Hydas AD-2014 Instrucciones Servicio página 18

Introduction
Theory of therapy
Transcutaneous electrical nerve stimulation (TENS) is a non-invasive tech-
nique in which a low-voltage electrical current is delivered through wires
from a small power unit to electrodes located on the skin. Electrodes are
temporarily attached with paste in various patterns, depending on the spe-
cifi c condition and treatment goals. TENS is often used to treat pain, as an
alternative or addition to pain medications. Therapy sessions may last from
minutes to hours. The use of electrical stimulus for pain relief was popula-
rized in the 19th century and became widespread in the 1960s and 1970s
using battery power.
Transcutaneous electrical nerve stimulation (TENS) was fi rst introduced into
current clinical practice following Melzack and Wall's gate control theory of
pain in 1965. Davis (1993) and Lewith (1984) explain the gate control theo-
ry of pain as follows. An area of the dorsal horn of the spinal cord, known as
the substantia gelatinosa, acts as a gate to nociceptive impulses. It receives
myelinated nerve fi bres , the largest being A fi bres, and small non-myelina-
ted nerve fi bres (C fi bres). If pain impulses pass along fi ne myelinated fi bres
and C fi bres rather than along A fi bres, the gate is opened, and the patient
perceives pain. If A fi bre transmission of impulses is greater, the gate may
be closed.
There is also evidence that the TENS machine enhances the production of
the body's own natural pain killing substances: endorphins and encephalins.
Human body produces endorphins and encephalins, which are opiate-like
substances to counter the pain. Low frequency stimulation causes the re-
lease of the endorphins and encephalins.
Why consider digital pain relief?
Pain is a warning signal -we need these signals to tell us that something
may be wrong with our body. Without it, we may do not know that part
of our body might be damaged, thereby damaging them further. However,
once we have identifi ed damage, pain serves little purpose. In the case of
chronic, regular pain it can signifi cantly interfere with daily activities and
the quality of life.
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