26/09/2023
Transcutaneous electrical nerve stimulation, known by its acronym TENS, is a modality that uses electric current to activate nerves in order to decrease pain. The TENS unit is a small device, often battery-operated, which can sometimes even fit into a pocket. It utilizes electrodes placed on the skin and which connect to the unit via wires to address pain in a target region. Pregnancy, epilepsy, and pacemaker are all contraindications for TENS. This activity describes the indications, contraindications, and clinical significance of transcutaneous electrical nerve stimulation and highlights the role of the interprofessional team in the management of pain.
Objectives:
• Summarize the indications for transcutaneous electrical nerve stimulation.
• Explain how transcutaneous electrical nerve stimulation reduces pain.
• Recall the complications of transcutaneous electrical nerve stimulation.
• Discuss interprofessional team strategies for improving care coordination and communication to advance the control of pain and improve outcomes.
Introduction:
Transcutaneous electrical nerve stimulation, known by its acronym TENS, is a modality that uses electric current to activate nerves for therapeutic reasons. The TENS unit is a small device, often battery-operated, which can sometimes even fit into a pocket. It utilizes electrodes placed on the skin and which connect to the unit via wires to address a targeted therapeutic goal. The units are said to be titratable, permitting for a high degree of user tolerance with few side effects. Compared to many medications, the device is free from the risk of overdose. TENS units are often highly adjustable, allowing the user to control pulse width, intensity, and frequency. Low frequency of < 10Hz in conjunction with high intensity is used to produce muscle contractions. High frequencies of > 50 Hz are used with low intensity to produce paresthesia without muscle contractions. Overall, the concept of TENS throughout history has been the topic of vigorous debate within scientific circles in regards to efficacy. However, while this modality of pain management has proven itself in clinical investigations, there remains to this day disagreement over which pain syndromes and conditions TENS is appropriate.
Indication:
The fundamental indication for TENS is seeking to manage pain, both acute and chronic. There is an overall divide across scientific literature regarding the efficacy of TENS application for particular types of pain or pain conditions. While a significant body of work exists which suggests that TENS is effective for neuropathic, nociceptive, and musculoskeletal pain, a notable portion of these studies were noted for methodological concerns.
A look at the three types of TENS is outlined below along with their conceptual indications.
Intense TENS is used primarily as a "counter-irritant." Aiming to target small diameter, high threshold cutaneous afferent (A-delta), this type of TENS specifically seeks to block transmission of nociceptive information in nerves while stimulating other analgesic mechanisms. Both high frequencies and intensities are used for short periods of time.
Contraindications:
Pregnancy, epilepsy, and pacemaker are all contraindications for TENS. Additionally, contraindications exist to the placement of the electrode pads in certain areas. Some of these placements include: over the eyes, trans-cerebrally, the front of the neck, simultaneously positioned anterior and posterior chest electrodes, internally, over broken skin or lesions, over tumors, directly over the spine, regions of severe paresthesia where the user might not recognize skin irritation
Technique Or Treatment:
It is imperative to read the manufacturer's instruction booklet, as each unit might have slight variances in recommendations. TENS units are now small and lightweight. Patients can place them in their pocket, on a desk, or hold them. Treatment sessions can take place at the convenience of the patient except while operating heavy machinery, driving, bathing, showering, or swimming. The unit should be powered off before placing the pads. Electrode pad placement is at least 1 inch apart in the appropriate dermatomal region of the targeted pain. The skin underlying pad placement must have intact sensation. After powering on the unit, the setting titration is to manufacturer recommendations. Red and black lead placement have little impact on clinical outcomes
Complications:
Overall, for the vast majority of people, TENS is believed to be safe and well-tolerated with little to no side effects. However, manufacturers of TENS units universally warn individuals with pacemakers, epilepsy, or are pregnant that these conditions are contraindications to use as they can lead to potential complications. Nevertheless, this has been viewed as more of a medico legal maneuver in high-risk populations, and TENS units are actually usable in these groups assuming close medical supervision and electrode placement is not in close vicinity to the chest, neck, or abdomen.
Furthermore, there have been some complications with impacting transdermal drug delivery systems if drug application is close to the TENS electrodes.
There have been documented dermatologic complications from using TENS units — the most of these cases relate to either allergic reactions to the electrode pads or contact dermatitis. Special hypoallergenic electrode pads are available for this population. Additionally, syncope and nausea have both been documented as complications of transcutaneous electrical nerve stimulation.
