16 NEUROPROBE
®
500 PRO USER MANUAL
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TREATMENT GUIDELINES
Introduction to Medium Frequency Currents
Medium frequency (MF) currents may be described as electrical currents applied to the body for therapeutic
purposes, which fall in the range of 1000 to 10,000 cycles per second (Hz). This is in contrast to low frequency
currents (0.1 to 1000 Hz) such as LVPC and HVPC, and high frequency currents (1 million Hz and beyond), which
include ultrasound, shortwave and microwave diathermy. Medium frequency currents are very advantageous for
clinical use due to their ease of skin penetration at lower intensities.
Normal human skin reacts differently to different frequencies of current. Specifically, there is an inverse relationship
between the frequency of the applied current and the skin’s resistance to it. Medium frequency alternating currents
in the range of 1000 or 5000 Hz provide markedly lower resistance to penetration than low frequency electrical
stimulation commonly used in TENS, LVPC, and HVPC stimulation. Medium frequency currents can be used in
Bipolar or in Quadripolar Interferential mode for patient treatment.
With medium frequency currents, the energy of each individual pulse is low, providing for stimulation of only one
or two neurons. Since the pulses are coming in very rapid succession, stimulation of surrounding neurons occurs
prior to completion of the previous neurons’ refractory period. This allows for asynchronous activation of individual
sensory neurons, mimicking the natural physiologic process of the intact nervous system. This is not the case with
low frequency stimulators (0.1 to 1000 Hz), which are capable of only stimulus synchronous neural activation.
Medium frequency currents provide rapid analgesic effects. This occurs due to rapid depolarization of non-
myelinated pain-transmitting fibers, which block pain transmission, further contributing to high muscle contraction
capabilities. Additionally, medium frequency currents have been shown to alter the vascular dynamics affecting
local and possibly systemic blood flow to the muscle(s) being stimulated. The unique characteristics of medium
frequency currents (higher percent duty cycle, higher average current intensity, and wider pulse widths) can
significantly increase blood flow by altering the metabolic activity of muscles.
PLOT OF IMPEDANCE AS A FUNCTION OF FREQUENCY USING EPIDUCTIVE SYSTEMS
