It is the application of low frequency pulsed rectangular current through skin to reduce pain. A small battery machine is used to generate a current having specific stimulatory effect.

Parameters of TENS:

Pulse shape: Rectangular
Pulsed width: Measured in microseconds and often 100 μs or 200 μs
Pulse frequency: As low as 2 Hz and as high as 600 Hz but usually fixed i.e. 150 Hz.
Pulse intensity: Vary from 0 – 60 mA.
  1. High TENS: High frequency and low intensity
Frequency 100 – 500 Hz
Pulse width 100 – 500 μs
Intensity 5 – 30 mA
  1. Low TENS: Low frequency and high intensity
Frequency 1 -5 Hz
Pulse width 100 – 250 μs
Intensity more than 30 mA
Electrode placement:
  • Area of greater intensity of pain/near
  • Trigger or motor point

Advantages of TENS:

  • It is non – invasive, portable and non addictive.
  • It is cheaper than regular analgesics.
  • It has few contraindications and precautions
  • It has changeable battery and electrodes.
Disadvantages of TENS:
  • Number of patients fails to tolerate the electrical stimulation.
  • Skin irritation may occur due to allergic reaction.
  • Chemical burn is also a disadvantage of TENS.

Indications of TENS:

  • Chronic pain syndrome
  • Phantom limb pain
  • Reflex sympathetic dystrophy
  • Post operative conditions
  • Obstetric pain

Contra indications:

  • Continuous TENS may result some electrolytic reaction below the skin
  • Pacemakers
  • First three month of pregnancy
  • Hemorrhagic conditions
  • Open wounds
  • Carotid sinus
  • Over mouth
  • Near eyes

Treatment method:

A patient may have a single daily treatment of 40 min duration. Portal TENS can be used continuously for 24 hrs.

Modes of TENS:

a.    Conventional TENS:

It is the most commonly used mode of TENS. It can be used for both Acute and Chronic pain.
Mechanism of Action:
Stimulation of large diameter through pain gate control theory
  • Frequency 100 – 150 Hz
  • Intensity 12 – 30 mA
  • Pulse width 50 – 80 µs

b.   Acupuncture like mode:

Mechanism of Action:
The stimulation of small diameter nerve fibers to release endogenous opiods  
  • Frequency 1 -5 Hz
  • Intensity above 30 mA
  • Pulse duration 150 – 300 µs

c.    Burst mode:

This mode has characteristics of both high and low TENS. The pain control is through both routes.
  • Frequency 50 – 100 Hz but the frequency is delivered in packets of 1 – 4 Hz
  • Pulse duration of 50 – 100 µs
  • Intensity below 30 mA

d.   Brief intense TENS:

It has rapid onset but for short term. Clinician used it for wound debridment, joint mobilization and contracture.
  • Frequency 80 – 150 Hz
  • Pulse duration 50 – 250 µs
  • Intensity according to tolerance of patient