Electrical Stimulation For Pain Modulation Flashcards
High vs Low Frequency
Low (5 pps or less)
High (50 pps or more)
Gate Theory Mechanism
Stimulation of large diameter afferents inhibits the nociceptor responses in the dorsal horn
Main Mechanisms
Activation of peripheral opioid receptors
Activation of CNS opioid receptors
Fiber Activation and Thresholds
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
Low Frequency Mechanism
Peripheral, SC, and supraspinal effects
Activation of µ-opioid system **
(If on opioid medications treatment will not be as effective)
Uses GABA
High Frequency Mechanisms
Peripheral, SC, and supraspinal effects
Activates δ-opioid system**
Uses GABA
What does each feel like? (Sensory, Motor, Noxious
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)
Phase/pulse durations
Generally >150 µsec for all
Treatment duration and analgesia duration
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
Adaptation
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)
Interferential Current (IFC)
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”
Contraindications
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
Precautions
Sensory impairments
Chest wall
Active epiphysis
Cognitive/communication impairments
Regenerating nerves