Electrical Stimulation For Pain Modulation

Question 1

High vs Low Frequency

Answer 1

Low (5 pps or less)
High (50 pps or more)

Question 2

Gate Theory Mechanism

Answer 2

Stimulation of large diameter afferents inhibits the nociceptor responses in the dorsal horn

Question 3

Main Mechanisms

Answer 3

Activation of peripheral opioid receptors
Activation of CNS opioid receptors

Question 4

Fiber Activation and Thresholds

Answer 4

Sensory level: Activates A(alpha) and beta
Goal is three or more times sensory threshold

Motor level: Activates A(alpha), beta, and alpha motor neurons (contractions)
Goal is more than two times motor threshold

Noxious level: Activates A(alpha), A(beta), A(motor neurons) and A(delta)
Goal is more than three times sensory and two times motor

Question 5

Low Frequency Mechanism

Answer 5

Peripheral, SC, and supraspinal effects

Activation of µ-opioid system **
(If on opioid medications treatment will not be as effective)

Uses GABA

Question 6

High Frequency Mechanisms

Answer 6

Peripheral, SC, and supraspinal effects

Activates δ-opioid system**

Uses GABA

Question 7

What does each feel like? (Sensory, Motor, Noxious

Answer 7

Sensory:
High frequency: constant “tingling” sensation, “strong but comfortable”

Motor:
Low frequency: “strong twitch”
High frequency: constant contraction (uncomfortable)
Need on/off times (1:1) if using high frequency

Noxious:
High frequency: constant “strong and uncomfortable”, “Sharp, prickly, stinging” (***not burning)

Question 8

Phase/pulse durations

Answer 8

Generally >150 µsec for all

Question 9

Treatment duration and analgesia duration

Answer 9

Sensory:
Treatment - to fit intervention goal
Analgesia - length of treatment plus some

Motor:
Treatment - 30-40 min (low) 10-15 min (high)
Analgesia - hours

Noxious:
Treatment - 10-20 min
Analgesia - hours

More energy in = longer duration of analgesia

Question 10

Adaptation

Answer 10

Adaptation occurs with constant sensory input
Reduced perception of a sensory level stimulus when experienced for a long period of time (also known as accommodation)
Preventing tolerance critical for full effectiveness

Minimized by modulation of:
Pulse/phase duration
Pulse/phase amplitude
Frequency
Combined (duration and amplitude)

Question 11

Interferential Current (IFC)

Answer 11

Specific type of current used primary for pain modulation
Requires a special machine that delivers IF current
Interference of currents (AC) from 2 channels each with different carrier frequencies (4000–5000 Hz range)
Sum of both is the “beat frequency”

Question 12

Contraindications

Answer 12

Other electronic devices (Pacemaker)
Low back or abdomen of pregnant women
Regions of known or suspected malignancy
Recent radiated tissue
Near/over eyes
Anterior neck
Damaged skin

Question 13

Precautions

Answer 13

Sensory impairments
Chest wall
Active epiphysis
Cognitive/communication impairments
Regenerating nerves