Transcutaneous electrical nerve stimulation (TENS), a technique used by OTs and PTAs, can help patients manage pain during rehabilitation.
By John V. Rider PhD, OTR/L MSCS, CPAM CEAS
Transcutaneous electrical nerve stimulation, or TENS, is a non-pharmacological approach that can help patients manage their post-surgical pain during rehabilitation.
Post-surgical Pain
Nociceptive pain is caused by actual or threatened damage to non-neural tissue and is due to the activation of nociceptors (eg, soft tissue damage after an incision). Nociceptive (or non-neuropathic) pain is caused by actual or threatened tissue damage and is triggered by the activation of nociceptors.
In addition to incision-site discomfort, stretching, contusions or inflammation of the nerves can cause significant post-surgical neuropathic symptoms. In surgical cases, over 85% of patients experience post-surgical pain. 75% of these patients describe the pain as moderate to severe during the immediate postoperative phase.
4 Therapists can use TENS not only to combat post-surgical discomfort, but also to increase engagement in therapy, and improve post surgical rehabilitation outcomes.
Electrotherapy
Electrotherapy is not a new concept. Electric currents have been used to relieve pain since before electricity was discovered. In fact, the use of electrical currents to relieve pain dates back to the Egyptian Fifth Dynasty (2500 BC). Battery-powered TENS devices became available in 1919. These technological advances can be used by physical and occupational therapists to help their patients manage post-surgical discomfort.
Post-Surgical Benefits
It has also been shown that its use reduces analgesic consumption and associated side effects. Its use is also shown to reduce the consumption of analgesics and the associated side effects. 5
Conventional TENS and general guidelines
The literature has used the term “TENS”, but it is inconsistent and loose, leading to confusion amongst clinicians and patients. This inconsistent use can also lead to misunderstandings and misuses of TENS. TENS is defined as any technique that delivers electrical current across the intact skin surface to activate nerves 7. However, when discussing TENS in literature or with clinicians, they tend to refer to the “conventional” definition. Conventional TENS is a widely used TENS technique that is used to control pain. While parameters may vary between devices and in the literature, conventional TENs typically use low intensity (meaning that it causes paresthesias but does not increase pain), high frequency (generally 50 to 100 Hz), small pulse width (typically 50 to 200ms), and high frequency.
TENS can be used alone or in conjunction with skilled therapy. TENS, for example, can be used as a preparatory treatment to manage pain prior to skilled therapy. It can be used during therapeutic activities, occupational engagement or exercises to reduce pain. TENS can be used to address pain following therapy. TENS is a safe and effective treatment for post-surgical discomfort. Occupational and physical therapists are able to use it in a variety of ways during rehabilitation in order to reduce pain and increase patient engagement. TENS can be incorporated as part of a patient’s self-management plan for pain.
Electrode Placement
For conventional TENS, electrode placement is usually on the outer margins. Electrodes can be placed around the surgical site margins or in other areas where there is reported pain. Electrodes are usually placed approximately 5 cm either side of the suture to reduce the risk of damaging the incision.
It may seem difficult at first, but remember that electrode placement is often repositioned, and that therapists must follow the patient. The intensity of the current applied is dependent on a person’s tolerance. It may need to be adjusted often for optimal pain relief. Increase the intensity slowly until the patient reports decreased pain and feels “strong, but comfortable” paresthesias. If necessary, turn off the unit, reposition it, and then test again. Qualitative research conducted with patients who use TENS suggests that therapists introduce TENS in a learning phase to allow patients to maximize its use. 9 Patients may need to adjust the TENS settings over time and personalize the electrode placement. It may take some time and occasional adjustments to find the best electrode placement.
Most TENS units are easy to use and come with instructions in layman’s terms. Some electrical stimulation units used in rehabilitation settings have multiple channels and waveforms. This allows for more advanced customization. When using a single-channel, you can place the electrodes on the opposite sides of the outer edges of the painful area. The choice of horizontal or vertical placement is determined by the location of the pain and the tissue that has functional sensation. Dual-channel TENSs with two pairs electrodes are recommended for larger areas. The outcome can be unpredictable and can vary depending on the device manufacturer. The black lead is usually the active electrode, which will stimulate neural tissue. It should be placed over the peripheral nerve that needs to be stimulated.
The therapist should be aware of the benefits of different electrode placements. However, the best way to proceed is to discuss with the patient what works best for them, within safe parameters. The same general rule is applicable to intensity, pulse width, and frequency. When determining the duration, consider how this modality will be used. When used before or after therapy to relieve pain, the recommended duration is usually 30 minutes. TENS may be used for longer periods of time during therapy or when engaging in an activity. Explore effectiveness with the patient, and remember that TENS pain relief can vary. Patients may choose to use the device multiple times during the day.
Safety Considerations
In some cases, TENS can be used to treat unrelated pain if it is applied far enough away from affected area. 1 Do not use TENS next to transdermal drug administration because the currents could interfere. Before using TENS, the therapist should inspect the skin to make sure it is healthy, sensitive, and to check for any irritation. When TENS adverse reactions do occur, they are usually minor skin irritations.
How Will my patient respond to TENS?
Unfortunately, no factors have been identified to determine whether an individual will respond well to TENS. It may be helpful to let the patient try TENS before surgery in order to gauge their response. Some patients may be nervous about electrotherapy while others dislike the sensation. Truthfully, TENS is not for everyone. For all these reasons, therapists must give patients the opportunity to safely try TENS as part their pain management plan.
To achieve this, therapists must always perform a comprehensive evaluation before using TENS. They should also provide specialized education and training. Therapists can educate patients about the neurophysiology behind pain, tissue healing and graded exposure. They can also provide training on how to use the TENS unit safely and correctly. Therapists can use teach-back techniques to ensure patient understanding.
Comprehensive Pain Management
TENS is a very effective modality to treat post-surgical pain. However, it is only one part of the puzzle. Pain management should be approached from a multimodal perspective, using an interdisciplinary team. The therapists should consider adding additional evidence-based interventions to TENS in order to take a holistic approach for post-surgical pain and long-term carryover.
Therapists can help patients develop a plan for self-management of pain and implement selfregulation interventions, such as sensory reeducation and desensitization. They can also provide pain neurology education, explore pain coping techniques, utilize other physical agents, practice activity pacing, mindfulness, or use virtual reality. Pain is a complex issue, and it is always an individual experience. Therapists should respect the unique pain experience of each patient throughout the rehabilitation process.
Conclusion
Conventional TENS is a non-invasive, inexpensive, safe, and easy-to-administer modality that can help address post-surgical pain with minimal side effects. Current evidence suggests that it is effective at reducing post-surgical pain and reducing analgesic consumption when used appropriately.1,6,10 It is important to provide clear, simple instructions for the safe use of TENS as patients may continue to use it outside of therapy or after discharge. Lastly, therapists should use TENS intentionally and within a biopsychosocial approach to pain management alongside other evidence-based pain management interventions. Depending on the evaluation and the needs of the patient, therapists can utilize TENS to manage pain in preparation for therapy, during therapy, while engaging in meaningful activities, after therapy, or as part of a pain self-management program throughout the patient’s daily routine.
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