TENS machines should not be used if you have heart conditions, are wearing a pacemaker, have skin conditions like shingles or cancer, or suffer from epilepsy. Please consult your physiotherapist first to make sure TENS is safe for you.
Patients should be encouraged to experiment with various TENS settings until they find one that best meets their needs.
Low frequency
Low frequency signals use an alternating current low enough to penetrate skin layers and reach impulse fibers that suppress pain transmission to the spinal cord, with minimal potential for discomfort and wearable intensity settings that are user adjustable. As its name implies, low frequency devices have been successfully utilized by multiple studies for treating chronic back pain, fibromyalgia, and osteoarthritis of the knee.
These signals can be broadcast directly over a treatment area with electrode pads that adhere to the skin, using an alternating current that passes through them and generates mechanical vibrations in tissues below, producing a kneading action which alleviates muscle tension and stiffness, stimulating endorphin release.
Tens therapy has proven its efficacy in relieving some forms of pain; however, its impact in dealing with diabetic peripheral neuropathy remains unstudied formally yet. Research is in progress however.
Investigators conducted a randomized cross-over trial on 75 patients with type II diabetes mellitus and lower limb painful distal axonal neuropathy to test the effects of different TENS frequencies on pain intensity. Participants completed validated questionnaires such as the Brief Pain Inventory, Pain Disability Inventory, and Pain Catastrophizing Scale; daily pain assessments were recorded by participants as well as weekly phone interviews with researchers; quantitative sensory testing (QST) was then utilized to establish pressure pain thresholds and temporal summation of pain.
Both high-frequency TENS and low-frequency TENS were shown to significantly reduce pain intensity among young participants at baseline, immediately after, and 30 minutes post TENS application; however, no significant difference could be observed among the three TENS treatments among older participants.
Studies conducted on both HF and LF TENS showed similar effects when applied over the lumbar spine in another study, as well as reduction of activity in primary somatosensory cortices and increased connectivity between these regions of the brain. A more recent investigation involving healthy participants also demonstrated this.
The key takeaway from this analysis is that not all TENS devices are created equal. Being aware of the differences among these five signals will enable healthcare providers to select one with optimal functionality for their patient populations.
Intermediate frequency
TENS can create analgesia by activating endogenous inhibitory mechanisms in the central nervous system such as opioid, GABA, serotonin and muscarinic receptors. Which receptors are utilized depends on TENS frequency; for instance HF TENS produces analgesia by increasing concentrations of opioid b-endorphins in cerebrospinal fluid and can be blocked using naloxone to decrease this effect; in contrast LF TENS creates analgesia by activating NMDA receptors located throughout spinal cord neurons which again can be blocked using blockade of these NMDA receptors with blockade of those receptors using blockade of those receptors with naloxone to avoid oversaturation or over stimulation of these effects resulting in pain reduction; both effects can be prevented using blockade of these specific receptors to reduce pain levels without increasing opioid b-endorphin concentration, while blockade of opioid receptors can prevent oversaturation, for instance HF TENS produces analgesia by increasing concentration of opioid b-endorphin b-endorphin concentration and in human cerebrospinal fluid for humans while blockade of opioid receptors using naloxone. In contrast, LF TENS produces analgesia by activation of spinal cord NMDA receptors using similar techniques that blockage with naloxone.
TENS has been shown to reduce pain for patients suffering from musculoskeletal conditions like low back and neck pain as well as fibromyalgia; however, its efficacy against other painful conditions such as rheumatoid arthritis or knee osteoarthritis remains uncertain due to poor quality studies or heterogeneous interventions/comparisons/outcomes.
Recent research demonstrated the efficacy of TENS therapy for treating chronic cough. The research compared two groups, one using daily TENS while the other did not; patients using regular FS-TENS treatments experienced greater improvement than their counterparts who only utilized TENS occasionally.
Another study analyzed the efficacy of TENS in treating chronic shoulder pain. They compared results of two systematic reviews on its use for treating rotator cuff impingement and adhesive capsulitis with those from two small studies that employed TENS without adequately comparing its benefits against alternative therapies. Both reviews concluded there was insufficient evidence supporting its use; most importantly they concluded there was limited participation with few participants taking part.
