Transcutaneous Electrical Nerve Stimulation (TENS)

By Dave Paris
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There are many therapeutic modalities available to treat musculoskeletal pain or spinal pain complaints, including low back pain. These modalities cover a wide range of treatments ranging from instruments, tools and machines used in treating these conditions. One of the most widely used categories of modalities are electrotherapeutic modalities. While there are many variations of electrotherapeutic modalities, the following 3 are considered the most common: transcutaneous electrical nerve stimulation (TENS), electrical muscle stimulation (EMS) and interferential current (IFC). In my experience, transcutaneous electrical nerve stimulation (TENS) is the most common, most accessible and easiest to use of the three. Read on for a description of TENS, the theory of how it works and brief overview of its evidence and any precautions or known harms from its use.

Transcutaneous Electrical Nerve Stimulation (TENS)

TENS, the most common term for this modality, uses an electrical current delivered through electrodes placed on the skin surrounding the affected area. This causes a tingling sensation and is believed to interrupt or disrupt the pain signals in the surrounding nerves. Generally, electrotherapeutic modalities have one or more of the following goals: reduce pain, reduce inflammation, increase movement thereby improving healing through increasing blood flow and stimulating nerves. While TENS is mainly considered for use in pain reduction it can be used for other purposes.

TENS Treatment Frequencies

If you are treated with TENS you will have pads placed around the affected area. Then the health care provider, or you (yes, TENS can be done at home!), will choose a high or low frequency. Frequency is simply how often something is happening per second and this measurement is called hertz (HZ). Low frequency for TENS is considered 5-10 HZ or 5-10 cycles per second. Low frequency TENS is thought to produce muscle contractions and pain reduction for hours. High frequency TENS (80-100 HZ) is believed to be mainly a counterirritant sensation and thus “block” pain signals. Once your particular setting is chosen, often based on patient preference, you will simply let it run for anywhere from minutes to hours if needed. Again, this is generally based on your preferences and individual needs.

Evidence For TENS

The evidence for TENS is mixed with most done on patients with chronic low back pain. In these patients there was some benefit noted for pain relief immediately after treatment. A well-respected and nationally-recognized research group, Cochrane Collaboration, did a large review in 2005 and concluded there was a lack of studies to make better recommendations.

Of note, there are some precautions but TENS is widely considered safe when precautions are taken. Those precautions are to not use TENS (or any electrotherapeutic modality) over the neck, chest, heart or head. Not to use over or near the stomach of a pregnant woman. Never use with implanted electrical devices, cardiac pacemakers or defibrillators, and for patients with venous or arterial thrombosis. As always, you should seek a health care professional’s guidance for assessment and treatment recommendations. They can guide you in the who, what, where and when for any interventions you might consider.

The Final Word On TENS?

In my opinion, there are subsets of patients where it helps what hurts. They’re relatively inexpensive, they’re easy to use, can be used at home and have very low risk. We haven’t yet truly identified a way to know who will respond and who will not or to what level of success they’ll get from using TENS. For TENS, ‘good’ success simply can be pain relief, ‘better’ would be improving function or activities and ‘best’ success would be both pain relief and functional improvement or return to work/life activities etc. Ultimately the goal is to have someone return to pain-free living without need for any treatment.