TENS; BOOK CLINICAL ELECTROTHERAPY NELSON.pdf

Tens practical aspect

1. LL CHAPTER 7 0

Transcutaneous Electrical
Nerve Stimulation

Jennifer Klein and David Pariser

K. M. C. LIBRARY

Management of acute and chronic

Pan presents ph hp wth one of thee
sos challenging lil problems Pans ea eo ih on of
de vid vary odias seen nea ents ar den
smn (TENS) as ben und tb se car ae til nee
Sater, we dicts te neun era od pl I
nent etre, and lal spre
TENS ino ttl novel npn tin modo. vous go ack othe
seat Greek and Roman os The st rca cl ree
‘shen Senos ars sed te cia fa cn ea LD,
The Latin origin of the word “torpedo” is noteworthy because it refers tothe
hdd fect ated by Ching e
Inthe lite a tu; he za eng lt nergy De rey
re ere
bret lan es nthe developmen ES he ner Le
Leyden jar in 1745, Galvan experiments wih direct current onthe nervons seen
and Faraday' discovery of alternating current in the 1830s:' Unlortamatel widest à
Se bass e gull tied ri, aan (DD bi
‘ead (and often imprudent use. Pscudomedical personnel toate ac ni
BS wa one a ey Cog, slat Cog AO A of
co sloped by Melzack aud Wall. Th
11, a cnt Famevok as devel Mack nd Wa iy ps
Whale ee meen’ chen pd a ae ee
‘tera neon toca docu pl Th

Ps "le in prompting research into the el eltivenes of

mbing

played an impor
* Shealy eme
applied the gate theory by implanting electrodes into the dorsal colanın of the

2. 210 “cuca come

sion! He attempted to

latively erude TENS-like de

prove effective; secondarily,
he abil

cord, applying electrical current to prevent pain tra
screen potential candidates for this proce

vice, Asa sereening method, the TENSA
this erude, transeutaneonsly delivered s
induce varying degrees of pain relief! These secondary findings prompted an in
estion into the application of transcutancons

Surgent interest e t the development of modern, soph

ti

ion was discovered to hav

PAIN

TENS is presently being used to treat a wide variety of medical, orthopedic, and
surgical conditions. Considering the somewhat stubborn nature of pain, TENS has met
with favorable success. Documented successful results of up to 60 and 70 percent reli
in patient populations have been reported.‘ Other authors believe that the maximal
benefits range from 15 to 50 percent.»

Pain is the symptom that we dre attempting to modify with TENS; because of the
complex and variable nature of pan, iti important fr the clinician utilizing TENS to
be familiar with various aspeets of pain. One way of categorizing pain is as ether acute
or chronic.

Acute pain is caused by

an, and it serves the
des Me pas
research has been conducted on experimentally induced acute pain; however, scientific
measurement is difficult because of the subjective and individualized nature of pain and
ARR Bale, ln gence. Duane, cue ps à Bo stay Qu
chronic pain, is usually self-limiting, and is more easly treatable than chronic pain
Chronic pain does not tend to have a biologie function and often imposes desata
Comtat socia, and EEE Akte. The under hrs aero.
ISDE mesita ohren pn isnot welbanderstood, thus cool eve
ment. Drug dependence (or addiction) and personality changes can further complicate
successful treatment in the chronic-pain patient. Treatment of pain, especially of chro
ic pain, constitutes a serious clinical and societal problem. Estimate
annually on pain reduction reflect the magnitude of this proble:

Physical therapists play a major role in the evaluation and treatment of painful
dle. ds phyla Merit oes llo Ise en Gis segs sd 8
pain control clinics, exposure to chronic-pain patic creased. Loeser notes that
no drug, surgical procedure, or psychologie treatment can claim a 25.percent efficacy in
au lei pain late ocu ee pateo nr
spond to TENS, a major contabuton ohh alth and wellbeing of such patients wil
ak

or tissue-damaging sit

Pain Transmission
In order to begin to treat pain effectively, it is important to understand some ofthe basic
neurophysiologie mechanisms of pain. One question, for example, is how pain is per-
ceived by the nervous system. Although this section is not intended to be a complete

3. I TRASCUTAMOUS HITA nu Sharon 211

siew ofthe peripheral and «

Fe receptors and pathy
pe transmitted

Yoxious stimu to the

{rs Although these en

there has been some debate

rl ners
Shake RS systems, we hope to review the peripheral
‘hcl the eh seman a ale E heen
ders the akin
ous recep

aa an a e
Be a ar si ler
gain stimulas—is transmitted via the

In the peripheral nerve

ve ening,
re Structurally, these undifferentiated
inal, they are specific terms of the
dc he free nerve receptors,
ere plays the Adela fibers and the €
re ch hepa
A-delta fibers. The © fiers, whi
iting cary the burning, aching type of pa.

