Electroanalgesia is a form of

analgesia Pain management is an aspect of medicine and health care involving relief of pain (pain relief, analgesia, pain control) in various dimensions, from acute and simple to chronic and challenging. Most physicians and other health professional ...

, or pain relief, that uses

electricity Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as describe ...

to ease

pain Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, ...

. Electrical devices can be internal or external, at the site of pain (local) or delocalized throughout the whole body. It works by interfering with the electric currents of pain signals, inhibiting them from reaching the

brain A brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as Visual perception, vision. I ...

and inducing a response; different from traditional analgesics, such as

opiates An opiate, in classical pharmacology, is a substance derived from opium. In more modern usage, the term ''opioid'' is used to designate all substances, both natural and synthetic, that bind to opioid receptors in the brain (including antagonist ...

which mimic natural endorphins and

NSAID Non-steroidal anti-inflammatory drugs (NSAID) are members of a therapeutic drug class which reduces pain, decreases inflammation, decreases fever, and prevents blood clots. Side effects depend on the specific drug, its dose and duration of ...

s (non-steroidal anti-inflammatory drugs) that help relieve inflammation and stop pain at the source. Electroanalgesia has a lower addictive potential and poses less health threats to the general public, but can cause serious health problems, even death, in people with other electrical devices such as

pacemakers An artificial cardiac pacemaker (or artificial pacemaker, so as not to be confused with the natural cardiac pacemaker) or pacemaker is a medical device that generates electrical impulses delivered by electrodes to the chambers of the heart eit ...

or internal hearing aids, or with

heart problems Cardiovascular disease (CVD) is a class of diseases that involve the heart or blood vessels. CVD includes coronary artery diseases (CAD) such as angina and myocardial infarction (commonly known as a heart attack). Other CVDs include stroke, hea ...

History

The first cases of electroanalgesia were documented by Greek scholars,

Plutarch Plutarch (; grc-gre, Πλούταρχος, ''Ploútarchos''; ; – after AD 119) was a Greek Middle Platonist philosopher, historian, biographer, essayist, and priest at the Temple of Apollo in Delphi. He is known primarily for hi ...

and

Socrates Socrates (; ; –399 BC) was a Greek philosopher from Athens who is credited as the founder of Western philosophy and among the first moral philosophers of the ethical tradition of thought. An enigmatic figure, Socrates authored no t ...

, who noticed numbing effects of standing in pools of water on a beach that contained

electric fish An electric fish is any fish that can generate electric fields. Most electric fish are also electroreceptive, meaning that they can sense electric fields. The only exception is the stargazer family. Electric fish, although a small minority, inc ...

.[Jensen, Jack E., Richard R. Conn, Gary Hazelrigg, and John E. Hewett. "The Use of Transcutaneous Neural Stimulation and Isokinetic Testing in Arthroscopic Knee Surgery." The American Journal of Sports Medicine 13 (1985): 27-33]. The Chinese practice of acupuncture, dating back to 3000 BCE, also utilizes the properties of electroanalgesia by stimulating specific nerves to produce electrical signals which produce pleasurable responses in the brain. Another ancient analgesic method, aging back to 5000 BCE in

Sumer Sumer () is the earliest known civilization in the historical region of southern Mesopotamia (south-central Iraq), emerging during the Chalcolithic and early Bronze Ages between the sixth and fifth millennium BC. It is one of the cradles of ...

, is to use natural minerals,

vitamin A vitamin is an organic molecule (or a set of molecules closely related chemically, i.e. vitamers) that is an essential micronutrient that an organism needs in small quantities for the proper functioning of its metabolism. Essential nutrie ...

s, and

herbs In general use, herbs are a widely distributed and widespread group of plants, excluding vegetables and other plants consumed for macronutrients, with savory or aromatic properties that are used for flavoring and garnishing food, for medicina ...

, usually in a mixture with other natural products. Technology invented specifically for electroanalgesia emerged at the beginning of the 1900s.

Technology

Advancements in technology within the past fifteen years have created multiple forms of electroanalgesia. Doctors can target specific electrical signals caused by pain and cancel them out using electrical signals, optimally with alternating low and high

frequencies Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from ''angular frequency''. Frequency is measured in hertz (Hz) which is e ...

