Chronic pain affects more than 116 million people in the United States and costs an estimated $635 billion annually in direct treatment and lost productivity.1 Pharmacologic agents to treat pain are often associated with side effects, and the overuse of opioid analgesics has become a public health safety issue. These frustrations prompt careful consideration of nonpharmacologic approaches to pain.
The Calmare Scrambler Therapy System is a 510(k)-cleared noninvasive pain therapy device to treat neuropathic and cancer-related pain. The mechanisms by which scrambler therapy relieves pain are not completely understood. The system uses a multiprocessor to synthesize 16 types of nerve action potentials that are similar to endogenous nerve action potentials. It strings these potentials into sequences and delivers electrical stimulation to the affected region. By mimicking endogenous action potentials, the device is able to "scramble" or modify abnormal pain signaling into non-pain information. The charge used in scrambler therapy is low, the waveform is constantly changing, and the electrical current is below the threshold that causes pain.
In comparison, electrical stimulation administered by a transcutaneous electrical nerve stimulation (TENS) device blocks pain signals after they are transmitted by sensitized nerves and has a much higher charge with a simple biphasic wave. Other chronic pain therapies, such as spinal cord stimulation and intraspinal drug delivery systems, involve invasive and expensive technology with the possibility of serious complications.
Scrambler therapy has been used to reduce pain associated with chemotherapy-induced peripheral neuropathy (CIPN), phantom limb syndrome, postsurgical neuropathic pain, chronic neck and low back pain, sciatica, failed back surgery syndrome (FBSS), brachial plexus neuropathy, reflex sympathetic dystrophy, and postherpetic neuralgia (PHN).
Due to the electrical current used in scrambler therapy, it is contraindicated in patients with pacemakers, automatic defibrillators, aneurysm clips, vena cava clips, skull plates, intraspinal drug delivery systems and undiagnosed pain. Patients with epilepsy should be treated with caution, and pregnant women or patients who have had a myocardial infarction in the past 6 months should not receive scrambler therapy.
Safety & Efficacy
The safety and efficacy of scrambler therapy was established in several trials. One of these enrolled 226 patients with chronic pain due to FBSS, trigeminal neuralgia and complex neuropathies.2 Of these, 80% said they experienced greater than 50% pain relief, 10% said they experienced pain relief of 25% to 49%, and 10% had no response to therapy.
In a subsequent study, Smith and colleagues3 assessed the efficacy of scrambler therapy among 16 patients with chemotherapy-induced peripheral neuropathy (CIPN), a dose-limiting side effect of antineoplastic agents. The primary endpoint, a reduction in pain score of 20% by the end of the study, was met by 15 of the 16 patients (94%). Mean pain scores dropped from 5.81+1.11 before treatment to 2.38+1.82 at the end of 10 days.3 Most patients experienced a gradual return of pain to pretreatment levels 1 or 2 months after treatment ended. However, pain levels decreased again when patients received a one-time re-treatment.
Scrambler therapy was also tested in 73 patients with cancer and noncancer-related pain whose pain management was unsatisfactory.4 Patients were eligible if they had a pain rated 5 or higher despite pain therapy, or if they were experiencing unsatisfactory pain relief with their current treatment. Ten 30-minutes sessions were administered to each participant. Mean pretreatment pain scores were 6.2+2.5, which decreased to 1.6+2.0 after the 10th day of treatment and 2.9+2.6 after the second week of follow-up. At 1 month after treatment, 81% of the study group had responded to therapy (73% complete, 8% partial) and 19% had not. Differences in response were not statistically significant in terms of pain diagnosis, duration or characteristics.
More recently, Marineo and colleagues5 performed a randomized, controlled trial of scrambler therapy (n = 26) compared to current guideline-based drug treatment (n = 26). The study enrolled patients with postsurgical or postherpetic neuralgia or spinal cord stenosis who had a subjective pain score of 6 or higher for at least 3 months despite treatment. While all participants received standard treatment following European Federation for Neurological Societies guidelines, the control group was allowed to start on different pain medications whereas the scrambler therapy group continued prior medications with no changes. Participants were assessed for pain intensity at baseline and each month thereafter up to 3 months. The scrambler therapy group received a 45-minute daily treatment for 10 consecutive days.
The VAS pain score in the control group fell by 28% at 1 month, and the scrambler therapy group VAS score dropped by 91%. Significant pain reduction was observed in all subgroups.5 Reduction in allodynia and pain medication dosages were also significant in the scrambler therapy group. At 3 months, opioids were totally eliminated in 11 of 17 cases, anticonvulsants were eliminated in 17 of 24 cases, and antidepressants were eliminated in 9 of 19 cases. At 3 months, more pain relapses were reported by patients who had polyradicular pain, but after retreatment, the pain scores decreased.
Implications for Care
Although these studies have provided impressive results, no blinded studies have been conducted and little information exists on long-term outcomes. Studies to address the possibility of a placebo effect are under way.
