What the future holds for deep brain stimulation.

For 20 years, deep brain stimulation (DBS) at high frequency has been developed as a substitute for the classical lesioning methods previously used in stereotactic and functional neurosurgery. This method has proven its efficacy, based on its reversibility and adaptability: two factors that are responsible for low morbidity. The method has been initially developed for and applied to movement disorders in several target areas; such as the thalamus, the pallidum and the subthalamic nucleus. It has now also been extended to other indications, such as epilepsy, dystonias and cluster headache and, more recently, to psychiatric disorders, such as obsessive-compulsive disorder, Gilles de la Tourette tics and depression. Several other disorders are currently under investigation and these may become new indications in the future. The mechanism of action is likely to be complex; associating cell-firing inhibition, neurotransmitter depletion, jamming and excitation of inhibitory pathways that lead to functional inhibition, mimicking the effects of lesioning of the stimulated structures. High-frequency stimulation of the subthalamic nucleus induces neuroprotection in animal models but has not yet been demonstrated in human patients suffering from Parkinson's disease. Technological development will enhance and refine the effects of high-frequency stimulation, and allow further extension of this method to new targets and new indications.