Transcranial electrostimulation

A theoretical explanation for the mechanism of pain reduction by transcranial electrostimulation, or TCES, suggests that the electrical stimulation activates the anti-nociceptive system in the brain, resulting in β-endorphin,

serotonin Serotonin () or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter. Its biological function is complex and multifaceted, modulating mood, cognition, reward, learning, memory, and numerous physiological processes such as vomiting and va ...

and

noradrenaline Norepinephrine (NE), also called noradrenaline (NA) or noradrenalin, is an organic chemical in the catecholamine family that functions in the brain and body as both a hormone and neurotransmitter. The name "noradrenaline" (from Latin '' ad'', ...

release. abis L, Shklar B, Geva D: Immediate influence of transcranial electrostimulation on pain and β-endorphin blood levels: An active placebo-controlled study. Am J Phys Med Rehabil 2003;82:81-85. TCES can be used on people with cervical pain, chronic lower back syndrome, or migraines. It cannot be used on people with orthopedic or radiological potentially serious spinal conditions,

hydrocephalus Hydrocephalus is a condition in which an accumulation of cerebrospinal fluid (CSF) occurs within the brain. This typically causes increased pressure inside the skull. Older people may have headaches, double vision, poor balance, urinary i ...

epilepsy Epilepsy is a group of non-communicable neurological disorders characterized by recurrent epileptic seizures. Epileptic seizures can vary from brief and nearly undetectable periods to long periods of vigorous shaking due to abnormal electrica ...

glaucoma Glaucoma is a group of eye diseases that result in damage to the optic nerve (or retina) and cause vision loss. The most common type is open-angle (wide angle, chronic simple) glaucoma, in which the drainage angle for aqueous humor, fluid withi ...

malignant hypertension A hypertensive emergency is very high blood pressure with potentially life-threatening symptoms and signs of acute damage to one or more organ systems (especially brain, eyes, heart, aorta, or kidneys). It is different from a hypertensive urgency ...

pacemaker An artificial cardiac pacemaker (or artificial pacemaker, so as not to be confused with the natural cardiac pacemaker) or pacemaker is a medical device that generates electrical impulses delivered by electrodes to the chambers of the heart ei ...

or other implanted electronic device; recent

cerebral trauma A traumatic brain injury (TBI), also known as an intracranial injury, is an injury to the brain caused by an external force. TBI can be classified based on severity (ranging from mild traumatic brain injury TBI/concussionto severe traumatic ...

nervous system In biology, the nervous system is the highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body. The nervous system detects environmental changes ...

infection, skin

lesions A lesion is any damage or abnormal change in the tissue of an organism, usually caused by disease or trauma. ''Lesion'' is derived from the Latin "injury". Lesions may occur in plants as well as animals. Types There is no designated classifi ...

at sites of electrode placement; oncological disease; patients undergoing any other treatments for pain; any invasive therapy, e.g. surgery, within the last month. The equipment used is Pulse Mazor Instruments' Pulsatilla 1000, which consists of a headset with three

electrode An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). Electrodes are essential parts of batteries that can consist of a variety of materials ...

s, two that go behind the ears and one that goes on the forehead, that release set frequencies of electricity at set intervals.

Deep brain stimulation

Deep brain stimulation Deep brain stimulation (DBS) is a neurosurgical procedure involving the placement of a medical device called a neurostimulator, which sends electrical impulses, through implanted electrodes, to specific targets in the brain (the brain nucleus ...

, or DBS, was first evaluated as an electroanalgesic in the late 1950s. It works in some chronic pain patients. The mechanism of DBS is unknown. There is some evidence that it decreases pain transmission along sensory discriminative pathways although more recent studies have shown that it has central effects on other brain regions involved in the pain network (Pereira et al. 2007). This method has mainly been used for chronic pain patients after all other options have failed due to potential of intracranial complications (e.g.,

intracranial hemorrhage Intracranial hemorrhage (ICH), also known as intracranial bleed, is bleeding within the skull. Subtypes are intracerebral bleeds (intraventricular bleeds and intraparenchymal bleeds), subarachnoid bleeds, epidural bleeds, and subdural blee ...

, infection, and oculomotor abnormalities). An electrode is "stereotactically" guided to the site using

magnetic resonance imaging Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio wave ...

and once in place, the electrode is activated by subcutaneous leads attached to a pulse generator under the skin. It is effective in treating refractory post-stroke pain, atypical face pain, anaesthesia dolorosa, and deafferentation and somatic pain such as in phantom limb or brachial plexus injury (Boccard et al. 2013).

