Transcutaneous Electrical Nerve Stimulation
The use of electrical impulses to relieve pain, also known as
transcutaneous electrical nerve stimulation (TENS), is a fairly recent development. The
idea, however, has been around for centuries. In ancient times, electrical eels were used
to treat pain. (Rosenberg 1) In the mid-1700’s, Dr. Ben Franklin wrote in personal
files his use of "electrical shocks" on his neighbor, with good results. (Kahn
1) In the late 1960’s, Wall and Melzack published the first article on TENS,
describing the "gate theory," the basic idea of TENS. (Kahn 130) This article
started a boom of many trials of TENS, testing how useful it is, and these trials were
written up in articles. By reviewing these articles, TENS should be proven useful and more
efficient than other pain relievers, such as drugs.
The best way to describe how TENS works is to describe the gate theory
mentioned above. According to the gate theory, pain is experienced by the body because it
travels along nerve fibers towards a part of the brain, the thalamus, or
"pain-center" of the brain, which tells the body to feel pain. The small c nerve
fibers that carry pain move relatively slow. There are quicker moving nerve fibers
available. These A fibers carry signals to the brain that reach before the c fibers.
Before, however, either signal reaches the brain, they must pass through T cells in the
spinal cord. If these T cells are considered as a gate through which the signals must
pass, an overload of the quicker moving A signals would block the slower moving pain
signal from reaching the brain. TENS sends electrical impulses along the A fibers, which
block the pain from reaching the brain. By using this method, pain can be mostly or
completely blocked from reaching the brain, and therefore not being felt by the patient.
(Kahn 129-130)
TENS is applied using a small machine, about the size of a Walkman,
which runs on batteries. Either two or four electrodes are connected to the machine, which
are then placed on the skin. Two electrodes are generally used, and the placement of the
electrodes tends to be at the place of pain and at a pressure point. This creates a
circuit, so the impulses are able to travel along the fibers. The TENS unit is then turned
on, but there are many settings at which it can be placed. Different settings include
wavelength frequency, intermittent (steady flow) or burst (short, sudden pulses of
electricity), and pulse width. The doctor usually predetermines these parameters. The TENS
unit is turned up until the patient can feel the electricity a little, and then it is
turned down a bit to a comfortable level. The TENS unit is very convenient, because after
one or two uses at the doctor’s office, it can be taken home and used when needed.
One of the most common uses of TENS is post-operative pain. This is any
pain following surgery, because pain often develops near the incision area after the
surgery. Many studies have been done comparing TENS against drugs, or normal physical
therapy in treating post-operative pain. One such study by Solomon, Viernstein, and Long
tested TENS against narcotic use in three different surgical procedures. About 200
patients were split into a control and experimental group. The amount of medication taken
over a 48-hour period after surgery was recorded. The results of the study showed that the
control took more medication over the 48 hour time period then the TENS group, therefore
showing that TENS was effective. (Solomon 144)
Another study, by Rosenberg, Curtis and Burke, also tested TENS against
medicine. This study did not have as large a sample size, with only twelve patients total,
split into two groups of six. After the surgery took place, the patients were provided
with whatever treatment they needed. The results showed that the control group used three
times the amount of medication than the TENS group. Nurses also noted an increase in
subjective respiratory functions, such as coughing, in the TENS group. Most of the TENS
group also said that they derived some pain relief from the treatment. This study also
showed that TENS was effective. (Rosenberg 130-131)
A third study, by Sodipo, Adedeji and Olumide, also tested TENS against
narcotics, and was similar to the previous study reported. This study had thirty patients,
split evenly into a control and TENS group. This study had much more drastic results,
showing that the control group used thirty times the amount of narcotics used by the TENS
group. Once again, nursing evaluations showed an increase in subjective respiratory
functions in the TENS group. Additionally, patients interviewed in the TENS group said the
TENS gave them adequate pain relief and preferred it to medication. (Sodipo 192)
A different study conducted by Ali, Yaffe and Serrette didn’t test
TENS against drugs, but tested the effects of TENS in different areas. They also split the
patients up differently, into three groups. One group of 15 patients received TENS,
another group of 15 patients had no TENS, and a third group of 10 received sham TENS. For
this third group, normal TENS procedure was carried out, but the batteries were reversed,
so the TENS unit didn’t conduct the electrical impulses. The results showed that TENS
was very effective in all categories. The vital capacity, which decreased greatly after
the surgery, was raised much higher in the TENS group than the other two groups. This
study agrees with the other studies, showing that TENS is effective in decreases
post-operative pain. (Ali 509-510)
