Advances in Deep Brain Stimulation

Bioelectric medicine uses electrical stimulation to switch off chronic pain, as well as diagnose, monitor, and control inflammatory disease. Deep-brain stimulation has already been applied to patients with Parkinson's disease and holds the promise of treating such diseases as rheumatoid arthritis, lupus, diabetes, hepatitis, hypertension, bowel disease, and other chronic conditions.

The central focus of most of this research is the vagus nerve, which sends signals from the brain to the gastrointestinal tract, heart, liver, spleen, and other organs. Infection or injury creates a biochemical imbalance, the changes are relayed to motor neurons in the brain, which send back signals to the affected organ to regulate the chemicals that produce inflammatory reactions throughout the body. Bio-electric stimulation aims to control this immune response by shocking the circuits that control the immune system and thereby harness them to treat inflammatory diseases. Results so far suggest that this approach will help treat disorders such as rheumatoid arthritis, multiple sclerosis, and possibly even diabetes and cancer.

The development of new techniques to identify and control the nervous system's pathways responsible for inflammatory responses is proceeding rapidly. In 2011, vagus nerve stimulator was implanted just beneath the collarbone of a patient suffering from crippling rheumatoid arthritis. Within weeks, he was nearly pain-free and, four years after the surgery, remaining in total remission without steroids. In 2015, the U.S. Food and Drug Administration approved the use of a vagus nerve stimulator to treat obe-sity. The National Institutes of Health (NIH) funded the $250-million project Stimulating Peripheral Activity to Relieve Conditions (SPARC), and DARPA has launched Electrical Prescriptions (ElectRx) to advance bioelectric technology research. Inevitably, bioelectric medicine will replace or augment the drugs currently prescribed for the treatment of inflammatory diseases.

Bioelectric treatment has also been implemented successfully to treat severe depression. PET (Positron Emission Tomography) scans were used to map areas of the brain that exhibited marked changes during periods of depression, revealing increased blood flow in certain regions of the middle brain. Conversely, areas of the brain responsible for positive motivation exhibited decreased activity. The specific location of the brain responsible for depression was pinpointed in a small area called the subcallosal cingulate area, which functions as a hub for decision making, emotional responses, and memory retention.

This finding led to a revolutionary treatment, by surgically implanting electrodes close to the subcallosal cingulate to send an electrical current through the associated neural circuits.

Deep brain stimulation has been used since 2002 to treat Parkinson's Disease. The effectiveness of the technology has generated interest among researchers to apply the technique for other maladies such as bipolar disorder, obsessive-compulsive disorder, and Tourette's syndrome.