je the (larger) A-delta and (smaller) C fibers are randomly
sean Just before the peripheral more eater the tied ocd ee pa
mo lateral division, and the A-delta fiber into anne dt, af br bo
mot, The medial division enters the spinal cord, immediately forming a large bundle of
fibers in the medial dorsal horn. The smaller fibers enter laterally. into the tract of
Lisauer. The smaller fibers travel in this tract for several spinal segments bef
entering the dorsal horn of the spinal cord

The ext structure and neural circuitry of he afferent fbers in the dorsal horn
have been examined, but there is still debate and incomplete underst;
the true path.® Both the A-delta and C fibers are known to make excitatory synapses on
the substantia gelatinosa neurons inte dorsal rey area ofthe spinal cord In addition
{lon sinapses are made by the Adela fibers onthe nucleus propios and by the
Ciberson the marginal cells, in the spina cord, The substantia gelatinosa neurone hove
ken implicated in making inhibitory synapses on the marginal cells. Repetitive sinne

ation of the substantia gelatinosa by the large fibers may result in inhibition of the
marginal cells, thereby modulating the threshold of pain.»

Bishop states that the spinal cor isan integrative center for sensory processes, not
insta relay station. She goes on t tate: "The vst majority of onguingdotel yoo pe
“str out without ever reaching consciousness."

The spinothalamic tracts convey nociceptive impulsos to the brain. Most
‘earns project tothe contralateral hemisphere sde and respond to
and to noxious or tactile stimuli. The spinoth
‘ont nd tal (edn pt acs Te wont
‘nie tract projects to the posterior thalamic nucle and s associated with spate ned
temporal discrimination of pain and touch. The paleovision projects medial tn the

poral diseriminat L aspects of pain. As the spinothalamic
tet © spinal cord, collerals ae sent out to the reticular formation.

song the main reticular for EN
¡resto and he mesnep een em Te rele Reto 5
Walamic relay nuclei, and the cortex to which they project ately connected

nse pressure:
ie tracts consist of the lateral (neo.

cious pain awa

4. -

212 ca cmo mer

Figure 10-1 Schemati repre.
le. From Chusid : Corel: ee eee

tive Neuroanatomy and Func- Besen)

that it makes litle sense to sort out the relative sensory functions of cach.12 A schematic
representation is shown in Figure 10-1,

‘There does not appear to be a clear separation of areas receiving noxious and
nonnoxious input in the thalamus, just as the separation of neurons is not clear in the
dorsal horn." The neospinothalamic tract is thought to ascend to the ventral post-
erolateral nucleus (VPL) ofthe thalamus, while the paleospinothalamic tract is thought
to project to the intralaminar nuclei of the thalamus. The thalamic cells project to the
somatosensory cortex ofthe postcentral gyrus. The exact role played by the cortex in the
transmission of pain is uncertain at this time.™

ts

‘THEORETICAL BASIS

A solid understanding of contemporary pain theories and research is very helpful to the
eficacious application of TENS. Although the precise mechanism by whicl
on the nervous system to induce pain relief is not completely understood, the
several possible explanations of the induced analgesic effet
‘The specificity theory indicates that stimulation of a specific peripheral nerve
receptor produces the sensation known as pain. The nociceptive input is thought to be
ted by the A-delta and € fibers in the periphery, through the spinal cord (by the
and then to the ventrolateral portion of the thalamus
Supporters of the specificity theory believe that the neural tissues responsible for
transmitting pain have unique anatomie and physiologie properties that make them
suitable forthe task of pain reception, However, serious laws have been shown to exist
in the specificity theory. For example, i the above:
transmission lines for pain, it follows that disrupt
Melzack and Wall found that pain was still pres
lateral spinothalamic tract.

tioned pathways were the sole
them would obliterate the pain.
{allowing surgical lesions of the

5. FO, ANCIANOS LCA NERVE SIIMULATON 213

ther major pate

since, OD tension theory E ld te pater theory, developed by
eee he teller theory agente that ts bay tine CAD ae
depre bythe ar ne rat nonspe

