Is Electrical Stimulation Safe?
Whether electrical stimulation is safe or not, is a question we are sometimes asked. In this article, we glimpse the many applications of electrical stimulation and we take a look at the issue of safety.
Electrical stimulation therapy has become an increasingly popular method used in rehabilitation, physical therapy and occupational therapy for muscle strengthening. pain relief and much more. This alone suggests it is likely to be relatively safe and effective but let's take a closer look. Here is our video introduction.
Why do we use electrical stimulation?
At Anatomical Concepts, we are enthusiastic about electrical stimulation and we offer this technology in different forms to support a wide variety of applications for our clients including:-
FES Cycling is an valuable application of electrical stimulation.
FES Cycling - allowing persons with weak or paralysed muscles to cycle for exercise using their muscles actively. Electrical stimulation is synchronised with the movement of the bike pedals.
Exercising and strengthening muscles by using electrical stimulation to support functional movement. This can be used to assist recovery after a stroke, spinal cord injury or other neurological condition and can support many applications with the arms, legs or trunk.
Relaxing spastic muscles is possible by stimulating the antagonist to a tight muscle or, by careful choice of stimulation settings directly applying stimulation to the affected muscle.
Restore muscle tissue health and size following various types of nerve injury. When nerves are injured they cannot be used to trigger muscle contractions but certain electrical stimulation units and electrodes are specially designed to make muscle fibres contract directly
Wound healing with chronic pressure ulcers. This can be a very effective modality with pressure ulcers although the physiological mechanisms that lead to tissue repair are not completely understood.
It seems amazing that so many things can be achieved with electrical stimulation but we should recognise that this concept is not “one thing” for one type of application. Each application will need stimulation settings and equipment selected especially for that purpose. It's easy to imagine, for example, that we will need different approaches to strengthen a muscle compared to relaxing it. Even with one type of application, it can be best to adjust such a system specifically for an individual case. This takes some experience and specialist knowledge to do well.
Just like any technology we deal with, we approach this area by always considering whether, for a particular individual, this technology will be safe and effective (in addressing a clinical need). We should recognise that there will be some general risk factors and then specific contraindications we should check for with each individual.
Applying stimulation energy
Fundamentally, electrical stimulation is applying a form of energy to the body for a particular physiological and then therapeutic effect. If you think about it, we can also use other forms of energy to produce a physiological effect; including heat, cold, vibration/ultrasound. Each of these may have benefits in particular situations but in this article, we will restrict discussion to electrical energy which is typically easy to modulate and control.
Imagine that we have something that generates electrical energy in a controllable manner - a stimulator. We then need a means to apply that energy to the tissues we are working with - this is done with "electrodes".
The nature of the energy needs to be controlled so that we get the physiological effects which hopefully lead to the therapy effects that we want without any unwanted risks.
Electrical stimulation in rehabilitation is usually applied via electrodes placed on the skin surface over the part of the body of interest, although there are other applications in medicine where electrical stimulators are implanted in the body.
electrical stimulation using surface electrodes
There are usually going to be two electrodes. Simplistically, we could think of one as being the point of entry of the energy into the body and the other electrode as being the path out. In other words, we have a flow of energy transcutaneously (through the skin) and potentially influencing the sensory and motor nerves. The skin surface tends to resist the flow of energy and so electrode designs typically use a gel or water to reduce this resistance and make it easier for the energy to penetrate the skin.
By fine-tuning the stimulator we might be able to bring about all the effects we discussed above. Over many decades, practitioners have learned how to control stimulation to get the effects we need. In other articles, we have looked at the patterns of energy often used for different effects.
Many times we are influencing the nerves but in some special cases, we target other tissues. For example, with wound healing we may be encouraging blood flow to any area and with nerve injuries we may be encouraging muscle fibres to contract directly rather than relying on the nerve structures.
Types of electrical stimulation
One of the things that confuse observers and consumers in this field is the lack of an agreed terminology to describe the many forms of electrical stimulation. For example, we might see TENS (Transcutaneous electrical nerve stimulation) used and recognise this as associated with the means of stimulating sensory nerves for pain relief. However, we could also classify electrical stimulation that makes muscles contract as transcutaneous as it must create its effects by passing through the skin and deeper tissues to affect a nerve.
