The first trial was authored by the Scrambler Therapy developer, Marineo, in 2003 and reported the results of the treatment of 11 patients with cancer-associated, drug-resistant, visceral pain. This manuscript noted that pain was quickly and markedly reduced in the studied patients, with 9 of 11 patients stopping the use of pharmacologic pain therapy altogether after the first five sessions, without any associated side effects. Pain scores were reported to have decreased from approximately 8.5 out of 10, at study initiation, to approximately 0.5 out of 10, after 10 treatments. No adverse effects were reported.
A second trial was published in 2005, with Marineo as a co-author. A total of 226 patients with neuropathic pain were treated, including patients with failed back surgery, brachial plexus neuropathy, and other chronic pain conditions. This trial, while also uncontrolled, was impressively large and reported that 80 % of subjects had at least a 50 % pain reduction and 10 % experienced a reduction of 25–49 %. Ten percent (10 %) had no appreciable response. No adverse effects were reported.
Additional groups became involved in the clinical evaluation of this therapy with the publication in 2010 of the first study that did not include Marineo as a co-author. This was a pilot trial in 16 evaluable patients with chronic chemotherapy-induced peripheral neuropathy, conducted at Virginia Commonwealth University. The findings from this study were in line with the success seen with the previously reported trials. After ten treatments, the average reported pain score dropped nearly 60 %, with four patients achieving complete resolution of pain. Patients with recurrent pain successfully retreated with 1–3 subsequent treatments.
The next trial, currently only available as an abstract, involved ten patients with failed back surgery treated by an anesthesiology-trained pain physician. While it only noted a 28 % mean pain reduction, there were patients on this trial who had substantial relief after multiple other therapies had failed to provide benefit. The author of this abstract, a coauthor on the present manuscript, notes that there are three reasons why his success rate might have been relatively low: (1) he had limited operator experience; (2) he included study subjects with multifactorial intractable pain despite intensive polypharmacy; and (3) treatment while adjuvant anticonvulsants were continued. Empiric observations have suggested less than optimal outcomes if these medications are not discontinued prior to treatment.
Marineo and colleagues published the first randomized, controlled trial in 2011, which involved 52 patients with chronic neuropathic pain related to postsurgical causes, post-herpetic neuralgia, or spinal cord stenosis. Scrambler Therapy was compared to a control arm that utilized standard pharmacologic guideline-based recommendations, including frequent phone calls to modify analgesics. The pain reduction, after finishing 10 days of treatment, was 28 % in the control group (pain scores dropped from 8.0 to 5.8 out of 10) compared to a 91 % reduction with the Scrambler group (pain scores dropped from 8.1 to 0.7; p < 0.0001). Pain scores in the control arm were 5.7 and 5.9 at 2 and 3 months, respectively, as opposed to 1.4 and 2.0 in the Scrambler group (p < 0.0001). Analgesic consumption, including opioids, antidepressants, and anticonvulsants, decreased by 72 % in the Scrambler group. Allodynia also was reduced in the Scrambler patients, from 77 % at baseline to 15 % at 3 months. The benefit was obtained relatively equally amongst patients of all of the three diagnostic categories.
The sixth trial involved 82 (73 evaluable) prospectively-treated patients, about half of whom had cancer-related pain. Mean pain scores reduced from 6.2/10 before to 1.6/10 at the end of treatment and were 2.9/10 1 month after treatment was finished. Similar results were seen in patients with and without cancer. When patients were asked whether they would repeat this treatment, 97 % (71/73) responded affirmatively.
The seventh trial involved a cohort of eight patients treated with Scrambler Therapy for chronic low back pain. Patients were treated for six consecutive days; pain scores were recorded prior to initiation of treatment and after each session. The mean pain score was 8.12/10 at baseline, dropping to 6.93/10 after the first treatment. The mean pain score dropped to 3.63/10 in day 6. The group also recorded the Oswestry Disability Index (ODI) and found that mean score dropped from 49.88/100 to 18.44/100 by the end of the study, signifying an average drop from severe to minimal disability.
The eighth investigation was a prospective trial that reported on a series of 39 patients with cancer pain syndromes, including 33 with chemotherapy-induced peripheral neuropathy. Scrambler Therapy was associated with significant positive changes from baseline for a large number of outcomes, including degree of pain, interference with normal activities, and sensory neuropathy symptoms. The benefit persisted up to 3 months.
A small prospective trial published in 2013 involved 10 patients with post-herpetic neuralgia and included some data previously reported in another publication. The work reported a 95 % reduction in pain scores at 1 month, with sustained benefit observed at 2 and 3 month follow-up times.
In 2014, a prospective pilot trial experience was published, involving the treatment of 37 patients with chemotherapy-induced peripheral neuropathy, noting about a 50 % reduction in pain, tingling, and numbness. The increase in Scrambler benefit over the course of the trial suggested that, despite initial operator training in the administration of Scrambler Therapy, a learning curve was evident in this trial. The last 25 % of patients entered on this clinical trial did substantially better than did the first 25 % of patients, likely a reflection of improved technique afforded by greater experience.