Peralta be lala Te and hat the perception of pan

ays nth ulation. The pattern theory also implies
en a relatively slow-conducting system and is synaptically
AA fiber. The u theory has been criticized for
ion specialized receptor unite tt hase a

il to acconnt for the differences
d thresholds to different stimulus intensities
bby Melzack and Wall was the major impetus
ion. They proposed the existence of a gating,
alter ascending transmissions of nociceptive
‚path mechanisn by shih the gate influences alfeventteanssson e aed on
the quantity-of input between A-delta and © fibers to the dorsal hora ofthe spinal cord.

is shown in Figure 10
nosa consists ofa group of cells located in he dorsal horn of the
spinal cord, ‘The A-delta and € fibers project to, and synapse on, both the substantia
gelatinosa and the first central transmission (D) cells in the dorsal horn, It was thought
that the Teells, when sufficiently stimulated, activated an action system tha is respons
{We for response and perception, The T cell are, in turn, excited by the A-delta and C
fiers. Melzack and Wall Felt that the substantia gelatinosa modulated the transmission
from peripheral (A-delta and €) Rbers to central (1) cells by presynaptically inhibiting
the fibers from stimulating the T cells. The gate is “closed” by high levels oF activity in
the A-delta fibers. Using the negative feedback system, the A-del

in sesponse ranges, adapt es, 4
The development of the gate theors

hehind renewed interest in neural sti

mechanisan at the spinal level that could

fibers exert pre-

ws zp

cremate diagram of he te contol theory of pin mechanisms: L,
Gizure 10-2. Scherer Sethe small-diameter fibers. The fibers project to the
nos (SC) and rs central transmision D cel. The inhibitory effect
sabi noria y ee oa
See cl Ss. Te ee cnt a epee y
Beers oy eatin eer system 0 he central control mechanisms; these mecha-
tuning rom the ga control system, The cel projecto the entry
piss, in turn, prole, Excitation; =, inhibition (see text. (From Melzack Pa
lam: A ne theory. Scene 150:971, 1965.)

6. a

214 cunteataurcrronaearr

synaptic inhibition on the cells va Facilitation of the sustantia
ed” with high levels of activity from the C fibers, preventin
“T-cells. This results

wt result isthe per
sof pain res aspects of

the substantia
oll excitat
ception of pa

either spatial or temporal summation. 1

While the gate theory has opened n

the theory have heen questioned. In 1978, Wa although there is no longer

any doubt that a gate control exists, its functional role chanism remain

© open to speculation and experiment. He ako fecs thatthe role ofthe substantia gel
osa in any function is still unknown,

Much of current pain research deals with enkephalin and endorphin release. Both
enkephalins and beta endorphins are endogenous neurotransmitters that have been
found in the brain, These neurotransmitters have morphine-like properties and have
been reported to produce analgesia in both animals and humans. Enkephalins produce
analgesia, when released from their neuron terminals, by combining with stereospecific
‘opiate receptors to depress the reception ability of the receptors."® The majority of
‘opiate receptors are located inthe spinal cord and in the frst three laminae ofthe spinal
cord.!? Enkephalins have a 2-min halflife and quickly lose their analgesic effect once
stimulation stops.

Beta endorphins are located in the pituitary gland. They appear to be more potent
than the enkephalin. Part of the beta endorphin molecule consists of ACTH, which is
known to be released in response to stess and multiple trauma, The 4-hr halflife of
beta endorphins translates into longer pain relief after stimulation." Release_of beta
‘endorphin can be increased by low high-intensity peripheral nerve
Stimulation 2° ail

Gmulation of the C fibers is known as hyperstimulation analgesia: this
I endorphin release, subsequently activating descending control on the
dorsal horn of the spinal cord,

Descending control of pain is thought to act by the following paradigm: The brain
stem contains areas that may exert an inhibitory influence on the dorsal horn of the
spinal cord, thereby inhibiting the ascending system. These areas are located in the
periaqueductal gray matter and raphe nucleus of the brain stem. Descending inhibition
has been found to be a more effective analgesic than has ascending inhibition >

experiments with the drug naloxone (a morphine antagonist) have supported th
‘endorphin theory, In these studies, endorphin release was stimulated by low.frequen-
ey, high-intensity TENS, After injection of naloxone, the analgesie effect of the en
dorphins ceased, and pain returned, suggesting that the analgesia resulting from release:
‘of endorphins might be mediated in a fashion similar to that of morphine.2

Substance P is a neurotransmitter necessary for the transmission of pain. En-
kephalins and beta endorphins have been shown to block substance P, thereby pre
synaptically inhibiting afferent nociceptive transmission,

Serotonin is a neurotransmitter that has been found to be important in many
behavioral stätes.22 I m c-in-nociception, because decreased

