Transcutaneous Electrical Neural Stimulator (TENS)
TENS is the acronym for "Transcutaneous Electrical Neural (or Nerve) Stimulation". The small electrical currents of TENS are adjusted to send stimulating pulses over the surface of the skin and into nerve endings. Those pulses help to decrease pain by blocking pain signals from reaching the brain. They also help stimulate production of endorphins, the body's natural painkillers. Common uses for TENS: back and neck syndromes, RSD (or "complex regional pain syndrome"), arthritis, shoulder syndromes, neuropathies, and other acute and chronic pain.
Developed in the late 1960's, this type of stimulator is characterized by biphasic current. ("Biphasic" refers to two phases, or pulses of 2 different intensities alternating with each other - not to be confused with "alternating current" or bi-directional current flow.) Most stimulators feature adjustable settings to control amplitude (intensity) of stimulation by controlling voltage, current, and pulse width (duration) of each pulse. Electrodes are placed at specific sites on the body for treatment of pain. TENS stimulates sensory nerves to block pain signals, stimulate endorphin production to help normalize sympathetic function.
Common uses: Acute and chronic pain, back and cervical muscular and disc syndromes, RSD, arthritis, shoulder syndromes, neuropathies, and many other painful conditions.
Electronic Muscle Stimulator ( EMS)
EMS is the acronym for "Electrical Muscle Stimulation". The low voltage electrical currents of EMS are adjusted to stimulate muscle motor nerve strands at a high enough intensity to cause muscle contractions and thus affect muscles at a deep level. EMS differs from TENS in that it is designed to stimulate muscle motor nerves, while TENS is designed to stimulate sensory nerve endings to help decrease pain.
Contraction/relaxation of muscles has been found to effectively treat a variety of musculoskeletal and vascular conditions. Benefits can include muscle relaxation, increased local blood circulation, and treatment of tenderness. Other common uses for EMS: increasing range of motion: preventing Muscle Disuse Atrophy, releasing muscle spasms, various conditions that benefit from increased local circulation.
Some of the uses of EMS are as follows:
Maintaining and Increasing range of motion: In conditions where the reduction of physiological range of motion is due to or the result of fractures with consequent immobilization, operative intervention, or arthroscopy, in shoulders, knees, and backs.
The Prevention or Retardation of muscle Disuse Atrophy: Muscle disuse atrophy is a reduction 'in muscle contraction and size due to prolonged impairment or joint immobility from surgery, injury or disease. The use of electrical stimulation to contract the muscles builds and strengthens the muscles, assisting in prevention of disuse atrophy.
Relaxation of muscle Spasms: Muscle spasms and cramping often occur in areas of localized pain and tenderness. Stimulation is used to fatigue the "spastic" muscle.
Muscle Reeducation: Evidence has shown that a combination of both exercise and electrical stimulation is far superior in strengthening atrophied muscles.
Local Blood Circulation: Rhythmic muscle contraction helps temporarily stimulate circulation, thereby aiding in the reduction of localized swelling and tenderness.
Immediate Post-surgical Stimulation of Calf Muscles to Prevent Venous Thrombosis: The use of EMS to temporarily stimulate circulation assists in the prevention of venous thrombosis.
Interferential Stimulator (IF)
Interferential current (IF) therapy, or interferential stimulation, is a more complex development of TENS, and is a unique way of effectively delivering therapeutic frequencies to tissue.
While conventional TENS devices deliver electrical pulses at extremely low frequency (typically 2-150 Hz), Interferential stimulation uses medium frequencies -- above 1000 Hz, and typically around 4000 Hz. Medium frequencies travel in the tissue much more easily, can go further and deeper, and with less discomfort to the patient.
Interferential is so named because "interference" between currents of multiple frequencies is what makes interferential devices effective. The "interference" occurs between the 2 or more currents used. One current has fixed frequency (typically at 4000 Hz) and the other's frequency varies by up to 400 Hz . At the point of intersection between the electrodes, which can be deeper than in TENS due to medium current's ease of penetration, the combined currents produce an "interference frequency", also called a "beat". That is a TENS-like low frequency, for example 100 Hz, and for body tissue it has a similar pain-relieving effect to TENS. As well as greater depth, interferential also allows an increased dosage because of the body tissue's better tolerance of medium-frequency currents. By using four electrodes Interferential treatment (IF) allows better focus and even deeper tissue stimulation. A more detailed discussion of Interferential follows.