TENS is not recommended for patients with implanted electronic devices such as pacemakers. However, under carefully controlled circumstances it may still be used. Many MSK solutions utilize TENS in their care models; however, evidence supporting its efficacy remains limited due to studies only focusing on chronic low back pain rather than other musculoskeletal conditions. It is essential that its clinical validity be supported by quality research studies that provide validated patient outcomes.
High frequency
HF TENS utilizes monophasic pulses at 100Hz with an amplitude range of 1–20mA to deliver painless tingling sensations to its patients, while adjustable duration pulses help decrease muscle spasms and increase local blood flow to injured areas. This frequency can also help decrease spasms.
Studies have revealed that high frequency TENS may help alleviate chronic neuropathic pain, as its effect is mediated by opioid receptor antagonists which prevent proinflammatory cytokines and neurotransmitters that increase central excitability from increasing central excitability. Furthermore, it appears to reduce microglial activation and glutamate release in the spinal cord; its benefits could even be enhanced through taking acetaminophen.
Evidence to support TENS as an effective treatment of musculoskeletal conditions is currently scarce, though two randomised controlled trials involving patients suffering from rotator cuff impingement or adhesive capsulitis produced mixed results; however, due to low quality evidence and heterogeneity within comparison groups resulting from these RCTs it cannot be drawn upon with certainty; future RCTs must implement well-designed methods when evaluating conventional TENS treatments in relation to treating these disorders.
TENS is a noninvasive modality used to treat musculoskeletal conditions like fibromyalgia. When combined with other therapies such as massage or exercise, TENS may offer further relief. Patients should be educated about its potential side effects such as minor redness at electrode placement that will subside quickly. Furthermore, repeated use at similar intensities and frequencies can cause analgesic tolerance and thus diminish its effectiveness.
TENS provides rapid and short-lived analgesia; however, its effect can be prolonged by changing frequency or intensity settings. TENS should never be used on areas of infection or broken skin and any discomfort should be reported immediately to their therapist; additionally they may experience sensations similar to clawing or grabbing by electrodes – this is common and should be reported accordingly.
TENS can assist those living with fibromyalgia by increasing endogenous opioid sensitivity, inhibiting proinflammatory cytokines and neurotransmitters, increasing blood circulation to injury sites, and modulating pain modulation. Furthermore, TENS may help alleviate musculoskeletal problems while improving sleep patterns.
Mixed frequency
TENS, or transcutaneous electrical nerve stimulation, uses portable stimulators that produce electric currents to excite or depress neurons in order to provide pain relief as well as treating conditions like fibromyalgia, muscle tightness and arthritis. It has also become an integral component of therapy protocols in other disciplines.
Tense muscles can cause chronic discomfort in the back, shoulders and neck area. TENS units offer relief by offering multiple frequency settings, pulse width options and intensity settings; using TENS regularly has proven its lasting effectiveness.
TENS units offer an effective combination of low, medium and high frequencies to deliver treatment with greater efficiency. Furthermore, TENS units allow users to set desired intensity levels as well as choose between audible or inaudible signals for maximum convenience.
Most TENS devices are battery-operated and allow the user to select frequency, pulse width, and intensity levels. Many systems include up to 10 channels for simultaneous therapy of multiple areas simultaneously. Electrodes typically connect the device to skin that can be adjusted into position for use.
Research has proven the efficacy of TENS; however, when used with patients it should be carefully considered due to various factors including type of pain being treated, duration and intensity of TENS treatment as well as potential adverse reactions, patient safety and efficacy issues and interactions with long-term opioid usage.
TENS has been proven effective at relieving neuropathic pain by inhibiting afferent input to the central nervous system, but it remains unclear which TENS frequency and electrode positioning are optimal for relieving such pain. TENS can be delivered either with high frequency (80-110Hz) or low frequency (2-10Hz), with either option potentially having an impactful pain relieving effect; additionally it could be applied over skin located ipsilateral to or contralateral to an injury, though its impact remains uncertain.
