Understanding Transcutaneous Electrical Nerve Stimulation
Transcutaneous electrical nerve stimulation (TENS) is mostly used to treat chronic pain conditions, such as osteoarthritis. Transcutaneous electrical nerve stimulation incorporates a small device that directs mild electric pulses to the nerves in or around the area being treated.
During treatment with transcutaneous electrical nerve stimulation, electrodes are placed or taped on the skin in the painful areas being treated. The electrodes are connected by a wire to a battery-powered stimulator. (Illustration)
Some TENS units work by blocking pain impulses via large nerve fiber stimulation. Other kinds of TENS work by causing the body to release endorphins (neurochemicals occurring naturally in the brain that have pain-relieving properties).
Transcutaneous electrical nerve stimulation can produce a tingling sensation at the site of the electrodes, but there generally are few side effects. While TENS can be done at home, instruction should be given by a physical therapist or doctor so the patient knows:
- how to position the electrode pads
- the correct electrical frequency and pulse strength to be used
- how long the treatment should last and how often it should be used
Studying the Effectiveness of Transcutaneous Electrical Nerve Stimulation
Several studies have analyzed the effectiveness of transcutaneous electrical nerve stimulation, primarily by comparing it to other modes of pain relief.
Acupuncture and TENS
A study published in February 2008 compared transcutaneous electrical nerve stimulation to acupuncture for knee osteoarthritis. There were just 32 patients with knee osteoarthritis randomly assigned to 4 groups in the study:
- acupuncture only
- TENS only
- acupuncture and TENS
- control group receiving a topical poultice (a type of compress)
Significant reduction in the intensity of pain and significant improvement in knee function was identified in the group using both acupuncture and TENS.
Intra-articular Hyaluronic Acid Injection v. TENS
In the March-April 2006 issue of Advances in Therapy, 60 patients with primary knee osteoarthritis were randomly assigned to one of two groups. In the first group, TENS was applied for 3 weeks. The second group had intra-articular hyaluronic acid injections once a week for 3 weeks. Patients were followed for 6 months.
Pain relief in both groups was apparent at the first month follow-up and lasted through the sixth month. Stiffness decreased significantly in the TENS group by the first month, but it wasn't until the sixth month that those in the injection group got the same benefit. Physical function assessments (ability to perform tasks) did not change for either group. Researchers concluded that the two treatments used in combination may be most beneficial for osteoarthritis symptoms.
Exercise Training v. TENS
Yet another study published in 2004 examined if the addition of transcutaneous electrical nerve stimulation to exercise training would produce better physical outcomes than either TENS or exercise alone in a group of knee osteoarthritis patients. There were 62 patients randomly assigned to 4 groups:
- TENS alone
- placebo stimulation
- exercise training
- TENS and exercise training
The treatments were used 5 days a week for 4 weeks. Researchers concluded that the addition of TENS to exercise training produced the best overall improvement in physical outcomes for the knee osteoarthritis patients.
Cochrane Review of TENS
A Cochrane Database Systematic Review of TENS for knee osteoarthritis was published in 2000. The review confirmed that pain relief from TENS was significantly better than placebo for knee osteoarthritis patients.
Study upon study seems to conclude that some knee osteoarthritis patients may successfully obtain pain relief from transcutaneous electrical nerve stimulation. It also seems clear that transcutaneous electrical nerve stimulation used in combination with other pain-relieving techniques may be the best approach for certain patients.
A pilot study on using acupuncture and transcutaneous electrical nerve stimulation to treat knee osteoarthritis. Chinese Medicine. February 2008. Itoh K et al.
Comparison of therapeutic efficacy of TENS versus intra-articular hyaluronic acid injection in patients with knee osteoarthritis. Advances in Therapy. March-April 2006. Paker N et al.
Transcutaneous electrical nerve stimulation for knee osteoarthritis. Cochrane Database Systematic Review. 2000;(4):CD002823. Osiri M, Welch V, Brosseau L, Shea B, McGowan J. Tugwell P, Wells G.
Would the addition of TENS to exercise training produce better physical performance outcomes in knee osteoarthritis than either alone? Clinical Rehabilitation. August 2004. Cheing GL, Hui-Chan CW.