Conventional TENS and Neuromuscular stimulators use discrete electrical pulses delivered at low frequencies of 2-160 Hz per second. However, Interferential stimulators use a fixed carrier frequency of 4,000 Hz per second and also a second adjustable frequency of 4,001-4,400 Hz per second. When the fixed and adjustable frequencies combine (heterodyne), they produce the desired signal frequency (Interference frequency, or beat). Interferential stimulation is concentrated at the point of intersection between the electrodes. This concentration occurs deep in the tissues as well as at the surface of the skin. Conventional TENS and Neuromuscular stimulators deliver most of the stimulation directly under the electrodes. Thus, with Interferential Stimulators, current perfuses to greater depths and over a larger volume of tissue than other forms of electrical therapy. When current is applied to the skin, capacitive skin resistance decreases as pulse frequency increases.' For example, at a frequency of 4,000 Hz (Interferential unit) capacitive skin resistance is eighty (80) times lower than with a frequency of 50 Hz (in the TENS range). Thus, Interferential current crosses the skin with greater ease and with less stimulation of cutaneous nociceptors allowing greater patient comfort during electrical stimulation. In addition, because medium-frequency (Interferential) current is tolerated better by the skin, the dosage can be increased, thus improving the ability of the Interferential current to permeate tissues and allowing easier access to deep structures. This explains why Interferential current may be most suitable for treating patients with deep pain, for promoting osteogenesis in delayed and nonunion fractures and in pseudothrosis, for stimulating deep skeletal muscle to augment the muscle pump mechanism in venous insufficiency, and for depressing the activity of certain cervical and lumbosacral sympathetic ganglia in patients with increased arterial constrictor tone. increased circulation.
Common uses: Pre and post-orthopedic surgery, joint injury syndrome, cumulative trauma disorders, increasing circulation and pain control of various origins.
High Voltage Pulsed Galvanic Stimulator (HVPGS)
"Galvanic" is often said to mean Unidirectional (Direct) current or DC, but it is more specifically a constant or unvarying DC that defines Galvanic. Unlike TENS and related treatments, Galvanic uses constant direct current (DC). Galvanic stimulation is a method of applying high voltage, but overall low amperage, direct current to alleviate pain, stimulate blood flow, and promote wound healing. Frequently used for injuries that are associated with bleeding or swelling, it is known by a number of other names including HVG (High Voltage Galvanic), HVGS (High Voltage Galvanic Stimulation), HVPGS (High Voltage Pulsed Galvanic Stimulation), HVS (High Voltage Stimulation), and DC (Direct Current Stimulation).
Galvanic stimulation combines very short pulse duration (of constant intensity) and high peak voltage, yet low total current per second, to give relative comfort and avoid tissue damage while stimulating deep tissues. It is also an efficient means of exciting nerve fibers.
With its constant unidirectional current flow, High Voltage Galvanic's oppositely-charged electrode pads set up a reaction that calls to mind hot and cold packs for injuries. The positive pad is like ice, tending to reduce circulation to the area under the pad and reduction in swelling. The negative pad is like heat, promoting increased circulation, reportedly speeding healing.
High-voltage pulsed galvanic stimulation (HVPGS) is gaining widespread use for wound healing, edema reduction and pain relief. Carpal Tunnel Syndrome and Diabetic Foot are two major areas of use. Devices in this class are characterized by a unique twin-peak monophasic waveform with very short pulse duration (microseconds) and a therapeutic voltage greater than 100 volts. The combination of very short pulse duration and high peak current, yet low total current per second (Microcurrent) allows relatively comfortable stimulation. Furthermore, this combination provides an efficient means of exciting sensory, motor and pain-conducting nerve fibers. Perceptual discrimination of those responses is relatively easy to achieve and thus its clinical versatility.
Microcurrent Stimulator (MC) or Microcurrent Electrical Neuromuscular Stimulator (MENS)
Microcurrent Therapy uses extremely tiny electrical currents (amounts of electricity measured in millionths of an ampere, or micro amps, symbolized as µA ) to help relieve pain and heal soft tissues of the body. The "microcurrent" designation distinguishes it from regular TENS therapy, which uses currents measured in mA (or milliamps). Typically TENS devices deliver currents up to 80 mA, but the limit for microcurrents is about 8 mA, equivalent to 8000 µA (or micro amps). Microcurrent units may operate well below that, at about 900 µA. Current levels that seem to be most effective in helping tissue heal range from 20 to 500 MicroAmps.
Microcurrent is used for the relief of pain, because of its close proximity to our own body's current, and is thought to work on a more cellular level.
It is theorized that healthy tissue exists within the direct flow of electrical current throughout our body. Electrical balance is disrupted when the body is injured at a particular site, causing the electrical current to change course. The use of Microcurrent over the injured site is thought to realign this flow and thus aid in tissue repair.
It has been found that ATP (Adenosine Triphosphate) in the cell helps promote protein synthesis and healing. The lack of ATP due to trauma of the tissue results in the decreased production of sodium and an increase in metabolic wastes, which is perceived as pain. It is theorized that the use of Microcurrent at an injured area helps realign the body's electrical current, increase the production of ATP, resulting in increased healing and recovery, as well as blocking the pain that is perceived.
Other devices may incorporate the above kinds of electrotherapy, for instance: Acupunctoscopes or Electroacupuncture devices, used in the Traditional Chinese Medicinal practice of acupuncture, which may have TENS functioning; as well as various skin beauty or facial-massaging devices and "wellness" or "biofeedback" devices (where the device is also capable of reading microcurrents in determining the amount of of microcurrents to apply to the body).