TENS

1
TENS

• Transcutaneous Electrical Nerve Stimulation

2
Mechanism of Action

• TENS is a method of electrical stimulation which
  primarily aims to provide a degree of symptomatic
  pain relief
• by exciting sensory nerves and thereby
  stimulating either the pain gate mechanism and/or
  the opioid system.
• The different methods of applying TENS relate to
  these different physiological mechanisms.
• The effectiveness of TENS varies with the
  clinical pain being treated,

3
General concept

• An Approach to pain control
• Trancutaneous Electrical Nerve Stimulation
• Any stimulation in which a current is applied
  across the skin to stimulate nerves
• 1965 Gate Control Theory created a great
  popularity of TENS
• TENS has 50-80 efficacy rate
• TENS stimulates afferent sensory fibers to elicit
  production of substances such as endorphins,
  enkephalins and serotonin (i.e. gate theory)

4
Introduction

• The TENS unit has now become a popular modality
  for patients because it is easy to operate and
  use.
• you should be familiar with the basic use and
  the special precautions for this modality.
• In this lecture, we will discuss another
  physical therapy modality called Transcutaneous
  Electrical Nerve Stimulation

5
Introduction

• Research would suggest that when used well it
  provides significantly greater pain relief than a
  placebo intervention.
• There is an extensive research base for TENS in
  both the clinical and laboratory settings and
  whilst this summary does not provide a full
  review of the literature.
• .

6
Introduction

• It is worth noting that the term TENS could
  represent the use of ANY electrical stimulation
  using skin surface electrodes which has the
  intention of stimulating nerves.
• In the clinical context, it is most commonly
  assumed to refer to the use of electrical
  stimulation with the specific intention of
  providing symptomatic pain relief

7
Apparatus of TENS
8
Principles of the TENS Unit

• Transcutaneous electrical nerve stimulation
  (TENS) is a valuable clinical procedure for the
  symptomatic relief of pain.
• The TENS unit consists of a small pulse voltage
  generator source, interconnecting lead
  wires/cables, and electrodes.
• This allows a patient to self-administer modul
  electrotherapy,
• It is about the size of a portable cassette
  player, which can be worn on a belt around the
  waist.

9
Principles of the TENS Unit (cont'd)

• An individual applies a conduction medium (gel)
  to electrodes, which are then applied to the skin
  at appropriate peripheral nerves.
• Low-voltage electrical impulses travel through
  the skin to the underlying tissue to act as
  stimulus.
• The impulses help block the bodys ability to
  send a pain message to the brain.
• Increases the bodys ability to produce its own
  pain killing substancesphysiologically induced
  endorphins

10
Principles of the TENS Unit (cont'd)

• Various placement techniques have been
  identified
• Contiguous Placementmost common placement
  technique.
• It involves placing the electrodes alongside the
  area of localized pain, to direct the flow of
  current through or around the area of pain.
• Have the patient identify the area of greatest
  pain. In a circular motion, use your fingers to
  locate the muscle spasm.

11
Principles of the TENS Unit (cont'd)

• Place the electrodes in a circle approximately
  610 inches from the central point of pain.
• Motor, trigger, and acupuncture pointsPlace one
  pad directly over the point.
• Complete the circuit by placing the second pad on
  some area on the affected side.
• This second electrode site can be within a nerve
  zone or a master point such as an acupuncture
  point (L1

12
Specification of TENS
13
Specification of TENS

• The current intensity (A) (strength) will
  typically be in the range of 0 - 80 mA, though
  some machines may provide outputs up to 100mA.
  Although this is a small current, it is
  sufficient because the primary target for the
  therapy is the sensory nerves, and so long as
  sufficient current is passed through the tissues
  to depolarise these nerves, the modality can be

14
Specification of TENS

• The machine will deliver discrete pulses of
  electrical energy, and the rate of delivery of
  these pulses (the pulse rate or frequency (B)
  will normally be variable from about 1 or 2
  pulses per second (pps) up to 200 or 250 pps
  (sometimes the term Hertz or Hz is used here). To
  be clinically effective, it is suggested that the
  TENS machine should cover a range from about 2
  150 pps (or Hz).

15
Specification of TENS

•  In addition to the stimulation rate, the
  duration (or width) of each pulse (C) may be
  varied from about 40 to 250 micro seconds (ms).
  (a micro second is a millionth of a second).
  Recent evidence would suggest that this is
  possibly a less important control that the
  intensity or the frequency and the most effective
  setting in the clinical environment is probably
  around 200ms.

16
Specification of TENS

• most modern machines will offer a BURST mode (D)
  in which the pulses will be allowed out in bursts
  or trains, usually at a rate of 2 - 3 bursts
  per second. Finally, a MODULATION mode (E) may be
  available which employs a method of making the
  pulse output less regular and therefore
  minimising the accommodation effects which are
  often encountered with this type of stimulation.

