Deep Brain Stimulation: A New Era in Functional Neuroscience?

Abstract

Deep Brain Stimulation (DBS) evolved from functional stereotactic neurosurgery techniques designed to produce selective lesions of the thalamus and cerebellum [1]. In 1952, Irving S. Cooper discovered the potential of ligation therapy when he unintentionally occluded the anterior choroidal artery, causing a medial globuspallidal infarction, which, surprisingly, alleviated rest tremor, rigidity and contralateral cogwheeling. Throughout the 1950s and 1960s, techniques for ablative procedures were refined with much focus on identifying the ideal targets. The motor thalamus and globuspallidusinternus (GPi) were considered the most effective targets [ 2,3]. In the 1960s, L-dopa became the standard of care for Parkinson’s disease (PD) and the popularity of ablative surgeries significantly decreased. During this time, ablative surgeries were primarily limited to thalamotomy to treat tremor and pallidotomy and thalamotomy for dystonia; they were rarely done to treat PD. However, by the 1980s, the limitations (motor fluctuations and dyskinesias) of L-dopa became apparent and ablative surgeries for PD regained popularity [1,3]. Building on the experience of ablative surgeries, stimulation procedures started to become commonplace in the management of movement disorders by the 1990s. This introduced a new era in functional neuroscience for movement disorders. Over the last 20 years, DBS has become the surgical treatment of choice for movement disorders due to its superior safety profile over ablative procedures and the ability to adjust and potentially reverse the stimulation effects [3-5]. Since 1995, Medtronic reports over 80,000 individuals have been implanted stereotactically worldwide [6]. Despite its popularity, there is still controversy over the superiority of medical therapy versus DBS. Currently, PD and essential tremor (ET) are the only FDA approved indications for DBS, with dystonia and obsessive compulsive disorder being approved under a Humanitarian Device Exemption; however, many more neurological and psychiatric disorders are currently being studied [6,7]. While the advent of DBS has revolutionized the field of functional neuroscience, it is still very much in its infancy. Beyond the currently approved neurological indications, our group has shown DBS to have significant impact in tremor control for patients with the neurodegenerative disorder, Fragile X-associated Tremor Ataxia Syndrome (FXTAS), where patients initially present with intention tremor followed by gait ataxia [8]. As technologies continue to advance, functional neuroscience will not only be the future of clinical neurology but likely will have a stronghold as an accepted treatment alternative for disease processes such as depression, epilepsy, eating disorder, cluster headaches, chronic and phantom limb pain, Tourette’s syndrome, drug resistant hypertension and posttraumatic coma [3,9].