Peripheral nerve stimulation

The use of peripheral nerve stimulation, or PNS, for the relief of chronic pain states was first reported over 30 years ago. Recent studies have demonstrated that electrical stimulation of

nerve A nerve is an enclosed, cable-like bundle of nerve fibers (called axons) in the peripheral nervous system. A nerve transmits electrical impulses. It is the basic unit of the peripheral nervous system. A nerve provides a common pathway for the ...

s leads to inhibitory input to the pain pathways at the

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the sp ...

level. PNS is most effective in the treatment of neuropathic pain (e.g., posttraumatic neuropathy, diabetic neuropathy) when the nerve lesion is distal to the site of stimulation. hite, Paul F., Shitong Li, and Jen W. Chiu. "Electroanalgeia: Its Role in Acute and Chronic Pain Management." Anestesia and Analgesia 92 (2001): 505-13.

Percutaneous electrical nerve stimulation

Percutaneous electrical nerve stimulation, or PENS, is used mainly in the treatment of intractable pain associated with chronic low back pain syndrome, cancer, and other disorders. It is a technique involving insertion of an ultra-fine acupuncture needle which probes into the

soft tissue Soft tissue is all the tissue in the body that is not hardened by the processes of ossification or calcification such as bones and teeth. Soft tissue connects, surrounds or supports internal organs and bones, and includes muscle, tendons, ...

s or

muscle Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of mus ...

s to electrically stimulate nerve fibers in the sclerotomal, myotomal, or dermatomal distribution corresponding to the patient's pain symptoms. PENS is related to both

electroacupuncture Electroacupuncture is a form of acupuncture where a small electric current is passed between pairs of acupuncture needles. According to some acupuncturists, this practice augments the use of regular acupuncture, can restore health and well-bei ...

and

transcutaneous electrical nerve stimulation Transcutaneous electrical nerve stimulation (TENS or TNS) is the use of electric current produced by a device to stimulate the nerves for therapeutic purposes. TENS, by definition, covers the complete range of transcutaneously applied currents ...

Percutaneous neuromodulation therapy

PENS used to be a term to describe a neurosurgical procedure involving implantation of temporary stimulating electrodes before an SCS device. The term has recently been changed to percutaneous

neuromodulation Neuromodulation is the physiological process by which a given neuron uses one or more chemicals to regulate diverse populations of neurons. Neuromodulators typically bind to metabotropic, G-protein coupled receptors (GPCRs) to initiate a second ...

therapy, or PNT. The term PNT was chosen because it more accurately describes the neurophysiologic basis for PENS-induced analgesia.

Transcutaneous electrical nerve stimulation

Transcutaneous electrical nerve stimulation, or TENS, involves the transmission of electrical energy from an external stimulator to the peripheral nervous system via cutaneously placed conductive gel pads. TENS can be subclassified into two variants: * low-intensity (1–2 mA), high-frequency (50–100 Hz) TENS; and * acupuncture-like high-intensity (15–20 mA), low-frequency (1–5 Hz) or "dense-disperse" TENS. The purported mechanism of action of TENS invokes both spinal supraspinal theories.

Transcutaneous acupoint electrical stimulation

Transcutaneous acupoint electrical stimulation, or TAES, is a variant of TENS therapy that involves applying cutaneous electrodes at classical Chinese

acupoint Acupuncture is a form of alternative medicine and a component of traditional Chinese medicine (TCM) in which thin needles are inserted into the body. Acupuncture is a pseudoscience; the theories and practices of TCM are not based on Science, ...

s and stimulating with alternating high- and low-frequency electric current (" dense-disperse"). Acupoint stimulation is as effective as dermatomal stimulation in producing an analgesic-sparing effect after lower abdominal surgery

H-wave therapy

H-wave therapy (HWT) is a form of electrical stimulation that produces a direct, localized effect on the conduction of underlying nerves. The electrical stimulation used in HWT differs from other forms of electrical stimulation such as TENS in terms of its

waveform In electronics, acoustics, and related fields, the waveform of a signal is the shape of its graph as a function of time, independent of its time and magnitude scales and of any displacement in time.David Crecraft, David Gorham, ''Electro ...

; it is intended to emulate the H waveform found in nerve signals, thus permitting the machine to use less power while attaining greater and deeper penetration of its low-frequency current. The waves used in HWT are distinct from the H-waves that are part of

electromyography Electromyography (EMG) is a technique for evaluating and recording the electrical activity produced by skeletal muscles. EMG is performed using an instrument called an electromyograph to produce a record called an electromyogram. An electromyo ...

. It has been used in the treatment of pain related to

diabetic neuropathy Diabetic neuropathy is various types of nerve damage associated with diabetes mellitus. Symptoms depend on the site of nerve damage and can include motor changes such as weakness; sensory symptoms such as numbness, tingling, or pain; or autonomic c ...