7. 215

EQUIPMENT SELECTION
implest form, may be d hand-held battery-operated,
cleetrieal pulse crieal st sously through elec:
‘wires. Optimally, the un is worn by the patient,
jeté mobility. The energy source fs supplied by either a rechargeable ora
disposable battery. Battery life is dependent on the patients operating schedule, the

storage period.
timulators are shown in Figure 10-3, Presently, most units have
le that have two output channels, which allows for at least four
| Such a design affords the practitioner flexibility with regard to.

and t
reral types of st
two operating chann
electrode attache
letrode placement
Both the quantity and qu
Pulse rate, pulse width,
rates or pulse w

ity of stimulation are determined by three parameters:
ensity (amplitude). Some units have preset pulse
js always an adjustable setting, controlled
Riya Se pall strates the relationship of these
Pe ene on train of pulses. There is considerable variety in the elect
danetenstie specifications of various units Howson evaluated

found the follo

8. 216 cc coma

M
Frequency Hz) 90-160
Pulse Width (ms) 75-350
Intensity (mA) 30-120

should be listed by the o
ications shold be
linie may be made with the use of an aseillascape and a LAR resister, Although this
calibration is valuable for establishing the wave form characteristics delivered through a
sistive load, it should be recognized that the skin is a complex resistive load,
has ls: modifs the TENS wave fo ists by
aches, and affects, the subeut
mon types of wave fo
ar pul

pacity to subst
the electric potential
The to most co

its are the

recta and easy

have been made regarding the “optimal san

ay be litle difference among wave
‚beutancoms tssies

that provides the greate

€ form to use clinic
wn types once they have passed through

dig is preferable for most clinical situations, For example, a dus
that allows adjustinent of all rameters is prefe
fe NS unit is a display of actual current, pulse width, and frequency

ters, The display feat

allows t

clinician the ability both to record effective
xs and to document them while doing research. Having several
¡types of TENS units available will allow for optimal patient trials, For ex

patients will respond to one TENS unit but not to another u

with the many different types of TENS units available
from a large and varied assort
fully evaluated, because diferent patients and different di
diferent types of electro
“The most popular type of electrode is the carbonized silicone variety. It requi
conductive gel to decrease impedance between the electrode=skin interface and has an
adhesive patch for skin Patron. Its advantages include beingslurable, reusable, and less
costs than other types of electrodes, but i has the disadvantage of increasing the
incidence of in Trtation secondary tothe conductive gel or adhesive used, Occasion-

Pare mien

Figure 10-4, Pulse charac- L

teristics (parameters) ee

9. 1 SCAN

Figure 10-5. Electrode types.

ally, electrode paste will dry out under the electrode, increasing Fesistance and decreas-
ing the electrical flow. Some patients using TENS far longer periods of time find the use
sfeleetrode gel and patches bothersome, especial en pain stem from a dificult-to-
reach area, such as the lower back and cervical regions

api terative choice i the Karaya electrodo. The Karaya electrode has flexible
conductive sheets made of a hydrophilic polysaccharide that becomes selfadh

when moistened This electrode type may be used far several days and has become
active alterstive to standard electrodes: Al
pensive than are carbonized silicone electrodes, the homogeneous current
the surface ofthe Karaya electrode reduces the possibility of the development of "hot
spots.” On carbonized silicone electrodes, hot spots may occur ssa result of electrodes
drying Sut and producing uneven patches of skin resistance. 2”

A variety of other disposabl electrodes is available, all of wh
of being pregelled Several examples are show

several itera

Ivantage
in Figure 10-:

mple, a lage-surface-area electrode for postopera-
as opposed to a smallsurfice-aren electrode for acu

puneture-point stimulation.
2. Patient preference; for example, cost, ease of application

3. Patients skin type: for example, the patients
material

lity to reuse,
ity to adhesive-patch

Numerous electrodes are available for postoperative use. These electrodes are sterile,

are selfadhesive, and have conductive paste. Some desirable characteristics in postop-

2. Total surface area is conductive, adhesive, and sterile,

2. Easily conforms to body contours.

10. 218 coca comer

3. Durable, in th
Salay postope
4. Easy application and removal

the conductivity and adhesion last forthe d
tive perio.

