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12 Articles in Volume 12, Issue #1
Ask the Expert: Escalating Opioids
Can Yoga and Stretching Exercises Relieve Chronic Low Back Pain?
Cortisol Screening in Chronic Pain Patients
Editor's Memo: FDA Removes Homeopathic HCG; Helps Legitimate Use In Pain Treatment
Formulation: The Four Perspectives of a Patient in Chronic Pain
Guide to Chronic Pain Assessment Tools
How to Select an In-Office Electromagnetic Field Device
Letters to the Editor: Hormone Therapies
Managing Pain in Active or Well-Controlled Systemic Lupus Erythematosus
PPM Editorial Board Examines Steps to Prevent Accidental Overdoses
Saliva Drug Screening in the Office Setting: Detection of Drug Use and Abuse
Understanding the Toxicology of Diazepam

How to Select an In-Office Electromagnetic Field Device

Choosing an appropriate device often depends on the product’s ability to achieve certain clinical goals, such as reducing pain, inflammation, or muscle tightness.

Electromagnetic (EM) energy is inherent in most medical device applications today—whether for therapeutic or diagnostic purposes. The EM spectrum defines EM energy in terms of frequencies and wavelengths, the two being inversely related. For the purposes of this article, we confine our discussion to the non-ionizing part of the EM spectrum, which uses energy levels that do not break cellular chemical bonds (ionizing effects).

Much continues to be written about the possible adverse effects of low-frequency non-ionizing radiation exposure, with no clear consensus between commercial and government agencies on the one hand, and consumer watch groups and/or researchers on the other. Position statements by various stakeholders are published for the public purview but lack any semblance of an agreement or consistent scientific validation.1 One aspect of this discussion that everyone does seem to agree on, however, is that our population is being increasingly exposed to EM energy in its many forms—electric, EM, and electronic sources.

Setting the issue of population safety aside, from the clinician’s standpoint we are seeing a proliferation of new testing and therapy technologies that rely on EM energy to function and often convert electrical energy into another form of energy, such as sound or light, which is then emitted into human tissue for therapeutic purposes. The question then becomes, how do we select the appropriate EM energy–emitting device for use on our patients, given the myriad available devices in the marketplace today? This article provides an overview of popular and available technology categories that have demonstrated relative effectiveness and safety in the past (Table).

Cellular Electric Fields
It has been known for years that all human cells have an electric field across the cell membrane, but what was not recognized in the past is the existence of a very active internal cellular electric field that operates within living cells. Using nanotechnology tools, specifically voltage-sensitive dyes encapsulated in polymer spheres, researchers have identified the presence of very strong intracellular electric fields (15 million volts per meter)—stronger than those found in lightning bolts.2 This revelation helps provide a basis for examining cellular changes that occur in diseases such as cancer and diabetes, as well as perhaps providing practitioners with a new biomarker for measuring cellular health. Along with the idea of an internal cellular electric field is the corollary notion of a unique cell resonance or vibration frequency that also might be an indicator of cell integrity. Understanding that the human body is an electric entity, similar in electrophysiology to a large battery, might help set the context for an alternative perspective to tissue healing and pain management in general.

That the human body is indeed an electric entity is not in itself new. Researchers such as Robert Becker wrote extensively on the topic many years ago in The Body Electric and Cross Currents.3 What is new is some of the scientific research that helps validate this viewpoint, while at the same time raising the evidence standard for the concept of EM medicine. The cell is the structural and functional unit for tissues and organs, making these recent research findings fundamental in the discussion of potential EM energy effects on both human homeostasis and disease states. These discoveries will be important to clinician groups that are both understanding and supportive of EM influences on human bio-functions, as well as those who are naturally repelled by such notions of EM energy–induced bio-effects and rather place their beliefs primarily on chemical and pharmaceutical approaches.

Exposures and Limits
The human body appears to be both an acceptor and emitter of EM energy, suggesting that EM energy might be integral to how we function and live. Recognition of critical EM energy requirements as basic life criteria will lead naturally to a basis for both therapeutic approaches and possible new methods of testing. We already recognize that natural sources of EM exposures are essential to life—including sunlight (ultraviolet [UV] light) and its role in seasonal affective disorder, depression, sleep cycles, and vitamin D regulation.4

The more important question might be one of EM dosage or exposures. Although there is no consensus on how much is too much regarding cumulative (man-made plus natural) EM exposures or even a minimally effective dose, when aiming for a therapeutic effect in medical device applications, some would argue that even incidental exposures from such sources as microwaves and cell phones are too much, claiming EM energy “sickness” as a result. The implications of such findings would be quite significant and very difficult to rectify from a public health policy standpoint because there is a vast number of EM sources in existence today, including appliances, power lines, entertainment systems, computers, communication devices, and so forth. Although exposure level speculations abound, there has been no consistent, well-controlled research to support either position—even when investigating the effects of EM fields on self-diagnosed electromagnetically sensitive subjects.5

