Deep brain stimulation. A type of neurosurgery used to treat people who have had Parkinson's usually for 10-15 years. When the stimulator is switched "on", electrical signals are sent to the brain to stop or reduce the Parkinson's symptoms. When the stimulator is switched "off" the symptoms return. It works by implanting an electrode in a specific part of the brain (the thalamus, the globus pallidus, or the subthalamic nucleus). This is then connected to a small unit called an implantable pulse generator (IPG) which is implanted under the skin in the chest, rather like a heart pacemaker. The IPG contains the battery and electronics to generate the electrical signals for the stimulation. The IPG is programmed by the clinician using a computer, but on a day-to-day basis the stimulation can be switched "on" and "off" by the person with Parkinson's using a hand-held programmer or a magnet. See the PDS information sheet Deep Brain Stimulation (FS17) - 569kb pdf format.