clectrodes are cas aligned with coved incisions because they

Aa or cam be notched, Others can be eat o ita sal incon. The us of small

cleciedes over aıpumetnre points ls eon recommended fora variety of operativa

rennen. Have en the quality ofthe trade andthe type of surgical procedure
taken

EVALUATION

As with any form of physic
treatment with TENS is
patient eli
what under

therapy, a thorough patient evalu

al presentation, its critical thatthe practition inderstanding of
nt pathology is producing the subjective complaint. This will provide a
Logic basis on whieh o proceed with the TENS evaluation. In addition, the evaluation
will preve apis from inadvertently focusing on only one aspect of the patients
total probl Sis but one of many treatment approaches that physical therapy has

| to offer, and referrals lor a “TENS evaluation” only should be discouraged.
| ‘The evaluation should begin with «thorough history. When evaluating a patient
with chronic pain, certain arcas need to be aldressed
1. Previous and present pain medications
| 2. Treatments—physical therapy, chemotherapy, xr
| 3. Employment status and activity level
4. Methods of qualifying and quantifying pain. For example, a numeral rating scale

vr pain-deseription word list may be used to he
condition. In addition, repeated quant
the patients longitudinal response to

ily the patients pain
ve measures may help to documer
ENS treatments,

lowing the history and background, the evaluation should proceed
culoskeletal and neurologie exams may be perfo

Gait evaluation may also need to be perfora
objective findings are assessed,

usual, Muse
«las appropriate for that patient
Al. At this po

dan appropriate treatin

tthe subjective and
regime is planned
IETENS is to he incorporated into the treatment program, the physical therapist
nay wish to evaluate the patient in terms of specific electrode pl
tion parameters

nents and tin

CTRODE PLACEMENT

Once the patient has be ine to use TENS
overall physic in TENS application is the place
ment of the electrodes. Choosing successful stimulation sites appears to be a combina:

py treatment plan, the

11. TO TRNOSCUTANLOOS ECE NIV STIMULATON 219

son of art and Science. Diligence in ab
heving good results with TENS. 4
Fear idea of the anatomie and
feat the choice of electrode placer
‘The most common approach used to locate sites is to place
When an electrode is placed over the painfl area, pain relief may be due (at last in
par) o stimulation of an underlying dermatome, trigger-ör acupuncture point.
Denwatomal placement is another method af choice. Usually, the dermatome

verlies the corresponding myotome or sclerotome, as shown in Figure 10-6. Fre
quently, deeper forms of pain may he treated using a selerotome distribution, However,
ions ofthese deeper myotomes or slerotomes difer kom the subeutaneous
dematomes, which overlic the deeper structure (for example, the L2-3 den
er the L5-51 myotome in the region of the buttock)"
Mannheimer suggests three ways in which a dermatomal techni
lined: (1) placement within the involved dermato:
thedermatome (for example, trigger, motor, or

ining these locales is probably a Key actor in
basic understanding o neuroanatomy, along with
tnorphometicstrctures producing the pain, will

Hein

atome lies

je may be uti
(8) placement on a specific site in

ture point); and (9) placement
ar dermatome (for example, the

ca both anterior and posterior aspects of «parte
úrico region). 22

Using the acupuncture, trigger, or motor points is advocated by some clink
Sans 3231 Melzack and coworkers reported a 7I-percent correlation between acu-
puneture and trigger points. ® À 50-percent correlation has lv
Aapuncture points and superficial areas o peripheral nerves.
ain relief was achieved when a varity of patents used aeupuneture and trigger points
With brief, intense TENS.*? Acupuncture points may be located by electronic probes,
because these points are more conductive than the surrounding tissue, The low re

n documented between
Greater than 50 percent

K. M. C. LIBRARY

Figure 10-6. Segmental inner
vation of right upper extremity,
anterior view. (Reproduced
with permission, from tnman,
and Saunders: Referred pain
from skeletal structures.) Nery
Ment Dis 99:660, 1944.)

12. sistance of the acupuncture point corresponds to the areas of vasodilation or active
pseudomotor glands. 97
Another site to stimulate for pain relief peripheral nerves, Electrical stitution
is effective in eases of pexipheral-nerve injury and peripheral neuropathy. 9" Picaza
and cossorkers document 50- to 100-percent rei of pain with peripheral-nerve stn
jents with various sources of pain. They found that pain suppression
05280 tests hy stimulation of peripheral nerves that were not directly
Ih the resultant à ly less.

ulation in
resulted in 120
involved, altho

A technique used to locate the most superiial aspects of peripheral n
been described. *! Using one channel of a TENS unit the elinician holds one electrode
while the patient holds the other. The clinicians index finger probes over the most

superficial point of the desired peripheral nerve, increasing the amplitude of the:

‘output until the patient perceives a numbing feeling alomc the course of the nerve.
ne advantages, ofthis technique are a follows,