Skeptics will counter with the argument that our current cache of research evidence has been sponsored, to a large degree, by groups and agencies with a vested interest in maintaining the status quo. This viewpoint is difficult to simply ignore, because, after all, the control of random and artificial EM exposures would be a terribly expensive and cumbersome, if not an impossible, problem to fix, as well as perhaps embarrassing to those agencies that have refuted the notion of EM pollution leading to human health problems. There are a number of incidental sources of EM radiation that are generally considered to provide “background” exposure that cannot be avoided, such as sunlight (UV and infrared light), natural radioactive material contained in coal and granite, radon (leaking from the Earth’s crust), cosmic rays from space, and our own natural radioactivity emission from our bodies.6 At this time, researchers are unsure of any specific long-term effects resulting from prolonged (chronic) exposures to non-ionizing radiation.

Therapeutic Applications/Selection Parameters
Like most interventions we select for a specific patient or clinical problem, the criteria we often employ in choosing a therapy is predicated on a rationale linked to treatment goals. The field of electromedicine contains a vast array of possible interventions, and the number of specific treatment devices that are available is even greater. One approach to categorizing the various types of EM-emitting devices is to use a criterion set similar to the one used by the Food and Drug Administration (FDA) when it reviews submissions for new product approvals. The FDA classifies devices as Class I to IV depending on the level of radiation or photonic energy. Photons are packets of EM energy and apply equally when referring to light or radio waves, x-rays, and gamma rays. The frequency or wavelength and emission durations are central in the FDA classification system for EM energy devices, with average power levels also factoring into the equation. The total exposure energy is calculated and expressed as joules per centimeter squared (J/cm2), using an example in conventional phototherapeutics. This method of assessing total energy emitted with a particular therapy might prove too cumbersome for many practitioners, and as such, an alternative method of dosimetry evaluation is recommended.

Additionally, simply assessing energy emissions in target tissue does not provide any meaningful information on energy deposition or expected clinical outcomes because photonic energy dosimetry does not necessarily follow a linear or even predictable dose–response relationship. In other words, we have no way of knowing the incremental effects of escalating dosages using the same energy source, much less comparing energy dosage delivered by different forms of EM radiation (sources), such as sound, light, electrical, and mechanical emissions. Well-researched and reliable source exposure energy conversions simply are not available at this time.

Selection Parameters—How Do We Choose?
Generally, the selection of an EM device depends heavily on the objective the clinician is attempting to achieve. In the United States, the level of insurance reimbursement associated with a modality has been implicated as an important factor that often contributes to modality use. This is unfortunate but not completely unexpected in a health care system in which supplier-induced demand continues to operate at various levels.

When inflammation is the primary problem, the use of therapeutic ultrasound has been employed and continues to be popular. Ultrasonic energy is that above 20 KHz, with therapeutic ultrasound ranging from 1 to 3 MHz being approved for human applications (Figure 1). The use of diagnostic ultrasound ranges from 5 to 20 MHz, with the higher frequencies providing superior resolutions. In ultrasound physics, it is generally understood that the higher frequencies have more superficial uses, whereas the lower frequencies offer deeper penetration for organ scanning. In ultrasound and electrotherapy, frequencies determine depth of penetration, whereas in phototherapy, depth is determined primarily by the affinity between a chromophore molecule to a specific wavelength. Although there is an inverse relationship between an EM source’s natural frequency and wavelength, there is an external frequency, which can be controlled and adjusted to provide specific tissue effects. With most ultrasound delivery, the electrical energy from the wall outlet is converted into sound waves using a piezoelectric crystal contained in the probe that vibrates at a certain frequency. This causes sound wave disturbances at similar frequencies that are emitted into the target tissue. The resultant echoes are thought to cause micro-perturbations in tissue facilitating a natural micro-massage effect, leading to better fluid resorption.7 Ultrasound is safe and has accumulated an abundance of empirical evidence despite the paucity of well-controlled clinical trials.

Figure 1. Therapeutic ultrasound being applied to the knee.