, muscle

sprain A sprain, also known as a torn ligament, is an acute soft tissue injury of the ligaments within a joint, often caused by a sudden movement abruptly forcing the joint to exceed its functional range of motion. Ligaments are tough, inelastic fiber ...

s, temporomandibular joint disorders, type I

complex regional pain syndrome Complex regional pain syndrome (CRPS) is any of several painful conditions that are characterized by a continuing (spontaneous and/or evoked) regional pain that is seemingly disproportionate in time or degree to the usual course of any known trau ...

as well as the healing of wounds such as diabetic ulcers. This electroanalgesic modality was originally recommended as an alternative to TENS for dental analgesia. In a 1999

randomized controlled trial A randomized controlled trial (or randomized control trial; RCT) is a form of scientific experiment used to control factors not under direct experimental control. Examples of RCTs are clinical trials that compare the effects of drugs, surgical t ...

involving a mechanical pain model, the analgesic effects of HWT were found to be short-lasting and identical to those provided by TENS therapy. HWT has not been shown effective in reducing pain in cases other than diabetic neuropathy, nor has it been shown effective in reducing edema or swelling, and it has specifically not been shown effective in treating

chronic pain Chronic pain is classified as pain that lasts longer than three to six months. In medicine, the distinction between acute and chronic pain is sometimes determined by the amount of time since onset. Two commonly used markers are pain that continue ...

due to

ischemia Ischemia or ischaemia is a restriction in blood supply to any tissue, muscle group, or organ of the body, causing a shortage of oxygen that is needed for cellular metabolism (to keep tissue alive). Ischemia is generally caused by problems w ...

Interferential current therapy

Interferential current therapy, or ICT, is another variant of TENS that uses the principle of

amplitude modulation Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave. In amplitude modulation, the amplitude (signal strength) of the wave is varied in proportion to ...

to decrease the discomfort of stimulating deeper tissues (e.g., muscle) when using transcutaneously applied electric current. A combination of different stimulation frequencies are used (i.e., one fixed at 4 kHz and another within a variable range) to generate frequencies between 4 and 250 Hz which are alleged to more effectively penetrate the soft tissues while producing less discomfort at the skin surface. With ICT, its postulated mechanism of analgesic action is through direct stimulation of muscle fibers rather than nerves, allegedly improving muscle blood flow and promoting the healing process. Although ICT is used widely in the

physiotherapy Physical therapy (PT), also known as physiotherapy, is one of the allied health professions. It is provided by physical therapists who promote, maintain, or restore health through physical examination, diagnosis, management, prognosis, patie ...

and rehabilitative medicine settings, there is a dearth of rigorously controlled studies to justify its effectiveness in the management of either acute or chronic pain syndromes.

Piezo-electric current therapy

Piezo-electric current therapy, or PECT, is an analgesic technique based on the principle that mechanical deformation of a motorized

piezoelectric Piezoelectricity (, ) is the electric charge that accumulates in certain solid materials—such as crystals, certain ceramics, and biological matter such as bone, DNA, and various proteins—in response to applied mechanical stress. The word '' ...

ceramic A ceramic is any of the various hard, brittle, heat-resistant and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcelain, ...

rod produces a burst of 10 electrical pulses (five positive and five negative), each lasting 2–3 ms. Each electrical burst lasts for 50 to 250 ms (depending on the motor speed set) and generates a current of approximately 25 mA. The application of PECT to the skin for 2 min produces a tolerable "pricking" pain sensation associated with a neurogenic inflammatory response lasting 3–4 h. The extent and duration of this inhibitory process is directly related to the intensity of the applied stimulus and is alleged to be associated with the release of endogenous endorphins. iller JC, Le Bars D, De Broucker T. Diffuse noxious inhibitory control in man: involvement of an opioidergic link. Eur J Pharmacol 1990;182:347–55.

Controversies

Electroanalgesia poses serious health problems in those patients who need other electrical equipment in their bodies, such as

s and

hearing aid A hearing aid is a device designed to improve hearing by making sound audible to a person with hearing loss. Hearing aids are classified as medical devices in most countries, and regulated by the respective regulations. Small audio amplifiers s ...

s, because the electrical signals of the multiple devices can interfere with each other and fail. People with

heart The heart is a muscular Organ (biology), organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as ca ...

problems, such as

irregular heartbeat Arrhythmias, also known as cardiac arrhythmias, heart arrhythmias, or dysrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. A resting heart rate that is too fast – above 100 beats per minute in adults ...

, are also at risk because the devices can throw off the normal electrical signal of the heart.

References

{{Pain Analgesics Electrotherapy Medical treatments