Deep brain stimulation for movement disorders

Abstract

Deep brain stimulation (DBS) is an implanted electrical device that modulates specific targets in the brain resulting in symptomatic improvement in a particular neurologic disease, most commonly a movement disorder. It is preferred over previously used lesioning procedures due to its reversibility, adjustability, and ability to be used bilaterally with a good safety profile. Risks of DBS include intracranial bleeding, infection, malposition, and hardware issues, such migration, disconnection, or malfunction, but the risk of each of these complications is low--generally ≤ 5% at experienced, large-volume centers. It has been used widely in essential tremor, Parkinson's disease, and dystonia when medical treatment becomes ineffective, intolerable owing to side effects, or causes motor complications. Brain targets implanted include the thalamus (most commonly for essential tremor), subthalamic nucleus (most commonly for Parkinson's disease), and globus pallidus (Parkinson's disease and dystonia), although new targets are currently being explored. Future developments include brain electrodes that can steer current directionally and systems capable of "closed loop" stimulation, with systems that can record and interpret regional brain activity and modify stimulation parameters in a clinically meaningful way. New, image-guided implantation techniques may have advantages over traditional DBS surgery.

Fig. 1

Composite X-rays showing an implanted deep brain stimulation system. The brain leads have 4 circumferential stimulating surfaces (contacts) located at their distal end. In this example, the leads are connected to bilateral single channel pulse generators in the chest; alternatively, both leads could be connected to a larger, 2-channel pulse generator located on either side

Fig. 2

(Top) Stereotactic deep brain stimulation (DBS) implantation in an awake patient with essential tremor. The DBS lead has been placed into the right thalamus, and the patient is being asked to trace a spiral on a clipboard. (Bottom) The ability of the patient to perform this task is compared with stimulation off and stimulation on, and the result is used, in part, to determine intraoperatively if the lead is appropriately placed in the thalamus

Fig. 3

Interventional magnetic resonance imaging (MRI) deep brain stimulation lead placement. (Left) A custom drape is used to create a sterile field in a standard 1.5-T scanner located in radiology. The entire procedure is performed in the MRI scanner with a plastic skull mounted aiming device and MRI compatible instrumentation. (Above right) The subthalamic nucleus is targeted using direct visualization of the nucleus on T2-weighted MRI images. (Below right) Real-time imaging is used to monitor insertion; in this case, the globus pallidus (GPi) is being implanted