Complex Regional Pain Syndrome (CRPS) also known as reflex sympathetic dystrophy (RSD), causalgia, and a host of other names is kind of like headaches and neuropathy were for me. In that I didn’t initially have any particular interest in the condition but I have a tremendous interests in electric stimulation, particularly electrical muscle stimulation (EMS) and its application to various diagnosis. And my results with using EMS and TENS currents with both headaches and neuropathy have been fantastic and I think the lessons I learned in my “year of EMS” self experiment about various machines, parameters, and electrodes leads me to think I can improve upon what’s already been shown to be positive outcomes in a number of studies. Reading those studies, it gives me some ideas to try with my patients in what I hope is a positive spinning cycle that can reverse the negative spin of chronic pain. So what I intend to do with this review, is link and list comments from relevant papers I was able to acquire, and comment on how I might synthesize that knowledge together for an optimum outcome of maximum recovery, in minimal time, expense and discomfort.
It also happens that CRPS is tremendously difficult to treat, but seems as though it should get better without drugs or surgery if we can just figure out what may be more than one factor to help it get better. Since learning how to successfully treat other multifactorial problems, like chronic back pain and tendinopathy, I have this confidence (hopefully not false) that I can do the same with other conditions, and on paper CRSP seems like the perfect candidate, where you want to decrease pain, restore blood flow, and eventually restore strength and function and do so in a way that’s going to keep you from freaking out. I’ve had a file on electric stimulation and CRPS and it just had papers from the 70s and early 80s in it with no recent follow up. In rehab it seems electric stimulation was forgotten for a few decades all while the technology became better, machines became a LOT less expensive. While all the TENS and EMS research has been going on, with CRPS most of the papers coming out have been with the use of surgically implanted spinal cord stimulators. While that research has been positive it sounds hella invasive, and I really do think that if you really know what you are doing with electrical stimulation (to leverage up all the variables of TENS and EMS) I think it should work better better than the surgery at a fraction of the cost. So I’m going to start writing about how I would leverage those variables, what researchers from each study figured out that was or wasn’t followed, and what I think they all missed that might help.
I’ll start off with a paper I just read, a new 2016 study that confirmed in a double blind study that TENS, when added to a physical therapy program substantially improved outcomes, and was the impetus for this blog.
The effectiveness of transcutaneous electrical nerve stimulation in the management of patients with complex regional pain syndrome: A randomized, double-blinded, placebo-controlled prospective study. Bilgili A, Çakır T, Doğan ŞK, Erçalık T, Filiz MB, Toraman F. J Back Musculoskelet Rehabil. 2016 Nov 21;29(4):661-671.
MATERIAL AND METHOD:
The study included 30 patients with stage 1 and 2 CRPS Type I in the upper extremities. The patients were randomly assigned into 2 groups, group 1 (n= 15) received conventional TENS therapy for 20 minutes, and group 2 (n= 15) received sham TENS therapy. The standard physical therapy program, which included contrast bath for 20 minutes; whirlpool bath for 15 minutes; assisted active and passive range of motion, and static stretching exercises up to the pain threshold, was also conducted in both groups. Therapy was scheduled for 15 sessions. A visual analogue scale (VAS) was used to assess spontaneous pain. The Leeds Assessment of Neuropathic Signs and Symptoms (LANSS) scale and the Douleur Neuropathique en 4 Questions (DN-4) were used to assess neuropathic pain. In addition, range of motion (ROM) was measured using a goniometer and volumetric measurements were taken to assess edema. Functional capacity was assessed using a hand dynamometer and the Duruöz Hand Index (DHI). All measurements were performed at baseline and after therapy.
Significant improvements were achieved in spontaneous and neuropathic pain scores, edema, ROM, and functional capacity in both groups (p< 0.05). However, improvement was found to be significantly greater in group 1 regarding pain intensity, neuropathic pain assessed using LANNS, edema, and in the 2nd-3rd finger ROM measurements (p< 0.05). No significant difference was detected between groups regarding improvements in 4th-5th finger and wrist ROM measurements, grip strength, and DN4 and DHI scores (p> 0.05).
The addition of TENS to the physical therapy program was seen to make a significant contribution to clinical recovery in CRPS Type 1.
