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Electrotherapy is generally associated with
the word electricity. Electricity has been used for treating pain for
many years. Electrical stimulation directly blocks transmission of pain
signals along the nerves. Electrical stimulation has resulted in
promoting the release of endorphins which are natural painkillers
produced by the body.
There are several electrical stimulation devices available, each producing different
frequencies and effects. Some electrical modalities are:
1) Transcutaneous electrical nerve stimulation (TENS):
TENS unit can be used by patient at home for relieving pain on a long
term basis. It allows the user to adjust the intensity of the
stimulation, select high frequency stimulation or low frequency
stimulation. High frequency stimulation is called conventional which
is tolerable for hours but results in pain relief for shorter period
of time. Whereas, low frequency stimulation is called acupuncture-
like which is uncomfortable and tolerable for 20 to 30 minutes but
results in pain relief for longer period of time. TENS unit users can
also use electrode placements by placing the electrodes over the
painful area or over the nerve supplying the painful area or even on
the opposite side of the body.
2) Interferential current: Interferential current is mainly a form
of TENS. It modulates a high frequency carrier waveform with the same
signal as produced by a TENS unit. This high frequency waveform
penetrates the skin more deeply than a regular TENS unit, with less
user discomfort for a given level of stimulation. It is useful for
those patients who have not got relief from TENS unit. However,
interferential current devices are more expensive than the TENS
unit.
The positive pad behaves like ice which
causes reduced circulation to the area under the pad and reduces
swelling whereas negative pad behaves like heat causing increased
circulation and results in speedy healing.
3) Galvanic stimulation: Galvanic stimulation is beneficial for
acute injuries associated with major tissue trauma with bleeding or
swelling. Galvanic stimulators apply direct current whereas TENS unit
and interferential current devices apply alternating current. An
electric field is created over the treated area by direct current
which changes blood flow.
So, all these methods apply electrical stimulation to
nerves and muscles by adhesive pads placed on the skin. These devices
are powered by batteries but some also use adapter. These have very rare
side effects, mainly including allergic skin irritation under the
adhesive pads and transient pain from the electric charge. Electrical
stimulation should not be applied over malignancies or infected areas.
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