Another EM source method used to remove excess fluid or tissue inflammation is electrical muscle stimulation (EMS), which is a more aggressive option than ultrasound and has certain advantages that sometimes makes it preferential for use (Figure 2). What is known about the use of EMS is that it has the most impact on swollen joints in conditions such as osteoarthritis and rheumatoid arthritis. Patients with joint swelling are at risk for falling because of reflex inhibition that occurs when joints have excessive (>2-3 mL for the knee) intra-capsular fluid. It is thought that reflex or arthrogenic inhibition is an event that occurs secondary to stretching of the joint mechanoreceptors and acts as a protective mechanism to ensure that people with joint injury do not further damage tissue through over-activity. In an effort to protect a joint that has an effusion, the peripheral nervous system inhibits the local muscles surrounding that joint, so minimal joint activity continues. This is seen especially in swollen knees, where the central nervous system can exert inhibition over the working quadriceps as a patient attempts to perform a maximal muscle contraction. With these controlling muscles basically shut down, joint and muscle strengthening becomes a challenge, and excessive joint effusion predisposes afflicted persons to higher risk for falls.8

Figure 2. Demonstration of electrical muscle stimulation to reduce inflammation.

The application of EMS can counter the effects of reflex inhibition. By combining an artificially induced electrical contraction with the person’s own maximal volitional muscle contraction, the end product is an even greater muscle action that is the summation of the two. The stronger the muscle contraction, the faster the swelling is milked out of the joint, and the faster the normal joint mechanics are restored.

Pain Management
When pain management is the primary goal in a treatment plan, clinicians often defer to a different set of EM-driven tools. Some of the more common devices include application of transcutaneous electrical nerve stimulation (TENS) or micro-current electrical nerve stimulation (MENS) to tissue for varying lengths of time. Both have unique and interesting postulated mechanisms of action. The TENS unit has been available for many years and continues to be a very popular modality. It is regarded as primarily a pain-masking device operating under the theoretical framework of the spinal gate, from where it can stimulate local pain sensory fibers, which, in turn, act to jam the spinal gates, effectively preventing pain signals from reaching cortical levels for processing. The gate theory of pain has been used to help explain proposed mechanisms of action for TENS units and is consistent with other commonly observed phenomena, including the effects of distraction and counter-stimulation in the treatment of pain.9 In any case, the application of TENS for perioperative and postoperative pain problems continues to be ubiquitous when a conservative, or patient-directed treatment method, is desired.

The MENS approach, or new-generation TENS, as it has been called, uses micro-currents to penetrate deep into soft tissue to exert its effects. The TENS modality uses milliamp-level current, whereas the micro-current devices operate in the micro-amps or millionths of amps. Both modalities are portable, relatively safe, emit ultra-low–level EM fields, and do not require special EM shielding to operate. The MENS devices operate at the cellular level, and there are in vitro and in vivo evidence that micro-current application can work at the level of the mitochondria to stimulate production of adenosine triphosphate. This potential re-energizing at the cellular level is an intriguing observation and has led to speculation and interest in the possibility of enhancing cellular metabolism and repair processes during injury states. As a result, clinicians tend to use MENS when there is tissue tearing through trauma, over-contraction, and/or an elongation-type injury. This makes it a popular choice in a sports medicine milieu.

Myofascial Tightness/Trigger Points
Many of the therapies listed have multiple applications, but categorizing all of these is beyond the scope of this clinical overview. We focus on some of the more popular sources of EM energy as they are applied to specific clinical problem sets. The use of interferential currents to normalize paraspinal muscle tension is well recognized among soft tissue specialists. The basic concept underlying this therapy is the application of two medium-frequency currents applied simultaneously (crisscrossing) to produce a low-frequency current that acts deep and central to the two applied currents. The first current is medium frequency and approximately 4,000 Hz (carrier wave) to maximize comfort relative to a lower-frequency and less comfortable current. The second current has a short medium-frequency range (4,001-4,150 Hz) and is not fixed in frequency, thus avoiding tissue habituation or accommodation. The end product current is a comfortable delivery of EM energy at approximately a 1-to-150-Hz frequency. This delivery mechanism takes advantage of lower tissue resistance with application of medium-frequency currents, but the resultant low-frequency end product is optimal for decreasing pain by reducing muscle tension levels.10

In many cases of soft tissue injury, there is a concomitant comorbidity in the form of trigger points (TPs). These hyperactive bundles of muscle tissue can act as relay stations for pain transmission and often are simply discounted as secondary manifestations of the primary injury. That being said, they can behave as primary generators of pain and soon overtake the primary lesion as the important source of tissue impairment. The application of cold laser therapy has been used to treat TPs and general myalgias for more than three decades in Europe and Canada and more recently in the United States since FDA approval of the first Class IIIb cold laser device in 2002 (Figure 3).



Figure 3. Cold laser trigger point therapy helps relieve painful soft tissue lesions.

