Footnotes Conflict of interest: No potential conflict of interest relevant to this article was reported.
The medical field mostly relies on chemicals to treat illness, but since neurons use electrical signaling, electrical currents can alter their activity—a phenomenon increasingly exploited to treat neurological disorders. The first evidence for the use of electrical stimulation to treat chronic pain comes from antiquity, in the Compositiones Medicam entorum, the early guide to drugs and recipes written in 47 CE by Scribonius Largus, the court

physician of the Roman emperor check details Claudius.2 Inhibitors,research,lifescience,medical He described using electrical currents to treat headaches and gout by applying electric torpedo fish to the painful regions. Inhibitors,research,lifescience,medical This treatment was popular for seizures, depression, and pain until the eighteenth century. Electricity-based therapies later multiplied, based on the work of Luigi Galvani, Charles Le Roy, Duchenne de Boulogne, Beard and Rockwell, and others.3 Obviously, not all such treatments were well-grounded. Electrical stimulation was also applied to treat refractory chronic pain, with deep brain stimulation (DBS) as the first modern method. In DBS, small electrodes are surgically implanted in precise brain locations to deliver tiny electrical currents to neurons immediately adjacent to the electrode. Inhibitors,research,lifescience,medical Thus, unlike

with medications, there are no distant adverse effects (e.g. rashes, gastrointestinal upset, allergies). Since only nearby neurons are affected, most brain functions continue unperturbed. A battery is implanted subcutaneously to power the electrode using technology based on cardiac pacemakers. Inhibitors,research,lifescience,medical A 1960 Inhibitors,research,lifescience,medical article by Heath and Mickle reported that DBS applied to the septum between the lateral ventricles of the brain produced immediate pain relief in a series

of six patients with intractable pain, results duplicated by other early studies.4–6 In 1977, Richardson and Akil reported analgesic efficacy of DBS of the periaqueductal and periventricular gray matter.7,8 Stimulation of another deep target involved in pain sensation, the periventricular gray matter of the posterior Non-specific serine/threonine protein kinase thalamus, brought good pain relief to patients with cancer pain.9 Despite these encouraging results, high costs and rates of complication have limited DBS use; 3.9% of patients developed permanent neurological deficits, thalamic hemorrhage, or death, while 19.1% of patients had temporary complications, including neurological deficits, infection, and hardware malfunction.10 Epidural brain stimulation then emerged as a less invasive alternative. Here the electrodes are implanted under the skull, but outside the dura, so the brain itself is not disturbed and the risk is lower, although only superficial areas of the brain can be reached.