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Using electrical stimulation to manage brain disorders has a long and chequered history. Deep Brain Stimulation (DBS) is the latest. It involves implanting electrodes, connected to a computerized pulse generator, deep into the structure of the brain. DBS is increasingly used for managing a number of neuropsychiatric conditions.
The finding that DBS of the thalamus for chronic pain patients also improved tremor was a chance discovery that led to a landmark study in 2009 for Parkinson’s disease. The range of applications for DBS has grown since, fuelled by developments in imaging the connectivity of brain circuits.1 Revealing these functional networks allows the tracts activated by electrodes to be identified. Technical advances in electrodes, surgical technique and stimulus control allow increasingly sophisticated use.2
Parkinson’s disease is managed with medication in its early stages. Over time the beneficial effects lessen as disabling side-effects and non-motor problems become prominent. DBS is an invasive treatment mainly reserved for patients with advanced disease, but interest has developed in using DBS at a much earlier stage to maintain patients’ quality of life, work and social activity.3
In epilepsy about 30% of patients find they cannot manage symptoms adequately with medication, and even more experience limitations from side-effects. Surgery can remove epileptic foci but is not open for patients with widespread or bilateral foci. For them DBS could help. A number of sites can be targeted, depending on the epilepsy type, with benefits, such as fewer seizures and falls, improved cognition, reduced medication problems and better quality of life. As a result, mortality may be improved and the reduction in disability can be significant.4
Movement disorders, such as Huntington’s disease and Tourette syndrome, have been the focus of study, in addition to that most neurological of psychiatric disorders, Obsessive Compulsive Disorder. DBS has improved understanding of functional brain anatomy, leading to more studies on Alzheimer’s disease, treatment-resistant depression, addiction, post traumatic stress disorder, anorexia nervosa and obesity. While this research is promising, the results are far from being part of routine care. But increasingly cross-diagnostic studies in large populations are helping identify common core abnormalities that offer targets for using DBS in the future.5
Electrical stimulation of the brain for therapeutic effect is not limited to DBS. Electroconvulsive therapy (ECT) is well established if poorly focused; Transcranial Magnetic Stimulation (rTMS) and Transcranial Direct Current Stimulus (tDCS) offer alternative non-invasive technologies; whilst Epidural Cortical Stimulation (EpCS) is less invasive and useful for targets on the brain’s surface.6
DBS and related electrical interventions are on an upward curve, with improvements in techniques, technology and imaging techniques driving them forward. There will inevitably come a period of reassessment before they finally settle into their place in the routine management of these disorders and their full impact on mortality and disability can be assessed.
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