Tiypassed. Fist, the entancous peripher
second, selective blocking of

1. Peripheral receptors
have been shown to adapt rapidly to
superficial receptors has been shown to be inefeetive in completely blocking
the effects of TENS transmitted to the nerves 2

2, Remote stimulation of deeper nerves is possible before the nerve branches to
innervate deeper Fields

3. It may be used in sensitive derm mditions

4 ies less amplitude of output to stimulate directly over a nerve trunk,

5. It may be an effective means of ocalizns aempuncture points,

Another area of electrodo placement location is paravertebral. Rel

specific spinal-cord segment and nerve root may bea effective TENS technique
control radicular pain, Mannheimer suggest that one electrode be placed paraspinally,
while the second is placed on the corresponding dermatome or on the superficial

peripheral nerve. Regarding paravertebral électrode placement,
actual neural-tssue Stimulation. For example, is the deep st

structure being stimulated? Berlandt indicates 0

stimulation do not report paresthesia along the nerve; there

fore, effective stimulation of the peripheral nerve root at the paravertebral region E
spparently not accomplished.

An alternative approach is contralateral electrode placement, which may be used in
cases where the painful area or the desired ipsilateral stimulation points are hyper.
esthetic or irritable. Some examples are postherpetie neuralgia, causalgia, and reflex
sympathetic dystrophy

Variations that the clinician may explore are numerous. For example, the arca of
pain may be surrounded by a bracket (or criss-cross) method (Fig. 10-7) Stimulation
‘of a remote or unrelated area may produce pain relief. Transcranial placement is effec
tive for a variety of syndromes, including migraine headaches 0

Before th julus parameters is discussed, two additional points need
tobe covered. First, the necessity of perceptible paresthesia for pain relief is currently
‘under debate. Some studies support the importance of eliciting perceptible paresthesia

13. Esos! re

and ineffective. The exception o
gunetunhhe TENS (discussed in
re TENS stimulation is

at factors pde:

istics are modified as curres
wow electmanalgesta is obtained,
to make decisions regarding 1

ment concept
y basis on hi

J consensus on optimal paran
Jy. this area has not been wellsstudied,

Eh (20 to 60 ts'—mode. The intensity is
rons passsthesadlibe sensation. withon

€ theory. in
ipa and beta aferents th
pathway: The conventional
peas to have a shorter lent

stimulus. compared to other
with this method is variable. Treatment
© daily by the patient at home, or three

sed continuously as is the ease with postapera-
1 schedule is better than a discretionary
nal mode and of other modes is

14. ee

222 cuca acom

| DOMO Anna nn

mes

Li MM

Acupuneture-like, or low-frequeney, TENS is another com
low-frequency (1 to 4 Hz) and a wide pulse width (150 to 250 ps) are used in the
acupuncture-like techniques. The intensity is gradually increased to the patients tole
lance in order to produce a strong muscle contraction in the segmentally related myo-
ture form of ES activates the smaller A-delta and C fibers and the
ind beta bers. Analgesia may be induced by stimulating release of endogenous
opiates—increased levels of endorphins are found in CSF following acupuncture-like
TENS. Relief of pain has been shown to he reversible with naloxone.33 Compared
to other stimulation modes, the acupuncture form of TENS takes longer to produce pain
‘once induced, however, the relief is longer-lasting. Treatment time is usually 20
to 30 min once a day

Alpin

S controls are s
er limits. For example, the frequency is greater than 100 Hz, the pulse width
is 150 to 250 js, and the intensity is increased to the highest level tolerable by the
patient. Melzack proposes that the brief, intense TENS technique either may disrupt
the memory-like process for pain orn al biasing mechanism.& Other
studies have demonstrated a deer ; resulting in
slowing of conduction velocity; this suggests that a conduction block may be an impor-
tant physiologie result of brief, intense TENS, 1.20
Burst, or pulse-train, TENS combines the h
high inte

15. 10. TRANSCUTAMEOUS ELECTRICAL NIRVESTINUIATON 229

Deca allows simulation of pa
tnelycomforable sensation pcs

ring bes wie the patient perceive y rele
rely comfort St Tc Heh Tema requnes) When med Ike
ow-freq TENS with a wide pulse width, the burst technique has been shown to
produce pain relief that is partially reversible by naloxone.
¡Modolated TENS provides a bin van a pl ih,
sity, which will automatically vary the nerve silos. The variation 6 believe o

ve rate, or inten

prevent normal adaptation of nerve fibers to a constant current

One of the continuing ande r involves which
stimulation parameters are most effective. Results supporting € ein
variety ofelinieal syndromes m want literature. At this time, ¡appears
that indivicwalizing both e ters ás probably a
critical factor in

faversies surrounding the use of T

be found in re

ds and stimulation pu

Ävieving success with TENS,

CLINICAL INDIC

JON:

o effectively treated by conventional (high
Ss effective in tr il

to

hampered by pai "
at of various 1

has been effectivel
ip pointers, and mild a

been studie

ts have been documented i
sprains and strains."
1 acute skeletal pain. In
90 and 100 percent
impot metive therapy for emergency departments,
Del TENS has been found to be effective include rib
¡volar joint-myafascial pain dysfunction, acute tend

femoral pain.

