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What is the Best
Parameters of Electroacupuncture (EA) Stimulation for the Treatment of Pain and Drug
Addiction
Han, Ji-Sheng
Neuroscience Research Institute, Beijing Medical
University Beijing, China
The ancient acupuncture technique of manual needling has largely
been modified by electrical stimulation administered via needles inserted into the tissue
(electroacupuncture, EA), or even via electrodes applied on the skin over the acupoints.
In this case, the parameters of the electrical stimulation become one of the most
important characters determining the effectiveness of the treatment. The electrical
parameters of EA consist at least of frequency and intensity. The intensity of electrical
stimulation can only be varied in a relatively narrow range, i.e., higher than the
excitation threshold and lower than the nociceptive level. Since we do not intend to
induce frank pain, the C fiber is not the target of EA stimulation. Therefore a pulse
width of less than 1 ms is preferable. T A13 fibers and part of the A f ibers are
identified by most researchers to be responsible for De-Chi (needle sensation). For this
reason, a pulse width of 0.3 to 0.6 ms is commonly used. Under this condition, a current
intensity of 2-10 mA is preferable for EA, and 8-15 mA for stamp-sized skin electrodes.
For normal subject or in acute pain patients, a higher intensity usually produces a
stronger analgesic effect. However, in chronic pain status, a moderate rather than strong
stimulation produces better analgesic effect.
Compared to the intensity, the frequency of stimulation seems to be
of wider variability and more importance. According to our study, the endogenous opioid
peptides (enkephalins, endorphins and dynorphins) in the CNS can be readily released by
peripheral stimulation of identified frequencies. Low frequency (i.e., 2 Hz) is apt to
accelerate the release of enkephalins and 13-endorphin in the brain, whereas the high
frequency stimulation 9100 Hz in human and rat, and 30 Hz in rabbit) are more effective in
accelerating the release of dynorphin in the spinal cord. Based on the results of a series
of careful study we have come to the conclusion that the best parameter for pain control
is a dense-and-disperse (DD) mode of stimulation where 2 Hz is alternating with 100 Hz,
each lasting for 3 seconds. Under this special parameter, all 3 kinds of opioid peptides
are released simultaneously, thus producing a synergistic analgesic effect. This has been
shown not only in rats but also in humans. A constant current output device entitled
Han’s Acupoint Nerve Stimulator (HANS) has been developed. While DD mode stimulation
produces best results in pain control and treatment of heroin addiction, patients with
muscle spasm caused by spinal injury were best treated with 100 Hz stimulation that
selectively releases dynorphin, resulting in a suppression of anterior horn neuron and
amelioration of muscle spasm. Supported by National Natural Science Foundation of China
and a grant from NIDA, USA.
Abstracts of ICMART '98
International Medical Acupuncture Congress |