This paper cost me 27 Euros! The abstract says the TENS worked, but the absolute results indicate the TENS worked better in almost all the parameters tested, just failing to achieve statistical significance in some, and often that improvement was several fold better than the rest of the therapy combined. The physical therapy program included 15 sessions (sessions per week not given) including:
- real or sham TENS for 20 minutes, if real “Conventional TENS” with a Chattanooga Mobile Stim 2777, 100 hz, 50-100 uS, “amplitude that did not cause discomfort” with two 6×8 cm carbon electrodes with one place on the dorsal forearm and dorsal hand.
- hot whirlpool bath for 15 min
- hot and cold contrast baths 20 min
- exercise (daily active, active assistive, and passive ROM of wrist and finger joints 3 sets of 10 reps each)
- up to 4 grams paracetamol per day
Pain decreased 70% in the TENS group compared to 34% in the placebo group. Edema (swelling) in the hand decreased 12.33 mL with TENS more than four times better than the 3.0 reduction with SHAM and all the rest of the physical therapy. Range of motion of every finger digit was better with TENS from 70 to 133% over sham, though for some reason wrist ROM trailed slightly (16 to 43%). Grip strength improved 6.87 kg in the TENS group, more than double the 3.4 kg improvement in the sham group.
Overall I think this is a great paper. I would have liked to know over how many the weeks the 15 treatments were spread and how high of mA the patients worked up to over that time period and if higher electric stimulation intensities were related to greater outcomes. Also I was glad to see they used rubber carbon electrodes instead of the sticky versions as rubber carbon allows for greater stimulation with less pain, which I expect would be extra important in the RSD patient group. It sounds like with the varied pulse width of 50 to 100 uS they were using amplitude modulation of the TENS, which I expect helped over just a flat constant pulse width TENS, though I prefer frequency modulation, where the rate (Hz) is varied over time rather than varying the pulse with.
My thoughts on improving outcomes further would be to extend the TENS treatment time to at least 30 minutes as I recently read a paper that found pain sensitivity decreases more at 30 minutes than at 10 or 20 minutes in normal subjects at least. Also I would wonder (as was noted in some older research) if doing the TENS three or even four times per day would work better than once a day, or once three times per week. I would expect more to be better, which is often the case with electric stimulation and pain reduction. Also it seems they were using the TENS specifically to reduce pain in hopes that the exercise program would improve function. I would think that as the patient’s tolerance to the electrical currents improves they could start adding in EMS currents (with a wider pulse width of 300-450 uS) keeping the on period frequency high (100-120 hz) with a 5 second on, 15 second off, or a 10 second on, 50 second off period. During the “off” period a 5 hz pulse could be programmed in (if using a Globus Genesy machine) which I expect would substantially improve blood flow to the affected extremity. Conversely, if using a budget machine, EMS at 5-15-10 or 10-50-10 could be to improve muscle strength, followed by a wide pulse width 5 hz “aerobic EMS” program for 20 or 30 minutes. All of the above “optimization” ideas run into practical, or at least financial, problems in the office where insurance usually reimburses for electrical stimulation for only 15 minutes of electrical stimulation per day. However on the very bright side, top of the line electric stimulators like the Globus Genesy can be owned for $500, and inexpensive two channel stimulators like the TwinStim4 work great for as $69. I’d think you’d still want to pair either with rubber carbon electrodes and good straps to hold them into place. Though the above study used rubber carbon electrodes, I expect larger ones (my favorite universal size is ~10 cm circular) would work better still. Also I would think that adding a second channel applied to the opposite (anterior or palmar) aspect of the hand and forearm would help. I would expect for CRPS in particular that larger electrodes and more channels for a longer time period, more often per day would be especially good, as it would allow more stimulation over a greater area with lesser discomfort, and combined with longer more frequent treatments would allow the person to decrease pain faster, so as to work up to higher TENS intensities, to where they could then make one of the daily sessions an EMS session to better improve muscle strength, endurance and circulation.
After the above 2016 study I have to go back to 1988 to find another paper describing the use of TENS on humans with CRPS.
During the past 6 years, ten children with reflex sympathetic dystrophy were treated. Pain in an extremity was the initial complaint in all patients. The pain was unilateral in 90% of the patients; upper and lower extremities were affected with equal frequency. Tenderness to palpation, extreme hyperesthesia, and dysesthesia were other dominant features. All patients had some evidence of autonomic nervous system dysfunction in the affected extremity (swelling, color change, decreased temperature, and/or hyperhidrosis). The median duration of symptoms prior to referral and diagnosis was 5 months. All children were treated as outpatients with a transcutaneous electric nerve stimulator and home-based physical therapy. With this regimen, seven patients had complete remission within 2 months. Two other patients improved with transcutaneous electric nerve stimulation therapy, and one patient had no response to transcutaneous electric nerve stimulation. Reflex sympathetic dystrophy is frequently underdiagnosed in children. Increased awareness of this syndrome is important because accurate diagnosis is crucial and transcutaneous electric nerve stimulation offers a safe, simple, and effective outpatient therapy for reflex sympathetic dystrophy in children.
