal reflex

Myelinated A-delta fibers assist in _______ pain or ______ like touching a hot object

slow transmission/longer lasting

Non-myelinated C fibers assist in _______ pain also described as diffuse dull pain

• fun fact: this accounts for 70% of all nociceptive pain

CNS, top-down

Motor/efferent info starts in the ______ and diminishes the ascending signals via a ______ mechanism

opinion

Pain is not a reflexive response, it is an ______

Gate Control Theory

_______ of pain has 3 gates (spinal cord, brainstem, and prefrontal cortex)

• one gate gets closed and makes it harder for pain signal to get through to the other two

• may be ascending or descending

A-beta, inhibitory interneurons

E-Stim is the activation of ______ nerves and can also close a gate by activating _______ in the spinal cord

Endorphins

________ help to modulate the pain gates in the spinal cord

• bind to opioid receptors

• released during exercise and laughter

Black Torpedo Fish

Back in older times, the ________ was used to treat conditions like gout and headaches

1965

After _____, TENS became more popular because it was a non-pharmacalogical option for pain relief 

Transcutaneous Electrical Nerve Stimulation

TENS stands for __________

TENS

the purpose of ______ is to reduce acute, chronic or post op

pulsed biphasic (sym or asym)

the most common waveform used with TENS is __________

conventional/high rate, low rate, burst mode, brief intense

the four types of TENS are: _________, _________, _________, and ________

Conventional, Gate Control, A-beta

_______ TENS is used for sensory level estim ONLY via the ______theory of pain which blocks pain by stimulating the ______ fibers 

high, low, short 

with conventional TENS, use a ____ frequency, ____ intensity, and ____ pulse duration — goal is ONLY SENSORY level 

Sensory-only effect — WE ARE NOT LOOKING FOR A MOTOR RESPONSE/TWITCH

the goal of conventional TENS is

F; very short term effect, maybe 2-3 hrs or during treatment

T/F: with conventional TENS, the pain relief/treatment effect occurs for 4-5 hours after

F; place electrodes on or around sites of pain or even over the nerve innervation (motor points don’t matter as much with TENS) 

T/F: with TENS, you must place electrodes over motor point and avoid painful areas 

A-beta

Conventional TENS works to block pain which is transported by ______ nerve fibers

Conventional 

Parameters for ________ TENS:

• F = 80-150 Hz/pps

• PD = 50-100 microsec

• On:Off Time = continuous 

• I/A = strongest, comfortable paresthesia (no motor response) 

• Tx Time = 15-20 min 

• Effect Time = 2-3 hrs MAX, primarily DURING tx 

• Modulation = maybe use it if it’s available (start with Amplitude first) 

Low Rate

_____ TENS is also called acupuncture-like TENS

opioid release 

Low Rate TENS is based on endogenous __________ of endorphins that bind to opioid receptors in the descending pathways 

motor response (twitch NOT tetani) 

Low Rate TENS requires a _______ by working with A-beta and A-alpha nerve fibers 

low, high, long

For Low Rate TENS, do a _____ frequency, _____ intensity, and _____ pulse duration — this will have a longer/slower start, so give it a few minutes to take effect 

True! this will help to increase the blood flow to that area and mechanically loosen the tissue —> MUST follow up with stretching new loosened tissue to use new ROM

T/F: Low Rate TENS can be used for trigger points or any area where muscle tension is present

True

T/F: for Low Rate TENS, the electrodes should be placed on trigger points or areas of muscle tension

F; give it 5-10 minutes for patient to feel it

T/F: Low rate takes a very short time to kick in

Low Rate

Parameters for ____ TENS:

• F = < 10 Hz/pps 

• PD = 200-300 microsec

• On:Off Time = continuous 

• I/A = Rhythmic muscle twitches (NOT tetani) 

• Tx Time = 20-30 min (MAX is <45) 

• Effect Time = 4-5 hrs 

• Modulation = Frequency!!

A-delta, Natural Endorphin Release

Low Rate TENS will sometimes affect _____ nerve fibers which deal with pain. This could help to amplify the _________ —> this is why the patient MIGHT feel short bouts of pain during treatment

pulse duration 

If your patient cannot increase amplitude, you should change the ________ to increase the motor response 

Low Rate

The goal of _______ TENS is to get patient to 20 min of motor response without making them too sore after tx 

Burst Mode 

if Low Rate TENS is too much for the patient, you should switch them to (conventional/burst mode/brief intense) TENS 

True; still gets motor response but its more comfortable muscle contractions for patient

T/F: Burst mode is a combo of Conventional and Low Rate

Burst Mode

Parameters for ________ TENS:

• F = 100 Hz/pps, delivered at 2 Hz

• PD = 150-200 microsec

• On:Off Time = continuous 

• I/A = Rhythmic muscle twitches (NOT tetani) 

• Tx Time = 20-30 min (MAX is <45…avoid DOMS) 

• Effect Time = 4-5 hrs 

• Modulation = not usually possible

False

T/F: Burst mode is more effective than Low Rate

high, low, long 

For burst mode, use ____ frequency bursts/trains of pulses delivered at ___ frequency with ____ pulse duration — this will cause more comfortable mms contractions for the patient 

wound debridement, c sections

Brief Intense TENS can be used before ______ and post ______

Brief Intense, Noxious 

_________ TENS is short, local hypoalgesia for minor painful procedures at the _____ level 

high, highest tolerable, long 

Brief Intense TENS uses a _____ frequency, ______ amplitude, and____ pulse duration — essentially BEYOND max tolerated 

superficial somatic

What type of nociceptive pain occurs when you cut yourself shaving?

endogenous opioid/endorphin release

what is the mechanism of action with Low rate tens

a-beta for sensory level NOT pain

conventional tens seeks to activate which type of nerve fibers?

a-delta

which type of nerve fiber is the fastest conductor of pain?

low rate 

which type of TENS are you MOST likely to utilize for a trigger point?

