What is the success rate of electrical stimulation for pain?
Electrical stimulation is a commonly used treatment for various conditions, including pain relief and can often be very effective. What would count as success very much depends on the reason for the pain and it’s severity. In some cases, pain relief with any technique will be temporary but then the benefit may have to be weighed against other factors. As with any potential treatments there are contraindications and indications.
We would typically need to consider electrical stimulation effectiveness and safety in comparison with possible alternatives. As electrical stimulation is relatively safe and non-invasive in many situations it is often worth trying before more invasive alternatives are considered for example.
What is not so often understood is that electrical stimulation for pain relief is not just one approach but a range of approaches that ideally are chosen based on the type and origin of the pain. Many clinicians and their patients have heard of TENS, (transcutaneous electrical nerve stimulation) but this is not the only protocol available. There is a basic issue with terminology because the vast majority of applications of FES are transcutaneous. When we are thinking of ‘TENS’ for pain relief we are actually thinking of a specific pattern of electrical energy that often has an analgesic effect.
We will describe what is behind the TENS approach as well as other approaches that might not be so well known. At Anatomical Concepts we deal with a product called the Stimulette Edition 5 which boasts a number of built-in protocols for the management of pain. In this article we will describe how electrotherapy can be used to work with pain and the specific abilities of the Edition 5.
Types of Pain
It might not be obvious that there are, in fact, different types of pain that we might see in a rehabilitation context.
Acute pain - in our context is closely associated with tissue damage which is likely to resolve relatively quickly
Chronic pain - is defined by it’s persistence for at least 3 months after healing is presumed to have occurred.
Acute Pain examples might include:
Post-operative pain: Electrical stimulation can help reduce pain and inflammation after surgical procedures and be used to promote healing.
Sports injuries: Sprains, strains, and muscle tears are common sports-related acute pain that may benefit.
Acute back pain: Sudden onset of back pain due to muscle strains or ligament sprains can potentially benefit.
Chronic Pain examples might include
Osteoarthritis: Chronic joint pain caused by the degeneration of joint cartilage and the underlying bone
Rheumatoid arthritis: This chronic autoimmune disorder causes inflammation and pain in the joints.
Fibromyalgia: This chronic pain disorder can cause widespread pain
Neuropathic pain: Pain caused by nerve damage, such as diabetic neuropathy, spinal cord injury, sciatica, or post-herpetic neuralgia.
Chronic back pain: Long-lasting back pain resulting from conditions like herniated discs, spinal stenosis, or spondylosis
As we will see, some forms of electrical stimulation are more suited to particulat types of pain
What is Electrical Stimulation?
We have known for many decades that we can use electrical energy to produce effects on muscle, nerve and tissue. In the management of pain this energy is used to stimulate nerves which can override or block pain signals and reduce the sensation of pain for the patient. While the success rate of electrical stimulation for pain can vary depending on the individual patient and their specific condition, many studies have shown positive results. Physical therapists and other healthcare professionals may use different types of electrical stimulation depending on the patient's needs and goals.
When using electrical stimulation for pain relief, electrodes are typically placed on the skin over the affected area and an electrical impulse or stimulation is delivered through the electrodes. The real issue to consider is the exact forms of electrical energy that can provide relief in the spectrum of applications.
Effective Waveforms
The Stimulette Edition 5 has seven different waveform protocols for pain. The obvious but difficult question then is how to choose which ones to use in a particular case?
To discuss the differences in protocols we are looking at the different stimulation parameters which are typically the waveform frequency, amplitude, mode of delivery and pulsewidth. In general terms, the following table summarises the effect of changing the stimulation parameters.
In all cases the ultimate choice and level of intensity should be guided by the patients comfort and absence of contraindications.
The following table summarises the waveform “families” available in the Edition 5. By monophasic waveforms we are referring to ones which are not balanced around zero intensity - they have a positive or negative “imbalance”. We mostly favour Biphasic waveforms for reasons we wont explore here.
A distinction is made in the table above between the various types of pain as a starting point. In addition we generally recommend using Biphasic waveforms as being generally more useful with individuals who are sensitive to stimulation - the GALV waveforms used for iontophoresis especially require an ability prescribe and require practical experience and should be avoided for home use.
Some waveforms are particularly favoured in some countries - ie DIAD in France, UR in Central Europe - but these are virtually unknown elsewhere. There is a lack of formal research information on how the various waveform options compare in terms of effectiveness and how the parameters should be chosen.
The fact is, some experimentation will almost certainly be needed to choose a waveform and associated parameters that work. The good news is that such experimentation involves little risk if approached with care.
Probably the best place to start in many cases is with the TENS waveforms utilising the Biphasic forms.
In actual fact, the Edition 5 offers three versions of the TENS waveforms - described as TENS-LFT - TENS-HFT - TENS-BuT
These three TENS waveforms are for Acute, Chronic nociceptive pain, Neuropathic Pain.
The waveforms TENS-LFT and TENS BuT in particular are our starting point for treating chronic pain
TENS HFT is used for acute pain
These waveforms are well tolerated and can be used by persons sensitive to stimulation. For central nervous pareses the acupuncture points can be used.
The manufacturer contrasts the low frequency character of TENS-LFT with the high frequency of the other waveforms as they get results by different means. The low frequency character of TENS-LFT generates the secretion of the body’s own pain-reducing hormones. The analgesic effect only increases slowly and a treatment duration of 30 minutes is recommended. Due to the low frequency the A delta fibres are stimulated - the opioid mechanism activated. The TENS-HFT creates a faster pain dulling effect.
TENS-BuT consists of pulses delivered in a “burst”. The suggestion is that burst mode TENS effectively stimulates both the pain gate and the opioid mechanisms simultaneously.
Dose/Application
The suggestion is that for joint pain and for radiating pain one electrode is placed in the spinal cord area where the nerve originates and the second electrode is placed in the distal painful area.
For TENS-LFT increase the intensity until a “tapping” sensation is felt. For high frequency versions TENS- HFT and TENS-BuT the sensation will be more like a vibration effect. Treatment duration 10 to 30 minutes typically.
Conclusion
Electrical stimulation is often used to treat pain, but its success depends on factors such as the type and severity of the pain. The good news is that electrical stimulation is relatively safe and non-invasive in many situations, so it can be tried before more invasive alternatives are considered.
Remember though that electrical stimulation is a general term and you need to identify the specific type of waveform that will be both safe and effective. This typically involves some patient testing of the alternatives whilst be being guided by the best person to judge the result -t he patient.
We have seen that different types of electrical stimulation can be used for different types of pain, such as acute and chronic conditions.
The Stimulette Edition 5 product boasts a number of built-in protocols for the management of pain, including various monophasic and biphasic waveforms.
Using this product, the TENS-LFT, TENS BuT and TENS HFT are three versions of TENS waveforms which we will often try first to reduce pain; their parameters must be chosen with care based on patient comfort levels.
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