17
Specification of TENS

• Most machines offer a dual channel output - i.e.
  two pairs of electrodes can be used
  simultaneously. In some circumstances this can be
  a distinct advantage, though it is interesting
  that most patients and therapists tend to use
  just a single channel application. Widespread and
  diffuse pain presentations can be usefully
  treated with a 4 electrode (2 channel) system, as
  can a combined treatment for local and referred
  pain

18
Transcutaneous Electrical Nerve Stimulation (TENS)

• TENS as a treatment technique is non invasive and
  has few side effects when compared with drug
  therapy.
• The most common complaint is an allergic type
  skin reaction (about 2-3 of patients) and this
  is almost always due to the material of the
  electrodes, the conductive gel or the tape
  employed to hold the electrodes in place.
• Most TENS applications are now made using self
  adhesive, pre gelled electrodes which have
  several advantages including reduced cross
  infection risk,

19
TENS

• Indications
• Control Chronic Pain
• Management post-surgical pain
• Reduction of post-traumatic acute pain
• Precautions
• Can mask underlying pain
• Burns or skin irritation
• prolonged use may result in muscle spasm/soreness
• caffeine intake may reduce effectiveness
• Narcotics decrease effectiveness

20
Biophysical effect

• Primary use is to control pain through Gate
  Control Theory
• (between 0-100 can be placebo effect )
• Opiate pain relief through stimulation of
  naloxone (antagonist to endogenous opiates)
• May produce muscle contractions
• Various methods
• High TENS (Activate A-delta fibers)
• Low TENS (release of ??-endorphins from
  pituitary)
• Brief-Intense TENS (noxious stimulation to active
  C fibers)

21
Techniques of TENS application

• Conventional or High Frequency
• Short Duration , high frequency and low to
  comfortable current amplitude
• Only modulation that uses the Gate Control Theory
  (opiate all others)
• Acupuncture or Low Frequency
• Long pulse duration, Low frequency and low to
  comfortable current amplitude

22
Techniques of TENS application

• Brief Intense
• Long pulse duration, high frequency, comfortable
  to tolerable amplitude
• Burst Mode
• Burst not individual pulses, modulated current
  amplitude
• Modulated
• Random electronic modulation of pulse duration,
  frequency and current amplitude

23
Protocol for Various Methods of TENS
24
Conventional Tens/High Frequency TENS

• Paresthesia is created without motor response
• A Beta fibers are stimulated to enkephlin
  interneuron (pure gate theory)
• Creates the fastest relief of all techniques
• Applied 30 minutes to 24 hours
• relief is short lives (45 sec 1/2 life)
• May stop the pain-spasms cycle

25
Application of High TENS

• Pulse rate high 75-100 Hz (generally 80),
  constant
• Pulse width narrow, less than 300 mSec generally
  60 microSec
• Intensity comfortable to tolerance

26
Low Frequency/Acupuncture-like TENS

• Level III pain relief, A delta fibers get Beta
  endorphins
• Longer lasting pain relief but slower to start
• Application
• pulse rate low 1-5ppx (below 10)
• Pulse width 200-300 microSec
• Intensity strong you want rhythmical
  contractions within the patients tolerance

27
Burst Mode TENS

• Carrier frequency is at a certain rate with a
  built in duty cycle
• Similar to low frequency TENS
• Carrier frequency of 70-100 Hz packaged in bursts
  of about 7 bursts per second
• Pulses within burst can vary
• Burst frequency is 1-5 bursts per second
• Strong contraction at lower frequencies
• Combines efficacy of low rate TENS with the
  comfort of conventional TENS

28
Burst Mode TENS - Application

• Pulse width high 100-200 microSec
• Pulse rate 70-100 pps modulated to 1-5 burst/sec
• Intensity strong but comfortable
• treatment length 20-60 minutes

29
Brief Intense TENS - Application

• Pulse width as high as possible
• Pulse rate depends on the type of stimulator
• Intensity as high as tolerated
• Duration 15 minutes with conventional TENS unit.
  Locus stimulator is advocated for this treatment
  type, treatment time is 30 seconds per point.

30
Locus point stimulator

• Locus (point) stimulators treatment occurs once
  per day generally 8 points per session
• Auricular points are often utilized
• Treat distal to proximal
• Allow three treatment trails before efficacy is
  determined
• Use first then try other modalities

31
Electrode Placement

• May be over the painful sites, dermatomes,
  myotomes, trigger points, acupuncture points or
  spinal nerve roots.
• May be crossed or uncrossed (horizontal or
  vertical)

32
Contraindications

• Demand pacemakers
• over carotid sinuses
• Pregnancy
• Cerebral vascular disorders (stroke patients)
• Over the chest if patient has any cardiac
  condition

33
Indications for use

• Relief of acute pain
• Treatment of chronic painnoninvasive,
  non-addictive. Allows the individual to carry out
  normal personal and occupational activities
  comfortably.
• Locating electrode sitesmost critical factor
  that can influence the success rate and benefit
  from TENS is the proper placement of electrodes

34
Principles of the TENS Unit

• Dermatomes, Myotomes, and SclerotomesRegions of
  the body enervated by one spinal nerve.
• Electrode placement involves both stimulating
  across the similarly enervated area and/or
  placing an electrode (or set of electrodes) at
  the pain site.
• Set another electrode at the point where the
  nerve root joins the spinal cord.
• . The physician may not specify the exact
  location for the electrode sites
• You must try various styles of electrode
  placement to find which method best fits the
  needs of the individual patient.
• Patient input may be necessary to determine
  placement.

