How to Compare TENS Units – A Review of Price & Performance
Once you’ve decided to consider TENS (transcutaneous electrical nerve stimulation) as a treatment option, you’ll want to know something about how much it will cost. Not surprisingly, there’s a wide range of prices for TENS units, and those are influenced by the performance – that is, the sophistication of a device’s features and the variety of programs it offers. Prices range from under $100 to several thousand dollars, but picking the right device doesn’t have to be challenging with a bit of guidance about how to compare units.
Reader note: This article is the third in a series that explores how to compare TENS devices. Other posts discuss how to evaluate TENS units by signal type or therapeutic function. Also see the end of this article for a quick reference guide on prices and features.
TENS Units – One Name, Many Different Devices
Before diving into an analysis, it’s important to clear up a common misperception – that all TENS devices are the same. This is like saying one pill is just like any other. Categorically, these devices are used to treat chronic and acute pain, and, in some cases, muscle conditions.
The one attribute all transcutaneous devices do have in common is that they transmit electrical signals through the skin by way of electrode pads that adhere on top of the treatment area. The challenge – the confusion, really – is that the category itself and a specific device type within the category both get referred to as TENS.
It’s a bit like facial tissue being called Kleenex®. There is a specific brand named Kleenex® within the facial tissue category, but many people have gotten used to calling all facial tissues “Kleenex.” In this article, any mention of TENS will be referring to the TENS category unless stated otherwise.
Evaluating TENS Units by Price & Performance
When evaluating the merits of various TENS devices, price is important but isn’t the be-all and end-all. Comparing price in combination with performance features like signal frequency and complexity, as well as the availability of pre-defined treatment programs, though, can provide a basis for gauging a device’s likely effectiveness in treating a patient’s condition.
Signal Frequency – High vs Low
Signal frequency is a key factor, but it’s not just as simple as higher is better. What’s important to understand is that different frequencies have the ability to affect nerves and muscles in specific ways.
In the case of low-frequency TENS units, these devices deliver a signal of generally 50-150 Hz to a small area of the body, targeting subcutaneous nerves in an effort to interrupt pain signals via the Gate Control Theory. Due to skin’s natural resistance, however, low-frequency signals can only penetrate so deep into tissue. Hence, they tend to provide pain relief only while worn. In fact, some low-frequency units are recommended to be worn continuously for patients to experience relief.
An example of a low-frequency TENS device is the Omron® Max Power Relief®, which lists for $70. Powered by two AAA batteries, it offers nine pre-set modes that deliver up to a 238 Hz frequency signal. There is also the Ultima 5, which lists for around $40. It operates on two AA batteries and offers five pre-set modes that deliver up to a 150 Hz frequency signal.
In contrast, devices with higher-frequency signals are better able to overcome skin’s natural resistance to reach nerves deep within the tissue. In this way, they’re theoretically more capable of offering longer-lasting pain relief via the release of endogenous opiates in the brain, which can provide pain relief for hours after the treatment session.
The BioWaveGO™, which lists for $299, is an example of a higher-frequency TENS units. Powered by a rechargeable battery, it offers on-off functionality with different intensity settings to deliver up to a 3600 Hz frequency signal.
As with all TENS units, electrodes need to be replaced as they wear out. These costs generally range from $10-30 per pack, and packs last up to 30 days when used daily.
Signal Complexity for Pain Relief
A common option from more sophisticated TENS devices is having the ability to apply two slightly different high-frequency signals that overlap in the treatment area. Called Interferential (INF) therapy, this treatment creates a “sweet spot” where the therapeutic benefit should be greatest. (Image A)
One of the devices that offers this type of therapy is Pro-Med Specialties’ BLD Stim3, which lists for $730. Powered by four AA batteries, it features the ability to lock-in a single pre-programmed session that delivers overlapping signals of 4000 and 4400 Hz. There is also the BioWaveHOME® that lists for $1,050. Powered by a rechargeable battery, it features a single pre-programmed session that delivers two overlapped signals of 3800 and 4000 Hz.
Even more advanced units can offer pre-modulated INF therapy, which differs from regular INF in that the current for each channel is mixed within the device – before being delivered to the body. (Image B) When the signals are pre-modulated, the area of interference stretches between each set of electrodes – not just where the signals intersect. The result is that pre-modulated INF often provides a significantly broader area of pain relief, allowing for the treatment of larger body areas more readily than most other TENS devices.
One device that offers pre-modulated INF is RS Medical’s RS-4i® Plus, which lists for $1,250 and is powered by a rechargeable battery. Among its pre-defined treatment programs are sessions that incorporate high-frequency 4900 and 5000 Hz pre-modulated INF signals for pain relief.