A particularly interesting aspect of scrambler therapy is the observed pain reduction in a wide spectrum of chronic pain etiologies, suggesting that effective treatment may depend more on the synaptic patterns assumed by the nervous system than the type of injury.
Cost is another consideration, since most insurance companies do not pay for scrambler therapy at this time. Many clinics that provide scrambler therapy are charging on a cash-for-service basis in the range of $100 or more per session. Each session includes an examination by a clinician certified in Calmare technology, application of the electrodes and a 30- to 60-minute treatment. It is recommended that patients receive 10 to 12 treatments over consecutive business days or until the pain resolves.6
Significant start-up costs are associated with scrambler therapy - for the device purchase and for training of personnel. Some practices use a trained technician to monitor therapy once the electrodes have been placed and the dial is set to the most effective level by the clinician.
Case Study 1: A 27-year-old man was diagnosed with non-Hodgkin's lymphoma. During the course of his treatment, he received chemotherapy that resulted in painful chemotherapy-induced peripheral neuropathy (CIPN) of the hands and feet. He tried several medications for the CIPN, including pregabalin, gabapentin and hydrocodone, but none worked satisfactorily and he discontinued them. After learning that he was in complete remission, he was anxious to resume work as a dentist. However, he found it difficult to feel his instruments. He described the pain as a constant burning discomfort in his hands and feet, with "pins and needles" in his hands. He rated the pain as 6 out of 10 in intensity.
The physical examination found diminished detection of pressure and temperature on the palmar surface of his hands and plantar aspects of his feet bilaterally. He also had a significant decrease in his ability to discriminate sharp and dull stimuli on the hands and feet on both surfaces. He had full range of motion with slight weakness of the interosseous muscles of both hands. Deep tendon reflexes were normal. I prescribed scrambler therapy for 10 treatment cycles or until the pain was relieved. The electrodes were placed on his lateral and medial forearms above the level at which his sensation was reduced. On his lower extremities, the electrodes were placed on the lateral aspect of each leg above the lateral malleolus and the dorsal aspect of each foot. After the first treatment, the patient commented that it was the first time since his cancer treatment that he was able to feel the tips of his fingers. After seven more treatments, he had complete relief of pain and was discharged from therapy.
Case Study 2: A 52-year-old woman received a prescription for scrambler therapy to treat persistent low back pain. She reported being thrown off a horse 2 years earlier and had experienced constant daily pain since that time. MRI of the lumbar spine demonstrated diffuse degenerative disc disease, but she did not have any vertebral movement on flexion/extension x-rays. Recommendations from neurologic and orthopedic surgeons entailed conservative measures for disc degeneration. She was adherent to following the exercises provided by physical therapy and saw a massage therapist, but she still rated her usual pain level as 8 out of 10. She was taking morphine extended-release tablets, gabapentin and celecoxib daily. Her gabapentin was titrated down and discontinued before starting scrambler therapy, since these agents interfere with achieving the full therapeutic effect of therapy.
On exam, the patient's sensation, motor strength and deep tendon reflexes were normal. Lumbar flexion was nonpainful to 40 degrees, but extension was impossible due to the pain. The most painful area of her lumbar spine on palpation was around the L3 area. The electrodes were placed outside the painful area in dermatome L2 and on the opposite side of the painful area in dermatome L4.
Following her second treatment, she was able to lie on her back for the first time in more than a year and to decrease the morphine dose to once a day. By the end of her tenth treatment, she rated her pain as 2 out of 10 and was only taking celecoxib. When she followed up 6 weeks later, she reported that she was able to exercise regularly without pain and was no longer taking the celecoxib on a regular basis.
1. Institute of Medicine. Relieving Pain in America: A Blueprint for Transforming Prevention, Care, Education and Research. Washington D.C.: The National Academies Press; 2011.
2. Sabato AF, et al. Scrambler therapy. Minverva Anestesiol. 2005;71(7-8):479-482.
3. Smith TJ, et al. Pilot trial of a patient-specific cutaneous electrostimulation device (MC5-A Calmare) for chemotherapy-induced peripheral neuropathy. J Pain Symptom Manage. 2010;40(6):883-891.
4. Ricci M, et al. Managing chronic pain: results from an open-label study using MC5-A Calmare device. Support Care Cancer. 2012;20(2):405-412.
5. Marineo G, et al. Scrambler therapy may relieve chronic neuropathic pain more effectively than guideline-based drug management: results of a pilot, randomized controlled trial. J Pain Symptom Manage. 2012;43(1):87-95.
6. Competitive Technologies, Inc. Recommended treatment protocol. www.calmarett.com/media/pdf/Treatment%20Protocol.pdf
Angela R. Starkweather is an acute care nurse practitioner who is a member of the nursing faculty at Virginia Commonwealth University in Richmond, Va. She has completed a disclosure statement and reports no relationships related to this article.