35
Principles of the TENS Unit

• Once acceptable placement has been achieved,
  record on the patients chart and reference sheet
• Exact placement of the electrodes.
• Setting so the patient can easily continue
  treatment at home.
• Take note of the direction of the current flow
  between electrodes.
• With a single channel (two-pad) application,
  there is no problem since current will always
  flow through the tissue from one single electrode
  to the other (Red against Black).
• If a patient has more than one affected area, the
  TENS unit may be rotated to the area needing the
  most relief.

36
Dermatomes
37
Dermatomes
38
Dermatomes
39
Settings of the TENS Unit

• Close monitoring of the patient is required. If
  the patient complains that the stimulation is
  uncomfortable, reduce intensity and/or cease
  stimulation. Note patients complaints and
  settings and inform the physician or physical
  therapist.

40
Settings of the TENS Unit

• Parameter ControlsThe TENS device has three
  controls.
• Intensity (Pulse Duration) control
• Used to set the degree or amount of impulse to be
  delivered.
• Each patient responds differently to the levels
  of intensity because of tissue resistance,
  enervation, skin thickness, etc.
• Frequency (Pulse Rate) control
• How rapidly or close together the impulse is
  delivered.
• The pulse frequency (Hertz or pulses per second)
  chosen depends greatly upon the type of electrode
  placement.
• Pulse Duration (Pulse Width)
• Longer pulse durations are needed to stimulate
  motor fibers.
• Shorter pulse durations are used on the more
  sensory fibers

41
Settings of the TENS Unit (cont'd)

• Patient Education
• Allow the patient to experience TENS output on a
  noninvolved area of the body.
• Always have the patient practice using the unit
  on himself in the office before he tries it at
  home.
• Patient can understand what the TENS stimulation
  is like and how the various controls function.
• Helps eliminate patients fears about being
  shocked by an unfamiliar electronic device.
• The therapist or physician should perform some
  type of pre- assessment.
• This serves as an index from which to show the
  patients progress.

42
Settings of the TENS Unit (cont'd)

• Patient Education
• Instruct the patient on how to use the unit. How
  to remove and install batteries and how to charge
  the batteries.
• How to use the electrodes remind the patient
  that the intensity control should always be at
  zero before electrodes are placed on the skin,
  removed, and/or their position is changed.
• Some electrodes are conductive on one side only.
• .

43
Settings of the TENS Unit (cont'd)

• The entire electrode surface should be covered
  with gel.
• If the electrodes are in place for three hours or
  longer, the gel should be checked for drying.
• If gel has dried even slightly, the electrodes
  should be removed, electrodes and skin washed,
  and the gel replaced.
• Emphasize that complete and firm electrode
  contact is necessary throughout the treatment

44
Settings of the TENS Unit (cont'd)

• Patient Education (cont'd)
• Tell the patient how long the treatment time
  should be and how often he should treat himself.
• Teach the patient how to locate the pain centers
  and where to attach the electrodes and connect
  the unit.
• Inform the patient of the precautions Remind the
  patient to always set the controls to zero before
  attaching or removing the unit. If the level area
  is not at zero, it may cause a sudden impulse
  which could cause the patient pain, discomfort,
  or damage to the affected are.
• Once the electrodes are in place, begin to adjust
  the levels to provide the maximum comfortable
  stimuli.

45
Settings of the TENS Unit (cont'd)

• Precautions and Warnings
• Provide the patient with written instructions and
  electrode sites on a Reference Sheet so the
  patient can easily continue treatment at home.
• Ask the patient to repeat the instructions to
  ensure an understanding of the procedure using
  the echo technique.
• Remind the patient not to wear the unit in or
  near water (shower, bath, or swimming TENS should
  not be used by patients wearing cardiac
  pacemakers, or by patients with a history of
  severe cardiac problems.

46
Settings of the TENS Unit (cont'd)

• Patient Education (cont'd)
• Such patients should consult their cardiologist
  before beginning any form of electrical therapy.
• Avoid placing electrodes near the heart.
• Avoid placing electrodes over the laryngeal
  muscles (throat). This could result in a muscular
  spasm which could block the airway to the lungs.
• TENS therapy should be avoided during pregnancy.
  The effects of long term electrical stimulation
  on the fetus are not known.
• Do not stimulate over the eyes, over the carotid
  sinus, or through the brain.
• There have been reports of skin irritation at the
  electrode site of patients using TENS devices.

47
Settings of the TENS Unit (cont'd)

• Do not put the electrodes on open wounds.
• Do not drop the unit.
• Do not immerse the unit in any liquid.
• Keep out of reach of children and do not use the
  unit on anyone else including members of the
  family.
• Patients should avoid operating heavy machinery
  or hazardous equipment while using TENS.
• Always check for the proper operation, batteries,
  and wiring of the TENS device.

48
(No Transcript)