Neuromodulation is "the alteration of nerve activity through targeted delivery of a stimulus, such as electrical stimulation or chemical agents, to specific neurological sites in the body".
[6] Technical improvements include a trend toward minimally invasive (or noninvasive) systems; as well as smaller, more sophisticated devices that may have automated feedback control,[7] and conditional compatibility with magnetic resonance imaging.
[16] Recent reviews highlight how neuromodulation is increasingly utilized across multiple medical subspecialties, providing clinicians with novel therapeutic options for both painful and non-painful complex disorders.
In general, neuromodulation systems deliver electrical currents and typically consist of the following components: An epidural, subdural or parenchymal electrode placed via minimally invasive needle techniques (so-called percutaneous leads) or an open surgical exposure to the target (surgical "paddle" or "grid" electrodes), or stereotactic implants for the central nervous system, and an implanted pulse generator (IPG).
Patient selection is key, and candidates should pass rigorous psychological screening as well as a medical workup to assure that their pain syndrome is truly medication-resistant.
Another invasive neuromodulation treatment developed in the 1980s is deep brain stimulation, which may be used to help limit symptoms of movement disorder in Parkinson's disease, dystonia, or essential tremor.
[23] Deep brain stimulation was approved by the U.S. Food and Drug Administration in 1997 for essential tremor, in 2002 for Parkinson's disease, and received a humanitarian device exemption from the FDA in 2003 for motor symptoms of dystonia.
[33][34] Another significant challenge of non-invasive electrical and magnetic methods is to localize the effect of stimulation on specific neuronal networks that need to be treated.
Again, these methods involve excessive exposure to intense electrical and magnetic fields several times and even orders of magnitude higher than natural ones in the brain.
Egyptians weren’t the only Mediterranean culture to feature the catfish in their art; similar murals appeared in the Roman city of Pompeii some 3,000 years later, though 1,000 miles to the north.
While these murals don’t confirm whether the fish were used medically, ancient Egyptian writings on papyri from 4,700 years ago document their use in pain relief.
Later historians like Pliny and Plutarch also noted that Egyptians employed electric eels to treat joint pain, migraines, depression, and epilepsy.
Norm Shealy at Western Reserve Medical School, using a design adapted by Tom Mortimer, a graduate student at Case Institute of Technology, from cardiac nerve stimulators by Medtronic, Inc., where he had a professional acquaintance who shared the circuit diagram.
[16]: 13–16 [41][42] Despite the limited clinical experience in these decades, that era is remarkable for the demonstration of the role technology has in neuromodulation, and there are some case reports of deep brain stimulation for a variety of problems; real or perceived.
Delgado hinted at the power of neuromodulation with his implants in the bovine septal region and the ability of electrical stimulation to blunt or alter behavior.
Further attempts at this "behavioral modification" in humans were difficult and seldom reliable, and contributed to the overall lack of progress in central nervous system neuromodulation from that era.
In particular, the so-called DBS "zero" electrode, (consisting of a contact loop on its end) had an unacceptable failure rate and revisions were fraught with more risk than benefit.
A number of physicians who hoped to address hitherto intractable problems sought development of more specialized equipment; for instance, in the 1960s, Wall's colleague Bill Sweet recruited engineer Roger Avery to make an implantable peripheral nerve stimulator.
Shortly before his retirement in 1983, he submitted data requested by the FDA, which had begun to regulate medical devices following a 1977 meeting on the topic, regarding DBS for chronic pain.
[16]: 13–16 [41][42] However, near this time in France and elsewhere, DBS was investigated as a substitute for lesioning of brain nuclei to control motor symptoms of movement disorders such as Parkinson's disease, and by the mid-1990s, this reversible, non-destructive stimulation therapy had become the primary application of DBS in appropriate patients, to slow progression of movement impairment from the disease and reduce side effects from long-term, escalating medication use.
Unlike preceding neuromodulation therapy methods, the approach would not involve electrical leads stimulating large nerves or spinal cords or brain centers.
Disease states and conditions that have been discussed as targets for future electroceutical therapy include diabetes, infertility, obesity, rheumatoid arthritis, and autoimmune disorders.