an emergeney depa
percent of the

recommend T
Other acute-pain conditions fo

Chronic Pain
Acute pain may serve a useful

injury by

symptom—to prever
‘serves no apparent purpose

purpose as
however

jon. Chronic P

limitina fi
a disease proc

Chronic-pain patient
treatment outcomes. The clin

present certain problems that may or may not affect
"an should be aware of the potential for drus depen
Uisturbances; and disturbances of sleep, appetite, and
ie patients demonstrate a deerease in pain tolerance

y of endorphins. TENS is a very attractive
because of its nonaddietive and noninvasive

dence: psychologic or beh

ponubly secondary to ©
of these pat

native fo

Arequeney) TENS.

16. WA EE

228 cuve cromo

Numerous conditions that produce chronic pain have been successfully treated
with TENS. Some of the more frequently treated syndromes include low back
pain 329333 rheumatoid artis," degenerative joint disease 2202.52 cansolgia,. 5
peripheral neuropatl mb pain SH ane
Ger migra pts to correlate sp
ciñe sin relief have been mar-
ginally nent, however, that persistence in trying various
parameters and placements improves the chance ofa successful outcome. 24"
Some interesting points regarding treatment of chronie pain with TENS have been
discussed in the literature, Long found that patients with psychogenie pain are rarely
oftheir symptoms with TENS and often report intensified pain. He also noted
4 poor response in pain of central nervous system origin and in neuropathic types of
Peripheral nervous system pain (for example, diabetic and alcoholic neuropathies)
Good results were accomplished in cases of peripheral nerve injuries, phantom limb
pain, and postherpetie ncuralgia.% Other researchers suggest that clinical results are
not based on the type of disease but, rather, on the presence of trigger points and
denervation. The best results occurred in patients with trigger points and without
signs of denervation. Findings from a study by Wolf and coworkers on chronie-pain
Patients suggest that TENS is more effective when no previous medical or surgical
treatments for pain have been performed.
As a group, chronic-pain patients can be a dificult population to treat: howes
recognition of this as a multifaceted problem, and a creative approach, can produce
gratying results. Techniques such as having the patient keep a pain diary can be
beneficial in determining pain pattems and treatment schedules. Certainly. a study
documenting results of 982 pain patients, 35 percent of whom achieved adequate thera.
py with TENS, demonstrates the potential for this innocuous form of treatment in
chroniepain therapy.

peripheral nerve injury.2®% phanton
e headaches,S and postherpetie n Atos

al
ters and electrode placements with y
‘There is agro

Postoperative Pain
Another common clinical use of TENS is in the manager

t of postoperative pai

There are numerous types of surgeries for which TENS can be utilized, i |
abdominal, thoracie, and orthopedic procedures.

A key to a successful postoperative TENS program is adequate preoperative patient
education. We have found that this facilitates postoperative patient involvement. The
preoperative visit should include:

1. A basic explanation of how TENS works. For example, a statement such as

“TENS works by serambling or blocking the pain messages carried by the pain |

nerves” is often an effective way to introduce the philosophy of TENS to the
patient

2. Application of th
stin

electrodes) to the patients skin. Prefera
hs is applied first to a neutral site (for example, the arm) so that the
patient may experience the sensation. Then, the stimulus is applied near the
‘operative site. This allows determination of a comfortable intensity setting so
hat the unit may be turned on postoperatively while th
recovery room.

ly, the

patient is in the

17. TO TRANSCUTANCOUS HECIRICAL NERVE SMUIATON 225

3 Al dang which the patent operates the TENS unit Thilo the patient
Mom comirtabe with the ni many pins ml be rfl ol just
the stimulus unless given the chance to do so remporte.