Another study by Hargreaves and Lander tested the effectiveness of TENS
against no TENS while cleaning and packing an abdominal surgical wound. 75 test patients
were split into three even groups of TENS, no TENS, and sham TENS. The patients receiving
TENS reported a much lower level of pain after the dressing change than the patients
receiving no TENS or sham TENS. Drug administration was not considered a factor in this
study, and was looked at in the results. This study continues to show the same as other
studies, that TENS is effective in relieving pain after surgery. (Hargreaves 160-161)
There was one study found that did not agree with the other studies
found. This study, by McCallum, Glynn, Moore, Lammer and Phillips, tested TENS against
medicine need. Twenty patients were split into two groups of either TENS or sham TENS. The
efficacy of TENS was assessed by using a patient-controlled system (PRODAC) which
delivered morphine on demand for the patient. For the first 24 hours after surgery, this
system recorded the number of demands per patient, the total dosage of morphine, and the
plasma concentration of the morphine. No statistical difference was found between the two
groups in any of the categories measured by the PRODAC system. In addition to this, only
two patients out of twenty considered TENS worth continuing beyond the initial 24-hour
study period. Those two patients were in the TENS group, though. This is the only study
found dealing with the effectiveness of TENS with post-operative pain that did not confirm
the efficacy of TENS with post-operative pain. (McCallum 308-310)
As seen in the previous studies, TENS can be considered very useful in
relieving pain after surgery. Further, it is useful in many other situations besides
post-operative pain. It is commonly used during childbirth to prevent labor pains. It can
be used to help wounds heal faster. It can also join fractured bones that won’t
normally heal. There are other numerous uses of TENS, from back pain to multiple
sclerosis, but the most common uses are in rehab, either from surgery, broken bones,
accidents and sports injuries. Unfortunately, after the boom of studies done in the
1970’s and early 1980’s, not many studies have been conducted in recent years,
and the use of TENS seems to be on the decline.
There are many reasons to use TENS over drugs or other treatments,
besides the proof from other studies that shows TENS is more effective. One very
significant advantage TENS has over drugs is that it isn’t addictive. Some pain
relieving drugs, such as morphine, can be very addictive, which is not good for the
patient. TENS is not addictive, although the body can adapt to it. There are improved TENS
units that can avoid this, by a changing wavelength, and those equipped with a burst mode.
Another advantage TENS has is its lack of side effects. Some drugs may
cause side effects, or may cause harmful or fatal effects if mixed with another drug. TENS
prevents this problem, because the worst side effect is a little redness and itchiness
around the electrode placement area. This effect is minor compared to some effects caused
by drugs.
The TENS unit is also extremely convenient. It is small enough to fit
in a pocket, and can be used at home. It works on AA batteries, which are cheap and can be
bought at a supermarket. TENS can also be used during any activity, except for maybe a
bath, because electricity and water don’t mix.
A common misconception about TENS is that it kills pain. This is very
wrong, because it only blocks the pain. However, this leads to the best part about TENS.
It works when it is not on! After using TENS for about twenty minutes, the treatment will
last for a while afterwards. When a patient uses TENS for a few weeks, time between TENS
usage should increase considerably. After a while, TENS will be needed less, and the pain
will soon be unnoticeable. Eventually, TENS will no longer be needed and the patient will
be better.
Reflection on the essay
I chose this essay because I really liked
the way I wrote it, and I am also very interested in the topic. I was actually doing
this topic for an independant study class, but I was unable to design a good experiment,
and I had to drop the class. When I was given a chance to write a research paper on
any topic, this was my first choice. Due to the fact the I knew a lot about the
topic, and I had many good sources, the content in this essay is very good, which I think
is its strong point. I wanted the reader to get a good understanding of the topic
when I was writing this, so while the content is a little complicated, I made sure it was
understandable for someone unfamiliar with the topic.
This essay did not require much revision, although my thesis and
introduction were weak, so I had to improve those. The grammar in this essay is
almost perfect, which I was really satisfied with because my grammar is not always that
good. However, I was disappointed with my introduction and thesis, which were weak,
although I made them a little better with a few revisions.
When writing this essay, the most difficult part was combining all the
sources I had into this essay. I had a lot of sources, and I had to pick out a
select few that were good for this paper. I also had to decide how I was going to
organize the essay, so I just to decided to a paragraph or two on each study, which I
think worked well. Besides that, I also learned from this essay that the entire
process of writing cannot take place the night before the essay is due, especially a long
research paper.