“The initial treatment for our patients after our evaluation was the use of trancutaneous electric nerve stimulator for one hour four times daily. The pateints were instructed to place the electrodes over the vascular supply to the extremity and to adjust the voltage to the level of comfort. Physiotherapy was taught to the patients, and they were encouraged to exercise the affected extremity.”
“The signs and symptoms of reflex sympathetic dystrophy improved in nine of the ten patients. In fact, seven patients experienced complete remission within 2 months of treatment.”
“Following the introduction of the “gate control theory” of pain by Melzack and Wall, there was great interest in the use of electrical stimulation for the relief of pain. The Gate theory states that nonpainful stimulation of the peripheral nervous system can interfere with the relay of pain sensations in the CNS. This theory may explain why transcutaneous electric nerve stimulation appears to be effective in reducing pain.”
The results from above are amazing but seem credible to me. My only fault with the paper is that they didn’t describe the parameters (pulse width, rate, duty cycle, etc.) of the TENS used, however perhaps what parameters they used isn’t as important as the fact that they used those parameters four hours a day (60 minutes, four times). That’s 12 times as much as the above mentioned study, plus they were doing the TENS daily instead of a few times per week. That might be enough to explain why they are talking about how 7/10 were cured, instead of “significant improvements” over a control group.
That does seem one of the common themes as I read about TENS for pain control is that regardless of parameters used, TENS works in a dose response relationship, and four hours a day is a pretty good dose. I would caution that for that long of treatment, I’d think you would want to be using a reasonably light current. My 10-50-10 EMS or even 5 hz aerobic EMS would maybe only be best done once per day, though that still would depend on the intensity of muscle contractions given.
Also I thought their description of gate control theory was both concise and accurate, and I believe is the primary reason that TENS (and EMS too) work to decrease pain.
Beyond the above paper I had to go back to the 70s to find research on people.
“This is a report of a 3 ½-year-old boy with this syndrome successfully treated…”
“This previously healthy child suffered a right sciatic nerve injury following an intragluteal injection of an antibiotic.”
“The patient was begun on intermittent transcutaneous nerve stimulation… …set at 40 Hz, pulse width 80 microseconds, and voltage just below the point of discomfort. The proximal electrode was placed over the right femoral triangle and the distal electrode over the dorsum of the right foot. Stimulation was applied for 30 minutes, three times a day, for ten days by the physical therapist.”
“The patient was re-evaluated five days after starting treatment when a notable decrease in hyperalgesia and an increase in the ability to actively extend the right leg at the knee were noted.”
“Two days later the patient was free of all pain on both manipulation and palpation of the right leg and foot.”
“Four weeks following institution of stimulation, the patient was pain free and walking with a drop foot brace. Active plantar flexion of the toes indicated returning S1 function.”
If it were me, 30 minutes, three times a day, is probably where I would start. I’ve tried and sometimes use a similar electrode placement with an electrode over the femoral triangle, however I put the other on the bottom of the foot rather than the dorsum (top). I expect each would work but the sole of the foot being meatier should be more comfortable. In each case having the electrodes so far apart gives very deep stimulation, which I think would be ideal for CRPS. I would add that given that the child still had drop foot, four weeks later it would have been interesting to know what would have happened if EMS currents were applied to the tibialis anterior muscle after the ten days of TENS had eliminated pain.
Transcutaneous electrical stimulation was tested in 24 patients with chronic pain following a peripheral nerve injury in an extremity, in 10 patients with a good effect. All of these 10 patients displayed signs of increased sympathetic activity in addition to hyperalgesia. Sympathetic block gave complete freedom from pain. In 14 patients with the same symptomatology but without an increased or with only very slightly increased sympathetic activity, no or an insignificant effect was obtained. Sympathetic block did not relieve the pain in this group. Transcutaneous electrical stimulation should be tried as an alternative to sympathectomy in causalgia major or minor.
