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Introduction to TENS

Shoulder Therapy

Why do we have pain?

Pain is the body's warning system. it alerts us to injury or illness. When the body is functioning normally, pain serves as a vital warning sign when something is not right. Without pain a person would not know when to get away from danger or to seek medical help.

Pain signals in the form of electrical impulses, travel through the body's nervous system from the site of the injury or ailment to the brain. Then, at the brain, these impulses are interpreted as pain.

What is TENS?

TENS stands for Transcutaneous Electrical Nerve Stimulation. Pain, whether chronic (long-term) or acute (short-term, often from surgery or trauma), can be relieved through a variety of methods including drugs, topical ointments, surgery, and electrical stimulation. A TENS device is a small battery-operated stimulator that generates low-intensity electrical impulses through the skin to stimulate the cutaneous (surface) and afferent (deep) nerves to help control pain. The device delivers these mild impulses through leadwires which are connected to electrodes, which then direct the signals through the skin at the appropriate pain sites on the body. TENS acts on the nervous system in different ways, depending on the type of frequency being delivered. Unlike drugs or topical ointments, TENS does not have any known side effects.

How does TENS control pain?

There are two major theories as to how electrical stimulation relieves pain. According to the "gate control theory" pain and non-pain impulses are sent to the brain from the local nervous system. These impulses travel through the cutaneous nerves to the deeper afferent nerves and then to the spinal cord and brain. Along the path are man areas referred to as "gates." These gates control which impulses are allowed to continue to the brain. The gates prevent the brain from recieving too much information too quickly. Since the same nerve cannot carry a pain impulse and a non-pain impulse simultaneously, the stronger, non-pain impulse (from the TENS device) "controls the gate," and basically over rides the pain signal, resulting in less pain perception.

According to the second theory, TENS stimulation encourages one's body to produce and release greater amounts of a chemical called endorphin. Endorphins are our body's own natural painkillers that are released as a natural function to overcome pain. Endorphins interact with pain receptors, blocking the perception of pain, much as the pharmaceutical drugs or narcotics such as morphine does, but without the side effects assosciated with these types of drugs.

TENS has no curative value; however, for many people who are suffering from pain due to an injury or ailment, the use of TENS can help manage their pain considerably. Pain sufferers who have not been able to find relief from drugs or who may have experienced uncomfortable side effects from drugs, may find TENS to be a great alternative in controlling the pain. In today's fast-paced lifestyle, many people just do not have the time to be set back due to pain. TENS devices can help them control and manage their pain, so that they may still be able to perform their daily functions at home or at work, return to work sooner, or perhaps enjoy more activities than they have before.

Advantages of TENS

There are a number of advantages of TENS which makes it appealing to both the clinician and the patient.

  • TENS is a non-invasive device.
  • It is portable.
  • TENS is user friendly and safe to be used by the patient at home. It therefore offers the patient a self-management option -- a desirable aspect of any treatment program since this has been shown to increase patient compliance and response to treatment.
  • After the initial cost of purchasing a TENS device, the replacement of batteries and electrodes are the main running costs. In long-standing cases of pain, this is cheaper than regular prescriptions for analgesics.
  • The precautions and contradictions assosciated with TENS are few and largely based on common sense. In addition, side-effects are minimal (i.e. skin irritation)
  • TENS is non-addictive.

How do I get a TENS device?

TENS devices are available only with a doctor's prescription. Once you have a prescription from your doctor or chiropractor, you can purchase a TENS device from your medical equipment distributor or pharmacy. Most insurance, including Work Comp and Medicare, will cover TENS devices.

Once TENS has been prescribed, your doctor, therapist, or distributor can instruct you on its proper use. With Medicare, a trial rental period of 30 days is required, then if it is beneficial, the doctor can request for purchase of the device. Most group insurance companies will cover the purchase of a TENS unit, but be sure to check your coverate, as every insurance policy is different.

Is TENS safe?

Yes. The thought of putting electricity into the body may seem a little scary at first, but all you feel is a mild tingling sensation under the electrodes. There are no known cases of electrical shock, and unlike some narcotic drugs that are prescribed for pain relief, TENS does not cause any dangerous side effects. The only reported side effects are occasional skin irritation at the electrode sites. TENS is a symptomatic treatment only, and as such, has no curative value.

Should I continue to take pain medication while using TENS?

You should discuss with your physician how the decreasing of pain medication should be correlated with your use of TENS In general, pain medication should not be decreased until you begin to experience relief, since the effectiveness of the TENS device cannot be accurately evaluated if you experience a sudden increase in pain resulting from complete medication withdrawl.

What do the TENS devices consist of?

Most TENS devices offer two channels so that you can treat two different areas at the same time. Each channel requires two electrodes (one is positive and one is negative to complete the circuit). TENS devices usually offer adjustable controls for the pulse rate (which determines how fast the pulses are coming out per second), the pulse width (which determines the length of each pulse measured in microseconds), and the amplitude, or intensity (which determines how strong the current is). Some devices offer various treatment modes which automatically vary the pulse patterns.

Most TENS units operate on a 9-volt battery. TENS units normally will come equipped with a battery, a set of leadwire cables, and a set of disposable or reusable electrodes.

Are TENS devices difficult to use?

Most TENS devices are simple to use. Your doctor or therapist will generally recommend what settings to use and where to position the electrodes on your body. Maintenance usually only requires replacing electrodes, batteries, or the leadwires.

How long must I wear the unit?

Treatments usually call for 30 minutes or as needed, but your doctor or therapist will instruct you as to the treatment regimen recommended for your condition, since each individual's needs are different.


Still want to learn more?

Download our "Introduction to T.E.N.S." brochure. It is a great resourse that provides detailed information about TENS, waveforms, and electrode placement. Ideally for the patient just getting started.

Introduction to TENS

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