According to the Centers for Disease Control and Prevention (CDC), approximately 7 percent of the population in the United States has diabetes mellitus. Approximately 30 percent of patients with diabetes over the age of 40 have some kind of impaired sensation of the foot. Sensorimotor neuropathy is the primary risk factor for developing a diabetic foot ulcer, which leads to 85 percent of diabetic lower extremity amputations.1
Sensory neuropathy causes paresthesia and loss of protective sensation, which can lead to ulcerations and lower extremity amputations. Motor neuropathy causes imbalance, leading to injuries and fractures. Some of these injuries and/or fractures may force the patient to lose his or her independence. Autonomic neuropathy can lead to skin ischemia and Charcot events.
Overall, peripheral neuropathy decreases the quality and length of life for our patients. This nerve disease affects millions of Americans and can cause multiple foot and ankle disorders.
In addition to encouraging patients with peripheral neuropathy to modify risk factors, physicians have tried a variety of treatment options ranging from supplements and topical treatments to transcutaneous electrical nerve stimulation (TENS) units and monochromatic infrared light energy (MIRE). Historically, however, non-invasive treatment options have only shown mild to moderate success. Most of these options treat the symptoms but fail to treat the disease.
While there are a variety of oral medications, there may be concerns about possible side effects and/or polypharmacy issues. Surgical nerve decompression remains controversial. When it comes to addressing the symptoms of peripheral neuropathy, we may want to consider whether waveform electrostimulation has an emerging role within our armamentarium.
Weighing The Pros And Cons Of Medications For Diabetic Peripheral Neuropathy
In regard to patients with diabetic peripheral neuropathy (DPN), the most common treatment is oral medication. According to Berger, 53.9 percent of patients with DPN were treated with opioids; 39.7 percent with antiinflammatory drugs, 21.1 percent with serotonin selective reuptake inhibitors (SSRI) such as duloxetine (Cymbalta, Eli Lilly); 11.3 percent with tricyclic inhibitors (TCAs) such as nortriptyline; and 11.1 percent with anticonvulsants such as gabapentin (Neurontin, Pfizer) and pregabalin (Lyrica, Pfizer).2
Despite the cause of the peripheral neuropathy, most physicians treat their patients with the same treatment modalities as those they would use for DPN. A study of approximately 200 patients with DPN utilizing TCAs noted only a modest improvement of symptoms versus placebo.3 When comparing TCA medications versus SSRIs, the authors of another study stated that TCAs were less tolerated but more effective than SSRIs.4
Cohen and Susanne performed a study utilizing ibuprofen (600 mg four times daily) and sulindac (Clinoril) (200 mg twice daily). In this study, 18 patients with DPN demonstrated significant statistical reduction in paresthesias. However, using this type of medication has its drawbacks. The risk of renal impairment and gastrointestinal bleeding, in patients with diabetes as well as healthy patients, is well documented with long-term use of non-steroidal antiinflammatories.5
Tramadol (Ultram) tends to be a common choice for treating DPN due to its dual action of analgesic and serotonergic properties. A study of 131 patients with DPN demonstrated that tramadol facilitated a significant reduction in pain in comparison with the placebo.6-8 Researchers also have shown that opioid analgesics provide moderate relief of diabetic sensorimotor neuropathy. Adverse effects could include constipation, nausea, sedation and physical dependence.8
Finally, while newer drugs such as duloxetine and pregabalin offer safe and effective modalities to decrease the symptoms of painful DPN, they do not reverse nerve damage.9,10
Is Diabetic Nerve Decompression A Viable Treatment Modality?
Another approach to counteract DPN is surgical nerve decompression. In Podiatry Today, Barrett discussed the success of decompressing affected nerves.11 Mahoney reported on performing 200 nerve decompression procedures for patients with diabetes and reportedly had an overall success rate of 88 percent.12
However, in a 2003 Podiatry Today roundtable discussion, Boulton denounces surgical decompression for diabetic peripheral sensory motor neuropathy, emphasizing that this type of neuropathy is not an entrapment neuropathy.13 DeHeer points out that the research on surgical decompression has largely been performed by affiliates of the same institute.11
Can Non-Invasive Devices Have An Impact?
Anodyne® (Anodyne Therapy) is one of the first non-invasive devices introduced to the market for the treatment of peripheral neuropathy. This FDA-approved device uses monochromatic infrared light energy (MIRE) to increase circulation and decrease pain. In Leonard’s study, results showed a decrease in pain for patients with DPN.14 Recently, Lavery stated that the study performed by Leonard, et al., lacked statistical quality. Lavery also claims the intent to treat strongly influenced the studies by not showing negative results from the patients involved in the studies.15 Currently, Medicare and other insurances companies do not reimburse for this kind of therapy.
