What is TENS FAQ

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TENS is an acronym for Transcutaneous Electrical Nerve Stimulation. Developed in

the late 1960's, the TENS stimulator is a battery-powered device which transmits

an electrical impulse through lead wires and surface electrodes to underlying

nerves. The stimulator converts the direct current of the battery into pulses of

stimulation. Most stimulators feature adjustable settings to control amplitude

(intensity) of stimulation by controlling voltage, current, and pulse width

(duration) of each pulse.

Electrodes are placed at specific sites on the body for treatment of pain. The

current travels through electrodes and into the skin stimulating specific nerve

pathways to produce a tingling or massaging sensation that reduces the

perception of pain.

When used as directed; TENS is a safe, non-invasive, drug-free method of pain

management. It is used to offer a better quality of life for people with pain.

Some common uses for TENS treatment are: acute and chronic pain, post op

incisions and post surgical pain, labor and delivery, migraine and tension

headaches, acute pain from sports and other injuries, arthritis, chronic pain

from tendonitis and bursitis, cancer pain, and wound healing.

The neurophysiological basis of the analgesic action of TENS remains under

investigation, yet there are two popular theories to explain how TENS

successfully decreases or eliminates pain.

Pain Gating

Electrical stimulation of your nerves can block a pain signal as they travel

from the site of injury to the spine and then upwards to the brain. When these

signals arrive at the brain we perceive pain. If they are blocked en-route to

the brain we do not perceive pain. This is known as 'closing the pain gate'.

When using TENS to 'close the gate' we use Continuous (or Conventional) Tens

Mode. Continuous TENS mode produces a gentle and pleasant 'tingling' under and

between the electrodes. The 'tingle' sensation helps to block the pain by

closing the 'pain gate' and slowing down the painful nerve signals - this

produces analgesia (numbness) in the painful area that can last for a few hours.

Pain 'Gating' is very simply described by using the example of when you " bump

your elbow " , and then rub it to ease the pain.

When your elbow is bumped, pain messages travel to your brain. Here the messages

are interpreted as " Pain " . Rubbing this same elbow vigorously will stimulate an

abundance of new " non-painful " messages to travel to the brain.

Luckily, your brain can only interpret a limited amount of information. If the

" rubbing " sensations outnumber the painful " bump " sensations, the brain will

interpret the sensations as being from the pain-free rubbing source rather than

the painful bump.

In other words, the rubbing sensations have 'bombarded the gate', so painful

messages cannot get through.

We all know from personal experience, the faster we rub our bumped elbow, the

better the results. Your TENS works in just the same way ... it's just rubs you

via an electrical stimulation instead. Plus, it doesn't get as tired!

TENS Stimulates an Endorphin Release

The body has its own built in mechanism for suppressing pain. It does this by

releasing natural chemicals called endorphins in the brain and spinal cord and

these chemicals act as very powerful analgesics.

When using TENS to help activate endorphins we use Burst TENS Mode. Burst mode

produces a rhythmic pulse which should be strong enough to produce a 'twitch' in

the muscles underneath the electrodes. This muscle 'twitch' helps to release the

endorphins and enkephalins and also helps the pain 'switches' in the brain to be

activated through muscular and reflex activity.

Endorphins are a naturally occurring hormone in the body. They are released in

response to an injury or physical stress to reduce your pain and promote a

feeling of wellbeing. Much like Morphine, and related medications, endorphins

have a similar chemical structure, which explains their strong painkilling

effects.

Example

A great example of endorphin release is the natural 'high' that runners and

other athletes experience after 30 minutes of sustained exercise. Much like

exercise, the endorphin release stimulated by the TENS may take up to 30 minutes

or more to take a noticeable effect. The " feel good " effect may last several

hours before endorphin levels in the body need to be increased again.

How does a TENS machine actually relieve your pain

In order for you to understand how pain is relieved by your TENS machine, you'll

need a basic understanding into what causes you to feel pain in the first place.

There are two types of pain:

a.. Somatic pain arising from the stimulation of receptors in the skin, muscle

joints and tendons and visceral pain arising from the stimulation of receptors

in the skin, muscle joints and tendons and

a.. Visceral pain arising from the stimulation of receptors in the viscera.

(Tortora and Anagnistakas, 1984)

How does your brain feel pain?

In general, pain receptors are classified according to their location (Carey,

1985). Receptors that respond to injury or noxious stimuli are termed

nociceptors and are sensitive to thermal (heat), electrical, mechanical,

chemical and painful stimuli. Each nociceptor is connected to a nerve that

transmits an electrical impulse along its length towards the spinal cord and

then, ultimately your brain. It is your brain that informs you whether or not

you are experiencing pain. (Hoskins and Welchew 1985).

Pain messages travels slower than other nerve stimulation

Nerves can also be categorized according to their diameter (width) and whether

or not a myelin sheath is present.

Fordham (1986) suggested that three types of nerves are concerned with the

transmission of pain.

a.. A beta fibres, which have a large diameter and are myelinated.

a.. A delta fibres, which have a small diameter and also have myelinated

sheaths.

a.. C fibres, which have small diameters and are non-myelinated (slowing their

conduction rate) and are generally involved with the transmission of dull,

aching sensations (Carey 1985).

Nerves with a large diameter conduct impulses faster than those with a small

diameter (Hoskins and Welchew 1985). The presence of a myelin sheath also

speeds up the nerve conduction rate.

Which nerve fibres do TENS effect?

TENS stimulates A beta fibres, the fastest and largest fibres. This means that

the " pleasant " messages provided by your TENS machine bombard the brain and

eliminate the much slower " painful " messages that travel via much slower and

smaller C fibres. The end result is that you no longer feel any pain.

It's that simple! TENS tricks your brain to relieve your pain.

Does TENS work for Chronic Pain?

Yes, TENS is very effective for the following reason:

Unfortunately the longer we have pain the better our body becomes at detecting

pain. If we can repeatedly break the habit of feeling pain, we can actually

" unlearn " the feeling of pain.

To achieve this unlearning reaction it is necessary to apply regular doses over

many weeks for long-term sufferers. The handy home TENS unit will help you to

break the chronic pain cycle or even stop it occurring in the first place.

How long does it take for TENS to work?

Your TENS unit provides both a release of endorphins and an effective " gating "

effect. The " gating " effect should be evident within a few seconds of

application.

As explained earlier, the endorphin release (and extended pain relief) may not

become apparent until after 30 minutes of application. Applications for more

than two hours will give maximum results.

A TENS can be worn safely for as long as required (including while sleeping -

although this could damage the leads of the unit).

Precautions

Please don't use a TENS if you have a pacemaker or during the early stages of

pregnancy. They can however be used during labour. Please check with your

obstetrician for their opinion prior to use.