“Commercially available simulators were employed. The electrodes were placed over the nerve central to the lesion at the site where the stimulation caused paraesthesiae radiating into the painful area. As a rule the patients themselves arrived at the most suitable frequency and intensity of the stimulation.”
“In this series of patients with chronic pain after peripheral nerve injuries transcutaneous electrical stimulation was found to be of great value. The presence of increased sympathetic activity and complete elimination of pain by sympathetic block seems to be prerequisites for successful therapy with this method.”
Of the 24 patients they report 3 had “permanent freedom of pain”, 7 had “good/excellent effect”, and 14 had “no or transient effect.”
In this study the results seem good but not as great as noted above. Reasons for the differences are plenty. First they all had peripheral nerve injury which today would make them classify as CRPS (type II) which is less common and generally more severe than the type I variant, without obvious nerve injury. They also noted the patients had already “undergone repeated operations on peripheral nerves” indicating they were likely some of the toughest of cases, putting generally good results in some perspective.
Unfortunately these researcher didn’t give even basic information about the type of stimulation used, and while they say frequency and intensity were varied by the patient, they didn’t say how long or often the stimulation was applied. It sounds like the TENS was applied in single doses to see what would happen in combination with other treatments to include nerve blocks or surgical procedures. Interestingly they placed the electrodes proximal (above or closer to the body) to the nerve injury, which I think might be a good option if the site of injury and below is too sensitive to be touched, perhaps at least early on. Later I think there are advantages, including the delivery of more current with the electrodes placed both above and below (or on) the painful area. Also I wonder if could have been improved, particularly in the 7 who had “good/excellent effect” and the 14 with “no or transient effect” if the stimulation was provided longer or more frequent.
Case History Number 96: Reflex Sympathetic Dystrophy In a 6-Year-Old: Successful Treatment by Transcutaneous Nerve Stimulation. STILZ, R. J. MD; CARRON, H. MD; SANDERS, D. B. MD, Anesthesia & Analgesia: May/June 1977 – Volume 56 – Issue 3 – ppg 438-442
“This otherwise healthy child suffered a traction injury to her right sciatic nerve.”
“The condition persisted unchanged to the time of admission, 3 months after her initial injury.”
“Electrodes were arbitrarily placed over the right femoral triangle and the dorsum of the right foot. The frequency of stimulation was set at 90 Hz and the current at 2.5 ma, at which point a tingling but not painful sensation was noted by the patient. Later, these settings were changed to 50 Hz and 3.5 ma, which produced better pain relief.”
“Within 24 hours after initiation of the stimulation, definite improvement in color and reduced hyperesthesia [pain sensitivity] were noted…”
“The patient was then discharged from the hospital and was instructed to use the stimulator continuously at home; she was also strongly urged to bear weight on the foot.”
“There was little subjective change in symptoms over the next 3 days, but late on the 4th day, the patient began to experience significant relief of pain. On awakening on the 5th day following institution of stimulation, she was pain free and able to walk on the foot without discomfort.”
This is just a case study, but I find a lot of clinical wisdom in some of the older electric stimulation case studies. Again they used the femoral triangle/top of foot electrode placement. Stimulation frequency was reduced from 90 Hz to 50 Hz but I doubt that had much to do with the better pain relief. Rather I would think that due to the increase of current amplitude from 2.5 to 3.5 mA, which is still really low so I would guess they were using a machine with a wide pulse width (uS) though that information wasn’t given. But such low stimulation would explain why they were able to just turn the machine on, and leave it on. And perhaps the long duration of stimulation led to the remarkable short term recovery. The authors go quote Meyer and Field’s 1972 paper, but since I have that paper myself I’ll do it like I want right now.
“An accessible site, central to the point of injury was then selected for stimulation. The
stimulation parameters were 01 msec duration, unidirectional square pulses of variable voltage,
delivered at a rate 100 Hz. Electrodes consisted of insulated stiff copper wires, tipped with stainless steel balls of 3 mm diameter and 2 cm separation moistened with electrolyte paste and applied directly over the course of the nerve trunk being stimulated. If the electrodes were properly placed, paraesthesiae were elicited in the distribution of the nerve stimulated (Wall and Sweet, 1967). Although we did not monitor stimulus current, the voltage was adjusted so that no motor activity was produced and the sensation perceived was not reported as painful. This ensured that only larger diameter, more rapidly conducting fibres were activated (Collins et ah, 1960).”