Recently, another device has been introduced into the market. MicroVas® (NeuroVasix) is also a non-invasive, FDA-approved device, which utilizes a magnetic waveform to increase blood flow and oxygenation in the area. A preliminary report conducted by Harkless, et al., revealed a lasting reduction in pain and increased sensation of the lower extremities in a study of 20 patients with diabetes. No statistical analysis has been provided as of yet.16
In the past, physicians have utilized electrostimulation with a biphasic exponentially decaying waveform to treat DPN. One study examined 26 patients who first received amitriptyline to see if symptoms subsided. Twenty-three of the 26 patients who received some relief or did not respond to the medication received electrostimulation or a sham therapy. These patients continued taking amitriptyline. Treatments were self-administered for 30 minutes daily for 12 weeks. Of the 14 control group patients who received dual therapy, 11 showed improvement of their symptoms. However, the patients’ symptoms returned soon after the electrostimulation treatment ceased.17
What One Retrospective Analysis Reveals About A New Waveform Device
Now the VST Myodynamic Device® has emerged for the treatment of peripheral neuropathy. The new modality uses a pure, alternating, biphasic, sinusoidal waveform (VST waveform). In order to determine the efficacy of this device, we developed an office-based protocol for a retrospective analysis.
For the study, we included the first 40 consecutive office patients who met the following criteria:
• a diagnosis of any form of peripheral neuropathy either by a neurologist, another physician, or the researchers themselves during their initial clinical exam; and
• the presence of painful peripheral neuropathy in the lower extremity.
We diagnosed 22 patients with DPN, 16 with idiopathic peripheral neuropathy, one with chemo-induced peripheral neuropathy and one with alcohol-induced peripheral neuropathy. The patients’ age range was 35 to 87. The number of months each patient experienced PN symptoms ranged from four to 240 with a mean number of 67 months. Using the VAS pain scale, the patients’ subjective pain from peripheral neuropathy ranged from 1 to 10 with a mean of 5.9. Forty-two percent of the patients were actively taking medicine commonly prescribed to treat the symptoms of peripheral neuropathy.
All patients received the treatment at least twice every week and all had to complete the treatment regimen, which varied from 12 to 40 sessions depending on the severity of the peripheral neuropathy and the patient’s individual response to the therapy. During this study, we did not encourage patients to stop taking anti-neuropathic medication previously prescribed by other physicians nor did we provide any new prescriptions (including supplements or vitamins).
In 2006, patients began receiving VST waveform electrostimulation two to three times a week in our offices. We used four electrode pads, which were controlled by two channels on each lower extremity. The two pads connected to the first channel were over the fibular head and the anterior ankle. The second channel’s pads were posterior-superior to the medial malleolus and across the plantar metatarsal heads. Each therapy session lasted one hour.
After completing the entire therapy regimen, each patient received an exit questionnaire. The questionnaire consisted of the following questions:
• What is your current pain level (on the VAS scale) for your lower extremity peripheral neuropathy symptoms?
• What other benefits have you noticed from your therapy?
• What is the percentage of overall symptom improvement in the lower extremity after going through VST waveform therapy?
• Would you recommend this office therapy to another patient?
We compiled the data from these 40 patients and did a retrospective analysis. We noted a final mean peripheral neuropathy pain reduction of 83 percent with an overall symptom improvement mean of 86 percent. There were other benefits as well. A majority of the patients had a significant improvement in the quality of sleep, improved balance during gait and increased lower extremity sensation. Many of the patients on anti-neuropathic medication during the study had either stopped taking the medicine, decreased their dosage or were planning on talking with the prescribing doctor about eliminating the medication.
The VST waveform therapy required a mean of 24 office sessions. All study participants noted they would recommend this type of therapy to another patient. Study authors noted no adverse events during the treatment. There was no significant statistical difference between either researcher’s final outcomes.
Indeed, VST waveform therapy can significantly reduce lower extremity peripheral neuropathy symptoms and seems to reverse some nerve damage. Pain, foot sensitivity, sleep cycle, balance and quality of life improved in this small patient population. One can only assume these improvements may lead to fewer ulcers, amputations and falls.
While the VST waveform showed good results immediately after therapy, the long-term impact is unknown. Of the participants in this analysis, we did see 16 out of the 40 patients again after the VST waveform study for unrelated problems. Each of the 16 patients reported no relapse of pre-treatment symptoms. The average amount of time between the end of VST therapy and the unrelated follow-up visit was about five months. We do acknowledge that there was no meaningful statistical design or analysis in this study. Further research is needed to gauge long-term results.
Peripheral neuropathy is a serious condition and its effect on the lower extremity can be devastating. Researchers need to look for treatment options that not only decrease paresthesia but reverse nerve damage, decrease life-changing outcomes and improve one’s quality of life.
In our experience, VST waveform therapy is a viable option for meeting some of these goals in treating painful peripheral neuropathy.
Dr. Abdo practices at St. Louis Foot and Ankle in St. Louis. He also practices at Christian Northeast Hospital Wound Center in St. Louis.
Dr. Walker practices at Advanced Foot and Ankle Surgery in Denton, Texas.
Dr. Steinberg is an Assistant Professor in the Department of Plastic Surgery at the Georgetown University School of Medicine in Washington, D.C. Dr. Steinberg is a Fellow of the American College of Foot and Ankle Surgeons.
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