75 microseconds

which pulse duration are you MOST likely to use with conventional tens? 

frequency 

which parameter is BEST to modulate with low rate tens? 

conventional/high rate 

which type of tens is BEST for pain control after a recent injury?

F; use high rate

T/F: use low rate and burst mode TENS with inflammation

conventional/high rate 

You should use ____ TENS with your “touchy” patients, aka those who ALWAYS rate their pain 12/10 — they will be able to tolerate sensation but NOT mms contraction

conventional aka high rate 

with a recent injury, you should use (conventional/low rate/burst mode/brief intense) TENS 

FALSE »» use for chronic injuries where there is a longer tx effect and longer duration of pain control 

T/F: low rate tens is used with acute injuries

smaller pads

With TENS on paraspinals, use _____ when there is a specific area of pain or trigger point

larger pads

with TENS on paraspinals, use _____ when there is more diffuse pain

smaller pads

for tens around the knee, use _____ for specified pain like medial compartment

larger pads

for tens around the knee, use _____ for general pain

bony prominences

ALWAYS AVOID _______ but tens is more forgiving about this compared to NMES as tens doesn’t really require motor points 

False!!! TENS only requires rhythmic muscle twitches NOT tetani

T/F: both NMES and TENS focus on max muscle contraction

Modulation

_______ options include:

• M: decrease pulse width 40% for 2”, returns for 3.5” (conventional) 

• SD1: decreases pulse rate 50% for 2”, returns for 7” (low rate, frequency)

• SD2: decrease pulse width 60% for 2”, returns for 3.5” 

DO NOT

For portable TENS and chattanooga machines, you (do/do not) cross the channels when placing electrodes around the area of pain 

1. is pt appropriate for tx 

2. clean skin and remove excess hair

3. connect leads to unit and electrodes 

4. securely place electrodes 

5. adjust parameters

6. slowly increase amplitude (take till pt feels sensation, then keep going till pt says too painful, then back down a little) 

7. gently remove electrodes and assess skin condition 

8. pt education (if home unit, wear times/parameters/placement and care of electrodes/skin care/batteries) 

APPLICATION OF TENS (just read thru…its a lot and you know this) 

120 pps, 75 microsec 

which of the following settings is the MOST appropriate for conventional tens? 

• 4 pps, 200 microsec

• 120 pps, 75 microsec 

• 4 pps, 75 microsec 

• 120 pps, 200 microsec

thought to relieve pain based on the gate control theory (endogenous opioid release!!!)

which of the following statements is MOST true about low rate TENS? 

• pulse frequency should be between 10 and 20 pps

• thought to relieve pain based on the gate control theory 

• treatment time should be no longer than 45-60 minutes

• amplitude should be increased until mms contraction occurs 

IT DEPENDS :) hehe 

• think about goal, amt. of pain, schedule for rest of day

when is it MOST appropriate to use TENS application, before or after tx?

Interferential Current

what does IFC stand for

medium frequency

IFC is interference of 2 _________ alternating currents with slightly different frequencies (but same intensities)

1000, 4-5k

IFC can range anywhere from ____ to 10,000 Hz with a midrange at _________ Hz 

IFC 

______ (aka Amplitude Modulated AC) is delivered through 2 sets of electrodes from separate channels in the same machine 

FALSE: currents intersect ON the skin 

T/F: with IFC, the alternating currents interfere WITHIN the machine before they’re in contact with the skin 

In Sync/Phase

When IFC currents are ______ there is constructive interference, meaning they line up with each other 

Out of Sync/Phase

When IFC currents are ______ there is destructive interference, meaning they are opposite of each other 

beats

IFC produces “envelopes”/bursts of pulses known as _____

beat frequency 

_________ is the difference between the 2 frequencies also known as the therapeutic effect

• ex: #1 @ 5000 Hz // #2 @ 5100 Hz 

• difference of 100 Hz 

sensory level, motor level 

the MOA for IFC is mainly _____ but can be _____ via gate control theory and opioid mechanism 

True-ish, some research supports this as IFC might reach deeper tissues compared to TENS 

T/F: IFC can improve circulation

80-130

IFC using the gate control theory should be at ______ Hz

2-5

IFC using opioid mechanisms should be at _____ Hz

Sweep, Vector Scan

Two types of modulation for IFC is _____ and ____

Sweep 

_____ is when the machine varies the beat frequency usually in a shape 

• preset or user sets ranges 

• not much evidence 

Vector Scan 

______ alters the amplitude on one or both currents

• like the agitator of the washer (turns one way then turns other way) 

• might be better for larger areas