“In order to produce satisfactory paraesthesiae it was necessary to stimulate a section of nerve proximal to the point of injury. Stimulation of affected nerves distal to the lesion usually exacerbated the pain, while stimulation of intact, near-by nerves was ineffectual. We were not able consistently to stimulate the sciatic or tibial nerve by the transcutaneous technique. In all cases, the upper extremity nerves were stimulated at the anterior axillary fold and the common peroneal was stimulated at the knee.”
“After paraesthesia; had been elicited in an area supplied by the nerve being stimulated for at least two but no more than three minutes, the stimulator was removed and the patients were asked if there had been any change in their condition.”
“If the electrodes were properly placed, the effect of stimulation was immediate dramatic relief of pain during stimulation for six of the eight cases. After stimulation, pain relief persisted for periods varying from five minutes to ten hours. Although the degree of pain relief varied from patient to patient, it was consistent for a given patient from trial to trial.”
“Two patients… …were able to begin physical therapy following their first trial of stimulation. Both patients were free of severe pain within one weak.”
“In general, the earlier treatment is instituted, the more likely it is to be successful.”
I think this is the 2nd oldest paper on TENS and causalgia, Wall and Sweet 1967 is cited by them as having performed the same procedures with similar results. There are all kinds of insights in this paper, such as making sure the nerve you stimulate is proximal (above) the area injured but that it must include the nerve that covers the affected area. That was a similar finding as what was talked about in the percutaneous (surgically implanted) electrodes for chronic migraine headaches and my own use of transcutaneous electric stimulation agrees with this. They report that placing the electrodes distal (below) the site of injury was generally irritating. However, my own experience with neuropathy (another kind of nerve pain) is that distal placement works well, however I will criss cross the electrodes placing one electrode on the right foot and the other from that same channel on the left such that the simulation runs very deep, up one leg and back down the other. Also in several of the settings described above in the more recent papers they were putting the electrodes both proximal and distal to the painful area, which I think also makes sense and seemed to work really well. With the above and below method, I would expect the proximal electrode to lessen any discomfort imparted by the distal electrode and the amount of stimulation coursing through the injured area to be greater, hopefully leading to better results. So I think in treating a person with CRPS you just don’t want to be dogmatic, you want to have a number of ideas (regarding where to put the electrodes, how many electrodes to use, how to program your machine, and how often and how long to apply the stimulation) to try and experiment with several before deciding on what’s best in general and for a particular person. Also these guys noted that the electric stimulation sometimes gave the pain relief necessary so that the people could begin physical therapy immediately afterwards. So I would think that’s the way to go, TENS or EMS first, with exercise afterwards in the pain reduced afterglow of electric stim, or perhaps sandwich physical therapy exercises between EMS and TENS sections, such that the electric stimulation could again be used to bring down pain that might have been increased with exercise. For most orthopedic conditions I do both EMS or TENS afterwards, but I did have a stroke patient with terrible neuropathic pain in her leg that put her in a wheelchair. This was early on as I was really starting to learn the ins and outs of EMS. I said to her we could try EMS (I did a 10-50-10 program on her) first and I think you’ll either really love it or really hate it. It turned out she loved it, and was able to walk with a cane immediately afterwards. She got a stimulator for home off ebay and fully recovered her ability to walk within 2-3 weeks. After that I thought, maybe I need to have these things on hand.
Anyways, that’s my comments for now. I’ll add to this review as I find new papers or have more first hand observations to add.
As always, thanks for reading my blog. While not all my blogs are about electric stimulation a good number of them are, with low back pain being another favorite topic of mine, and for which in my office I almost always use EMS as part of the treatment. So I get a lot of questions about what EMS/TENS machines are best. I haven’t tried them all, but the sweet spot for both performance, price, custom programmability is the Globus Genesy 300. On a budget the EV-906 is good, programmable and what I started with but not as powerful or user friendly as the Globus. If a two channel stimulator is all you need (and for CRSP it might be) I’m really liking the TwinStim4. I’m sure it’s a little self serving that I promote the one I sell, but if you read my notes from my year of EMS you’ll see I’m selling the one’s I think are best. Since there was no one stop shop that sells the machines I like, with the the pads and straps I like, I started my own. In fact I had to get my straps custom made and order 1000 of them to get any kind of discount. So I hope they sell, haha. So check out my shop.
Also if you need hands on physical therapy in the North Phoenix or North Scottsdale area be sure to make an appointment. Otherwise feel free to comment or ask questions here.
Chad Reilly, Physical Therapist