Pain signals are transmitted along nerves. Medications that treat pain find ways to chemically interact with the nervous system to stop pain signals from reaching the brain. However, electrical impulses in the nervous system are also key to transmitting pain signals. Therefore, electrical stimulation therapy is also able to interfere with and stop pain signals from being transmitted.
How electrical stimulation works
When pain is experienced in the body, such as in the foot, the nerves carry pain signals from the foot up to the spinal cord. From there, the pain signals are transmitted to the brain. Electrical stimulation therapy works by interrupting this pattern of transmission, usually at the spinal cord. Some stimulation therapy devices involve the placement of electrodes on the skin, while others involve the surgical placement of electrodes under the skin next to or, inside in some cases, in the spinal column.
Because all pain signals must travel through the nerves, regardless of origin, stimulation therapy can provide relief from many different pain conditions. Some of these conditions include:
- Failed back surgery syndrome
- Degenerative disc disease
- Phantom limb pain
- Diabetic peripheral neuropathy
- Post-herpetic neuralgia
Pain conditions that are specifically nerve-related, such as diabetic peripheral neuropathy or phantom limb pain, may respond especially well to stimulation therapy.
However, stimulation therapy isn’t a good choice for everyone. In general, electrical stimulation therapy is a low-risk way to manage pain. It carries none of the risks that often accompany pain management medications, like nausea, constipation, addiction, or interactions with other medications. In fact, some studies have shown that using stimulation therapy can reduce the amount of medication that pain patients require.
Despite this, stimulation therapy is the use of electricity. For this reason, anyone who already has an implanted electrical device, such as a pacemaker, should have a conversation with a physician before considering stimulation therapy.
Additionally, most forms of electrical stimulation therapy are either unsafe or untested for pregnant women and children under 18 years of age. Anyone in these categories should also talk with a physician before considering stimulation therapy.
Transcutaneous electrical nerve stimulation
Transcutaneous electrical nerve stimulation (TENS) therapy is one of the most widely-used forms of stimulation therapy.
TENS therapy is popular for several reasons, one of which is its ease of use. The TENS device consists of a battery pack connected to electrodes. The electrodes are attached to the skin. Small electrical charges are delivered through the electrodes, which interrupt pain signals. TENS therapy can be used at home or the office very easily, although overuse of TENS can cause skin irritation.
Precise placement of the TENS electrodes can vary, depending on what type of pain is being experienced (local vs. widespread). Because the electrodes are easy to relocate, people using TENS therapy are able to experiment to find the most effective placement. Additionally, most TENS units are easy to adjust with a variety of settings, making them simple to customize for each individual’s comfort.
TENS units are available for purchase at medical supply stores. However, despite the easy access to TENS units, they are still medical devices. It’s still a good idea to discuss TENS therapy with a physician before trying it out.
Spinal cord stimulation
For serious, chronic pain, patients can ask a physician about an implanted spinal cord stimulation device.
Spinal cord stimulation essentially works the same way as a TENS unit. However, instead of electrodes on the skin, a spinal cord stimulation device has an electrode implanted inside the spinal column. This means that instead of blocking pain signals at the source of the pain, as in TENS therapy, spinal cord stimulation interrupts the pain signals in the spinal cord before they can reach the brain.
Spinal cord stimulation is more invasive than TENS, even requiring a surgery to place the device. Because of this, it’s usually not the first line of defense against chronic pain. Medications, nerve block injections, physical therapy, TENS, and other pain management techniques are usually attempted first. If these prove unsuccessful, however, spinal cord stimulation can be a good choice.
Before placement of a permanent spinal cord stimulation device, a trial device will be used for anywhere from a several days to a couple weeks. This will allow both patient and physician to assess how effectively a permanent device will control pain. Also, because this type of device is more invasive, it carries slightly higher risks, such as sensory or motor abnormalities. The trial period will show any abnormalities that might occur if a permanent spinal cord stimulation device is placed.
If the trail period goes well, it’s likely that the more permanent device will work well, too. These devices are often very successful, even reducing the number of pain medications needed. Typically, the implanted electrode is controlled by the patient, so he or she can adjust it based on pain levels. His or her physician will help find the right settings and learn how to safely adjust the device in future.
Spinal cord stimulation can potentially offer significant pain relief, but it also has several risks. There may be complications associated with leakage or failure of the battery. The electrodes can migrate away from the correct location. Allergic reactions, breakdown of skin, or loss of blood can occur at the implantation site. Fluid from the spine may leak, which can cause headaches. In rare cases, pain may be magnified instead of reduced.
New stimulation therapies
A device set to be released in 2015 may provide another means of at-home pain relief from stimulation therapy.
The Quell device, which is made by NeuroMetrix, is a wearable nerve stimulation device. Like the fitness bands that are all the rage, the Quell is strapped onto the upper calf and worn all the time. However, unlike TENS or spinal cord stimulation, the Quell doesn’t use electrical impulses to interrupt pain signals. Instead, according to Engadget:
“Quell stimulates the sensory nerves in your calf, then sends neural pulses to your brain, where they trigger the body’s natural pain relief response releasing endogenous opioids. Finally, these opioids send pain signals toward the delta opioid receptor, which is what triggers those tedious feelings, and reduces the amount of pain you’re experiencing.”
Even though it works a little differently than the established stimulation therapy, Quell has some serious benefits. When released, it will be available without a prescription. It’s as easy to wear and carry around as any other wearable device. According to its method of function, it should provide full-body pain relief. It also senses and adjusts for nighttime, so that it can provide pain relief without disrupting sleep. Better sleep can in turn reduce pain and make it easier to keep active, which can further reduce pain.
Additionally, like other forms of stimulation therapy, Quell can reduce the amount of pain medication needed. The only potential side effect listed on the Quell’s website is mild skin irritation if it’s used for too long a period. While it’s still a good idea to check with a physician before starting any sort of stimulation therapy, Quell already has FDA approval, which should go a long way toward smoothing any concerns.
Have you ever used electrical stimulation therapy?
Image by JD Hancock via Flickr