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1. TENS – Transcutaneous
Electrical Nerve Stimulator

2. INTRODUCTION
▷ Pain is man’s oldest enemy and for centuries, medicine has searched for an innocuous,
non-destructive, non-invasive, well tolerated and effective way of relieving pain that is both
efficient and practical.
▷ People feel pain when a signal travels through nerve fibers to the brain for interpretation.
▷ It is found that a therapy that uses low-voltage electrical current blocks the pathway of
transmission of pain, in order to provide pain relief.
▷ These electrical impulses seem to jam pain signals travelling along the nerve pathways
before they can reach to the spinal cord and brain.
▷ The same electrical impulses also stimulate the body to produce natural pain relievers
called endorphins and enkaphalins.
▷ The electrical impulses required for electrotherapy to relieve pain are provided by an
instrument called TENS.

3. ▷ TENS therapy has been used to relieve both chronic (long lasting) and acute (short-term) pain.
▷ TENS units may help treat the symptoms like neck and back pain, joint pain, post-operative
pain, myofascial pain, neuropathic pain, labor pain and period pain.
▷ Two types of waveforms are optimally and equally effective in relieving pain – square and
spike wave.
▷ Electrodes are placed at specific sites on the body for treatment of pain.
▷ The current travels through the electrodes and into the skin stimulating specific nerve
pathways to produce a tingling or massaging sensation that reduces the perception of pain.
Surface Paste-less electrodes /
Conducting pads
TENS

4. TENS DEVICE
▷ A TENS machine is a small, battery-operated device that delivers small electrical impulses
when the device is switched ON, with the help of electrodes.
▷ Typically the stimulator is based around a 500ms spike pulse, having an adjustable
amplitude of 0 to 75mA and an adjustable frequency of 12 to 100 pulses per second.
▷ Instruments having similar specifications except they
produce square waveform, have a pulse frequency range
of 20-200Hz, pulse width from 0.1 to 1.0ms and pulse
amplitude of 0-120V with maximum output current as
25mA.
▷ Instrument is powered by three standard flashlight
batteries of 1.5V each, gives about 100 hours of
continuous operation.

5. ▷ Transcutaneous or skin surface application of electrical stimulus
is accomplished by application of conducting pads to various trigger points,
acupuncture sites or even peripheral nerves.
▷ Skin irritation at the site of electrode application is diminished by the
use of carbonized rubber electrodes applied with a tincture of Benzoin
interface.
▷ The skin electrode system must be designed so as to minimize
impedance variations with motion.
▷ TENS electrodes are commonly molded from an elastomer such as silicon rubber, loaded with
carbon particles to provide conductance.
▷ Comformatibility is achieved by making electrode thin.
▷ A thin electrode may exhibit an impedance which is not negligible as compared to impedance
of the interface and tissue under it.
▷ Thus, the design of an electrode with the required comfortability and current distributing
properties become a compromise in electrode geometry and material properties.

6. TYPES OF CURRENT USED
Asymmetrical
Biphasic
Monophasic
Symmetrical
Biphasic
Spike

7. TECHNIQUES OF TENS APPLICATION
1. Conventional or High Frequency TENS: creates fast relief, may stop the pain-spasms cycle,
relief is short lived.
2. Acupuncture or Low Frequency TENS: activation of endorphins by suppression of pain
pathway, longer lasting pain relief however slower to begin. Frequency usually 1-5Hz and
Pulse Width 200-300µs.
3. Brief Intense TENS (hyper stimulation Analgesia): similar to high frequency TENS, highest
frequency is 100Hz and pulse width is 200µs. It’s intensity is very high but to the subject’s
tolerable level. Treatment time is 15mins.
4. Burst Mode TENS: similar to low frequency TENS, short series of pulses with high frequency
that are repeated at low frequency. Used for general chronic pain relief.
5. Modulated TENS: frequency varies between different settings and uses a cyclical to help
reduce nerve adaptation. Useful for acute and chronic pain relief.

8. TENS
Electrode
Placement

9. Implantable device
Such as defibrillator, bone
growth stimulator, etc. TENS
could cause these devices to
malfunction.
Pregnancy
TENS therapy should not be
applied to the abdomen, pelvic
area, lower back or to
acupuncture points.
Cancer
Not to apply electrodes to areas of
the body where there is known or
suspected cancer.
Epilepsy
If the patient has/had a history of
epilepsy, TENS impulses could
cause seizures.
Heart disease
TENS shouldn't be applied if the
patient has/had heart failure or
arrhythmias.
Deep Vein Thrombosis
TENS therapy may increase blood
circulation, which may increase
the risk of dislodging a blood clot.
CONDITIONS WHEN TENS THERAPY
SHOULDN’T BE USED

10. PROs
Portability
Non-Invasive
Easy to use at home
Immediate Effect
PROs AND CONs
CONs
Only treats the symptoms
of pain, it will not actually
treat what’s causing the
pain.
Doesn’t provides long term
solution, it is probably used
for short term.
10

11. Thank You !