We will most commonly see terms such as neuromuscular electrical stimulation (NMES) or functional electrical stimulation (FES) used in rehabilitation applications where the goal of treatment is usually to generate a strong muscle contraction by stimulating the motor nerve of an innervated muscle.
Ensuring safety
electrical stimulation can be used to support simple and complex applications
Safety is of course a paramount concern when considering any medical intervention. When it comes to electrical stimulation therapy, certain precautions need to be taken to ensure its safe and effective use.
Firstly, it is crucial to obtain patient information. This includes assessing the patient's medical history, any existing conditions, allergies and medication use. Close monitoring and frequent assessment of the patient's progress and response to electrical stimulation therapy are essential to ensure safety and effectiveness.
Secondly, an objective is needed. What is the purpose of using electrical stimulation? As we have seen, there are many potential applications and we need to choose the right stimulator and electrodes for the situation.
Third, check the equipment is of appropriate design and certified for use. A quick web search will show numerous stimulator variations with vastly different costs. Some will be battery-powered and some mains powered. It is particularly important with mains-powered equipment that the equipment used is a product certified for the intended application. A certified medical device will have had exhaustive safety testing but many devices created for sports applications will not strictly speaking be certified for medical applications. Remember that not all devices will be suitable for all applications.
Fourth, check for contraindications. Any electrical stimulation product and technique will have some contraindications that may impact its use. The product manual should spell these out in detail. These individual contraindications might be described as absolute or relative risks. We would recognise absolute contraindications as being a firm recommendation that electrical stimulation should not be used whilst general contraindications could be considered as representing a greater degree of choice.
Sometimes we have to weigh up the benefit of applying electrical stimulation against the risks. Therefore in some situations, it might be reasonable to proceed with the application of stimulation even though some relative risks are present.
Typical contraindications
Certain contraindications are commonly seen, but as stated above, the individual product manual should always be consulted because of the vast range of potential applications. If a manufacturer states a contraindication is absolute, this advice should be followed
Pregnancy - we don't know if there might be a risk to the fetus. In some situations, a clinician may believe it appropriate to proceed with electrical stimulation if the perceived benefits are high enough.
Wounds or scars in the electrode area. Damaged skin should be avoided when applying electrodes. The skin needs to be intact, clean, and dry to prevent any adverse reactions or infections. Patients should be educated on proper electrode types, size, placement, maintenance, and usage. Instructions on how to use the electrical stimulation device should be provided to maximize safety and efficacy.
Metal implants might represent a contraindication depending on the application.
Active implants might represent a contraindication depending on the application, situation of the implant and it's design
Skin diseases in the area should be investigated before the application of stimulation. Allergies can arise in a few individuals and stimulation should be discontinued until the cause is clear. In some cases, a different type of electrode can be used.
Conclusion
When used appropriately and according to individual patient needs, electrical stimulation therapy can be a safe and effective treatment option. However, it is essential to respect the limitations and precautions associated with this therapy. Adherence to proper protocols and guidelines, proper patient education, and professional supervision are crucial to ensure positive outcomes and minimize potential risks.
In conclusion, electrical stimulation therapy has proven to be a valuable tool in physical therapy for pain relief and muscle strengthening. Through the use of devices such as TENS units and EMS devices, electrical stimulation therapy can provide fast pain relief and improve overall function. However, safety should always be a top priority when administering electrical stimulation therapy. By following proper protocols, educating patients, and working under the guidance of healthcare professionals, electrical stimulation therapy can be safely and effectively used to manage chronic pain and enhance rehabilitation outcomes.
Related articles
https://www.anatomicalconcepts.com/articles/why-is-electrical-stimulation-used-in-rehabilitation
https://www.anatomicalconcepts.com/articles/can-electrical-stimulation-treat-chronic-wounds
https://www.anatomicalconcepts.com/articles/5-benefits-of-using-fes-bikes-for-rehabilitation-and-fitness
https://www.anatomicalconcepts.com/articles/what-is-the-purpose-of-functional-electrical-stimulation
https://www.anatomicalconcepts.com/articles/what-is-the-success-rate-of-electrical-stimulation-for-pain
https://www.anatomicalconcepts.com/articles/fes-and-peripheral-nerve-injuries