Condition-specific cold laser stimulation parameters have not been well defined, despite manufacturers’ and laser proponents’ claims to the contrary. In defense of medical device companies, they lack the financial resources of their pharmaceutical counterparts, making it difficult to conduct large, multicenter clinical trials. As a result, many insurance carriers and policy makers are not yet convinced of the clinical value of this modality, and it remains unrecognized from a Current Procedural Terminology and/or federal payer standpoint.

Nevertheless, those clinicians who have experience with cold laser applications directly on patients remain steadfast that therapeutic effects are real and measureable. Application of cold laser energy directly into a clinically and ultrasonographically confirmed TP has been shown to eradicate painful soft tissue lesions and help restore normal tissue dynamics. The smaller aperture on certain laser wand probes makes TP ablation easy and comfortable for clinicians. Larger cluster probes can be used for larger areas requiring irradiation and can have similar positive tissue effects.

Enhancing Circulation
There are various forms of EM energy that may effectively increase or improve circulation in a target area, enhancing overall healing and possibly even stimulating neovascularization in a region devoid of adequate tissue perfusion. A relatively new approach to improving perfusion has been the introduction of currents that have their primary effects on lymphatic tissues and promote fluid reabsorption via lymphatic stimulation (Figure 4). Vascular pooling (stasis) has been implicated in the inflammatory cycle and can be especially problematic during sleep leading to painful engorgement in vascular beds. The use of H-wave stimulation targets this condition for amelioration through gentle application of tissue-specific electrical stimulation. The use of microwaves, pulsed EM energy, and diathermy all aim to reach deep soft tissue regions with the objective of increasing circulation by heating tissue.

Figure 4. H-wave stimulation targets deep tissue regions to increase circulation.

More recently, phototherapy has been applied to patients with diabetic neuropathy with the goal of improving circulation in the feet and/or hands, which could lead to improved sensation. Light-emitting diode infrared therapy and/or cluster laser probes also are used for this vexing clinical problem, which affects millions of people every year. Diabetic neuropathy is difficult to treat from any standpoint, and no universally effective medications are available to reverse the debilitating effects of severe neuropathy. It is thought that the primary pathophysiologic mechanism that underlies diabetic neuropathy is a microvascular collapse and that by stimulating vascular proliferation in these areas, symptoms will decrease and even improve over time. This explanation is overly simplistic and does not elaborate on the cascade of biochemical events leading up to circulatory collapse, but rather identifies the end result and how it can be conservatively countered using perfusion-inducing conservative treatments aimed at correcting the primary manifestation of diabetic neuropathy.

Miscellaneous Effects
There will be myriad physiologic targets that EM energy devices can affect, including the application of direct current for peripheral nerve palsies such as facial or trigeminal nerve paralysis. The stimulator is shaped like a handheld gun with a probe extension and small tip to better localize over the nerves and apply short bursts of direct current. Application of electrotherapy techniques abound, but recently an electrical application that specifically targets the lymphatic tissue to enhance swelling and clear areas of vascular engorgement has been an elegant addition to the arsenal of EM energy devices. The H-wave stimulator has two primary applications: swelling and pain. The waveforms are tailored specifically for each application. Deep electrical stimulation when applying acupuncture has provided excellent analgesia for many years. Percutaneous electrical stimulation can target specific soft-tissue targets that are deeply situated, allowing clinicians to reach areas they could not in the past. Current-conducting acupuncture needles are placed strategically into painful areas (Western acupuncture) using mechanical constructs and/or into traditional acupuncture points on a meridian (Eastern acupuncture) using a traditional Chinese medicine construct. EM energy sources are used for transdermal drug delivery in iontophoresis and electrical wave conversion to sound energy. The energy inherent in a sound wave is used to drive steroid molecules into tissue during phonophoresis applications.

The use of EM energy is growing rapidly, and there are concerns about the relative risk these exposures create. For the most part, research has not identified concrete adverse effects from incidental exposures, including epidemiological data. The therapeutic application of devices that employ EM energy needs to be evaluated from a similar perspective, with risk assessment paradigms being applied to clinical settings as well as the environment. More research is needed into how human physiology is affected by varying levels of EM fields used in medicine and rehabilitation within the greater context of total environmental exposures so that a more comprehensive risk assessment can be completed.

The use of EM energy can take many forms, and practitioners are encouraged to use a goal-oriented approach to systematically evaluate the use of a particular technology for their patient population. Product selection based solely on energy emissions can be an incomplete endeavor, because energy source conversions are not readily available. The selection of products probably will be driven primarily by the capability of the device to achieve certain clinical goals such as reducing pain, inflammation, and spasm/tightness; and/or improving sensation/perfusion and lymphatic flow.

Last updated on: February 16, 2012
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