Signal Complexity for Muscle Stimulation
Another therapy offered by some TENS devices is Neuromuscular Electrical Stimulation (NMES), which uses alternating low-frequency signals (less than 100 Hz) to produce muscle contractions in the area being treated.
Muscle stimulation is thought to help restore normal muscle function, particularly in cases where patients suffer from muscle spasms or disuse atrophy. During muscle therapy, low-frequency signals penetrate the dermal layer and target the nerves within muscle tissue – the same nerves used to cause the muscle to function. That causes muscle fibers to shorten, so muscles contract and relax repeatedly, pushing out metabolic waste and pumping in fresh fluids during the process.
Few devices are NMES only, however, there is the Compex Wireless’ Muscle Stimulator Kit. Listing for $600 and powered by a rechargeable battery, it features nine pre-programmed NMES sessions that deliver a low-frequency 95 Hz signal.
Other devices, including the H-Wave H4, offer multiple treatment options. Listing for $3,300 and powered by a rechargeable battery, the H4 offers two modes – low-frequency muscle stimulation treatments and high-frequency pain sessions in the same unit at a maximum of 70 Hz.
For a device that offers both treatments together in a single programmed session, look to RS Medical’s RS-4i Plus. The RS-4i Plus is the only device that delivers both treatment modes concurrently. In a program known as Intersperse®, the RS-4i Plus runs a 35-minute session of high-frequency pre-modulated INF treatment during the relax phase of a low-frequency 71 Hz NMES treatment. The benefit of this is that patients can receive both pain relief and muscle therapy in the same session.
An added dynamic to consider when comparing TENS devices is the availability of pre-programmed therapy sessions. Some devices offer only one or two settings (i.e, simple on-off function or a few modes), while others offer multiple programs that are specific to treatment areas or treatment types.
Being able to compare price against the simplicity or specificity of such programs is helpful when gauging whether it’s a good value for the patient. A device that offers only pain relief or only muscle stimulation may be enough for certain cases, while other cases may demand both – or both in a single treatment session.
A device that is simplistic from a programming perspective is the BioWaveGO, where the only setting is intensity level. Alternately, some devices – like the Ultima 5 and Omron Max Power Relief – expand the options with five or nine pre-programmed sessions specifically for treatment areas such as the back, legs or shoulders, or for modes like constant and burst.
One device that offers top-tier sophistication from a programming perspective is the RS-4i Plus. Its suite of pre-programed sessions are divided into sub-groups that deliver:
Pre-modulated INF only sessions
NMES only sessions
Intersperse (delivers both at the same time)
Sequential stimulation (combines both in two- and three-segment treatments where one treatment mode follows the other)
To keep usage simple, a healthcare provider sets the program group on the RS-4i Plus. Each program group includes the 5-10 sessions that best meet the patient’s needs. For any healthcare professional who wants to define the parameters of their own programs for individual patient conditions, those options are available too.
A last consideration for comparing TENS units is looking at the type of battery the device uses. While this is not the most important single feature, it can be an ease-of-use consideration (or an annoyance factor) for a device in question – impacting overall cost of ownership and creating additional waste.
As noted above, many low-frequency devices use AA or AAA batteries, while most high-frequency devices feature rechargeable batteries – since higher power and greater sophistication generally require a greater charge. This can play into the overall cost of operating any device, as replacing batteries on a weekly or semi-weekly basis – on top of replacing electrodes on a monthly basis – may be burdensome for patients.
Knowing that all transcutaneous electrotherapy devices are not the same is the first step in understanding the TENS category. Taking a deeper dive into what makes them different reveals that there are varying prices and performance distinctions between devices. These may be used to determine which device is best for addressing a patient’s particular condition.
Some questions to consider when reviewing different devices:
What are the desired treatments? If a device is indicated only for pain, it isn’t a good choice for muscle treatment. If muscle therapy is the goal, make sure the device is indicated to relax muscle spasms, prevent disuse atrophy and/or re-educate muscle.
How deep is the pain? For deep muscle pain, a device that offers pre-modulated INF can provide greater benefit than a unit that doesn’t. If targeting superficial pain, then a unit offering only low-frequency signals may suffice.
Does the device need to offer flexible modes or different programs to meet the patient’s needs? If so, those with only a single program or a single mode will likely not suffice.
Will a unit that takes AA or AAA batteries prove costly or cumbersome to operate? If so, then considering a device with a rechargeable battery could make more sense for the patient.
Do you have experience with TENS electrotherapy devices? If so, feel free to add your questions or comments.
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