The first attempt to compare Scrambler Therapy to a sham control was presented as an abstract at the 2013 Annual Meeting of the American Society of Clinical Oncology, involving 14 patients who were treated in a randomized, controlled, and double-blind manner. Results from this study have not been published as a manuscript. While the authors did note that the sham treatment from this particular trial was believable, in that the patients could not more often detect which of the two procedures was the true one, the authors did not observe any real improvements in neuropathy in the patients treated with the sham procedure versus Scrambler Therapy. This may well have been because this group had little experience with the technique prior to conducting their study. This finding fits with above-noted work that observed that there is a learning curve for the appropriate application of this therapy for treating chemotherapy neuropathy, which likely also applies to the treatment of other conditions. Additionally, the results of this trial support that there was not much of a placebo effect in this trial, as no benefit was noted in either trial arm. Paradoxically, this would support the argument that the positive results reported in other chemotherapy neuropathy Scrambler Therapy trials are not just ascribable to a placebo effect.
In 2015, a single-blind, sham-controlled, randomized clinical trial involving 30 patients with low back pain was reported from Virginia Commonwealth University. These authors noted significant decreases in the Brief Pain Inventory (BPI) back pain scores and pain interference scores (P ≤ 0.05). They also noted improvements in pain sensitivity, as measured by participants’ thresholds for pain in the initially painful area. Of note, the group randomizedtoScramblerTherapyhadsubstantialdecreasesin10 serum messenger RNAs (mRNAs) associated with nerve pain such as nerve growth factor (NGF) and glial derived nerve factor (GDNF), compared to no decreases in the sham group, understanding that these mRNAs have not yet been established as correlates for pain.
More recently, two subsequent single-arm prospective trials have been published which support therapeutic benefit. A pilot study was reported from an Italian hospital, evaluating outcomes of Scrambler Therapy in 25 patients with pain related to bony and visceral metastases. Each patient was scheduled for 10 daily sessions of treatment, and pain outcomes were measured by the use of a numeric pain scale. All patients were reported to have experienced at least a 50 % decrease in pain scores, with a mean pain score of 8.4 at baseline dropping to 2.9 after completion of the treatment course. The average duration of “pain control” (defined as >50 % reduction from baseline pain score) was 7.7 +/− 5.3 weeks. Sleep performance was also noted to improve significantly for the cohort. In Korea, Lee et al. performed an open-label, single-arm, exploratory study involving 20 patients with CIPN, metastatic bone pain, and postsurgical neuropathic pain. Pain scores decreased significantly, as did consumption of rescue opioid medication.
Clinical Practice Experiences
Two case series, published in 2013, each included three patients with cancer pain or post-herpetic pain. Both of these reports came from different authors and both reported positive benefits in the patients who were treated.
Sparadeo et al. reported their clinical practice experience regarding 91 of their initial 173 patients, representing all of those for whom they had collected data. These patients had a variety of pain syndromes, including CRPS, spine pain, neuralgias (such as post-herpetic or post-chemotherapy), and multi-focal pain problems. As part of their practice, with these 91 patients, they collected visual pain scores before and after each treatment for all of them and BPI questionnaires, in a subset of them, prior to treatment initiation and at 3- and 6-month follow-up times. The mean pain score prior to the first treatment was 7.2/10; it was 3.0/10 on the 10th day, prior to that day’s treatment. Relatively similar results were seen for the different pain syndromes. BPI scores at 3 to 6 months of follow-up were reported to be improved by more than 50 %.
In a second manuscript, Sparadeo and D’Amato analyzed the pre- and posttreatment data of 95 individuals (some of whom had been reported in the previous publication) entering their Scrambler Therapy program for treatment of chronic neuropathic pain, divided into two groups: CRPS and chronic spine-based pain. All patients were weaned from opioids and anticonvulsants being used for pain control. The data analysis revealed that 70 % of the entire sample was still reporting significant improvement 3 to 6 months following treatment. The two studied groups had similar levels of pain and degrees of lifestyle impact. Additionally, the 3–6-month successes were similar in the two treatment groups.
Another clinical practice experience report involved 147 patients treated at two United States military sites and one South Korean site. They noted that 38 % of patients had at least a 50 % pain reduction that lasted for more than a month.
Does Scrambler Therapy actually work?
Arguments against Scrambler Therapy certainly exist, with critics attributing much of the benefit to a placebo effect. Some of the positive endorsements in social media and on the Internet are only anecdotal. Additionally, the developer of Scrambler Therapy participated in the initial clinical trials, and this could be perceived as a potential conflict of interest even though it is scientifically desirable and logical to expect the device inventor to report the first set of results. Additionally, some of the reports claim that there is a phenomenal benefit that lasts for a long time, which sounds too good to be true. Lastly, there are no large, placebo-controlled, double-blinded clinical trials to estimate the effectiveness of Scrambler Therapy.
On the other hand, while some reports involved the inventor of the Scrambler device, these positive findings have been independently replicated by diverse groups in nearly all of the reported studies, involving over 900 patients in total. In some cases, the benefit achieved has been substantial, with some patients achieving complete pain resolution and substantially reduced dependence on pharmacologic therapy. There has been only one report of a negative experience. This was from one small, placebo-controlled trial in patients with chemotherapy-induced peripheral neuropathy. This was published only as an abstract, did not show much of a reduction in either study arm (arguing against a placebo effect), and was produced by a group that did not have much experience using Scrambler Therapy. This raises concerns regarding the validity of this trial, as data have supported that there is an extended learning curve with the provision of Scrambler Therapy, particularly for chemotherapy-induced neuropathy . At the same time, it must be noted that although this is the only negative trial published on Scrambler Therapy, the possibility of publication bias cannot be excluded. Negative experiences may not be put into publication form for various reasons, and so the currently available literature may be overestimating the positive experience with this technology.