4 Am ciation tht pin medication wil he ruhe postoperatively but that

the TENS u À decrease the neo es he Le
beneficial the need for medication, and why 1

Postoperatively, the steile TENS electrodes ae placed parallel to, or surrounding, the
incision before the surgical dressing is applied in the operating room. The units usually
atached to the lead wires in the recovery room, and intensity is increased to the
predetermined level. The conventional mode is most frequently used; however, some
patients have a better response if he pulse width is also increased. The unit is usually
kept on continuously for the first 24 to 48 hours postoperatively. Batteries must be

uged frequently in order to maintain an adequate level of simulation. Again, the
patent should be encouraged to control the TENS intensity output, For example, some
patients are able to cough more efectively by turning the intensity up prior to each
coughing attempt.

‘Smooth postoperative ince by other members of the health-care
team can be facilitated by adequate inservice training and by written communication
among the sta. lude a chart above the patients bed that lists wearing
time, machine settings, electrode placement, battery usage, and any special precau
tins

TENS has several advantages over traditional postoperative pain analgesic, in
ing decreased risk of addiction and physiologie depression, as well as increased patient
participation, Numerous studies have been published on postoperative TENS, docu.
menting decreased narcotic usage,®*~"! increased ability to cough and breathe deep-
191 decreased incidence fatelectasis 72% pneumonia, and ileus: and decreased
hospital stay.7!-73 Problems associated with postoperative TENS can include patient
relucance in accepting this type of pain management; poor health-care personnel and
patient compliance, poor understanding of the units operation, and possible skin
intation

Other eee ea
The effectiveness of TENS for a variety of other conditions has also been researched,
And appears to have potential applications in numerous other (painful and nonpainfl)
conditions: Kaada has demonstrated peripheral vasoditon and increased atte tom,
erature of 7 to 10°C in patients with Raynaud's disease and diabetic polyneuropathy
Using low-frequency TENS.” The associated ischemie pain was also relieved. He pro.
Poses a mechanism other than the traditional gate theory or eidorphin theory, suggest
fetta asada, neuramenl stan, or table mit bend Randa
is also studied the effects of low-frequency TENS on uleer healing.“ te reports
TENS in labor and delivery has also been advocated by some clinicians, Adve

‘ages of TENS over conventional analgesies are similar to those noted in its use for
Bstoperatine nel notably, the Jack of potential risk that is associated with
Sal pain relief methods, including epidural anesthesi, local black

18. 1 Morey cite the following advantages: () is safe tooth
) les cas adminstered, and (4 iis ready
ped et IO a $294 aia ees
These electrode placement are based, in par, on research by Bonic from which he
Concluded that impulses fom uterine contraction and dilation of the cervix core medi
Stein aflerent nerve pahways rather than entering the sympathetic nerve distribution
SF T10_LL Pain impulses from distension and stretching af the delivery canal, pelvic
Moor, vla, and perineum reach the spinal cord vi the pudendal nerves and the dors
toot of $2-S4 :
‘Most ofthe research on TENS for labor and delivery has come fiom Europe
further studies are required to determine its place as an adjunctive therapy inthe
Birthing proces inthe United Sates

gesie/sedative drugs. Grim
mother and child, (2) it i m
reversible.” Electrodes are comm

;
}
|
|

CONTRAINDICATIONS TO TENS

Considering the widespread use of TENS, few contraindications exist in the clinical
5 wicated for patients with cardiac pacemakers. of the_syn-

chronous (demand) type. However, TENS may be safely administered to patients with
the asynchronous (fixed-rate) type of cardiac pacemaker.* Shealey and Maurer indicate

that the amount of transcutancously applicd current needed to produce

| fibrillation is substantially greater than that produced by any battery-operated TENS
unit Placement of TENS electrodes over the carotid sinus decontraindicated, as it has

been found to produce arzvthmia and bradycardia. Placement of TENS electrodes over

‘pregnant uterus remains controversial. The effect of electrode stimulation on the fetus

has not been determined: asthe safety of such electrode placement is questionable, it

should be avoided. Finally, electrode placement along the pharyngeal arca may hamper

breathing

| PLACEBO

ect is present in TENS treat
ble-blind study, Thorst coworkers found the placebo effect of
TENS to be approximately 30 percent, which is similar to that
state that many studies are not double-blind and therefore do
‘evaluate the placebo effect. Linzer and Long also found a significant placebo effec in

their chronic-pain-treatment program.2" Loeser stated that a placebo effect accounts for
a 3-percent success rate."

of medication.*? They
yt have the ability to

SUMMARY

Over the precedi
‘of controlling acute
without the

20 years, TENS has gained increased recognition as a viable means
nd chronic pain. The benefit of TENS is that it allows pain control
verse systemic effects of pain medications. TENS has the potential fr

19. K.M. C. LIBRARY

FERENCES