The first cases of electroanalgesia were documented by Greek scholars, Plutarch and Socrates, who noticed numbing effects of standing in pools of water on a beach that contained electric fish (icthyoelectroanalgesia).
[citation needed] 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 and noradrenaline release.
[3] It cannot be used on people with orthopedic or radiological potentially serious spinal conditions, hydrocephalus, epilepsy, glaucoma, malignant hypertension, pacemaker or other implanted electronic device; recent cerebral trauma, nervous system infection, skin lesions at sites of electrode placement; oncological disease; patients undergoing any other treatments for pain; any invasive therapy, e.g. surgery, within the last month.
[6] Recent studies have demonstrated that electrical stimulation of nerves leads to inhibitory input to the pain pathways at the spinal cord level.
[8] It is a technique involving insertion of an ultra-fine acupuncture needle which probes into the soft tissues or muscles to electrically stimulate nerve fibers in the sclerotomal, myotomal, or dermatomal distribution corresponding to the patient's pain symptoms.
[8] PENS used to be a term to describe a neurosurgical procedure involving implantation of temporary stimulating electrodes before an SCS device.
In a 1999 randomized controlled trial involving a mechanical pain model, the analgesic effects of HWT were found to be short-lasting and identical to those provided by TENS therapy.
Although ICT is used widely in the physiotherapy 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.
[8] Piezo-electric current therapy, or PECT, is an analgesic technique based on the principle that mechanical deformation of a motorized piezoelectric ceramic 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.[8] 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.