The use of TENS continues to be a popular choice as front-line therapy, as adjunctive therapy, and when all else fails. There is a favorable benefit/risk ratio, if for no other reason than the risk to the patient is minimal to nil. The provider can control the key parameters of frequency, intensity, and pulse width. A TENS session is unlikely to cause adverse effects, and the strength of the current is controlled by the patient at all times. This form of treatment works well when the goal is to interrupt a pain/spasm cycle, which in itself might be a worthwhile endeavor and an important factor in preventing the hardwiring (centralization) of pain in the CNS. The most powerful evidence to date supporting the validity of TENS is that of functional MRI. Studies using evoked potentials also supported TENS efficacy by showing that TENS stimulation suppressed A-delta fiber nociceptive processing (gate control).
Ease of Treatment
The TENS treatment protocol is simple and forms the basis for application of the other electrotherapy devices, which tend to have a more elaborate set up than a TENS device. The basic analogue units (non digital) continue to be very useful for home care regimens, especially for patients who find complicated instructions and memory tasks challenging.
TENS treatments are relatively comfortable, and the devices can be worn during the course of a regular workday, with many patients being unaware that the units are even turned on most of the day. When patients are selected properly, the greatest operational drawback of TENS application is that of accommodation or tolerance, whereby a few minutes into the stimulation, the intensity of the current will need to be increased.
There have been numerous systematic reviews performed using various databases and the response results have been mixed. Arguably, the more important research was cited previously, including functional MRI and brain evoked potential studies that support the use of TENS application for suppressing cortical A delta activity in the parts of the brain involved in pain processing.