Effects of deep brain stimulation on prepulse inhibition in obsessive-compulsive disorder.

Owing to a high response rate, deep brain stimulation (DBS) of the ventral striatal area has been approved for treatment-refractory obsessive-compulsive disorder (tr-OCD). Many basic issues regarding DBS for tr-OCD are still not understood, in particular, the mechanisms of action and the origin of side effects. We measured prepulse inhibition (PPI) in treatment-refractory OCD patients undergoing DBS of the nucleus accumbens (NAcc) and matched controls. As PPI has been used in animal DBS studies, it is highly suitable for translational research. Eight patients receiving DBS, eight patients with pharmacological treatment and eight age-matched healthy controls participated in our study. PPI was measured twice in the DBS group: one session with the stimulator switched on and one session with the stimulator switched off. OCD patients in the pharmacologic group took part in a single session. Controls were tested twice, to ensure stability of data. Statistical analysis revealed significant differences between controls and (1) patients with pharmacological treatment and (2) OCD DBS patients when the stimulation was switched off. Switching the stimulator on led to an increase in PPI at a stimulus-onset asynchrony of 200 ms. There was no significant difference in PPI between OCD patients being stimulated and the control group. This study shows that NAcc-DBS leads to an increase in PPI in tr-OCD patients towards a level seen in healthy controls. Assuming that PPI impairments partially reflect the neurobiological substrates of OCD, our results show that DBS of the NAcc may improve sensorimotor gating via correction of dysfunctional neural substrates. Bearing in mind that PPI is based on a complex and multilayered network, our data confirm that DBS most likely takes effect via network modulation.

Management and outcome of pallidal deep brain stimulation in severe Huntington's disease.

Neurodegenerative movement disorders, such as Huntington's disease (HD), have become a promising field for Deep Brain Stimulation (DBS). This study aims to contribute to the establishment of a well-grounded database including both expected and unexpected effects of pallidal DBS in HD, and to discuss the ethical and legal restrictions of DBS in cognitively limited patients. Evaluation of the outcome data indicates that pallidal DBS exerted an independent effect on motor symptoms but probably also on the patient's cognitive and affective state. The cognitive decline, however, that characterizes the late stage of neurodegenerative disorders implicates ethical and legal problems given the patients' inability to give informed consent to DBS.

[Deep brain stimulation for psychiatric disorders: historical basis]. / Die tiefe Hirnstimulation bei psychiatrischen Erkrankungen : Historische Grundlagen.

Deep brain stimulation (DBS), which is already established as an effective treatment for movement disorders, such as Parkinson's disease, is increasingly being considered as a therapy option for mental diseases. Due to the increasing number of successful applications of DBS for otherwise therapy-resistant psychiatric diseases, DBS is becoming more and more of interest in fields of fundamental research as well as clinical care. However, the stimulation system is a medical product which has to be neurosurgically implanted and this fact is often used to draw certain analogies to earlier psychosurgical approaches in the era of Freeman. But, looking at the historical development of DBS, as is the aim of the present systematic and literature-based overview, it becomes obvious that DBS did not arise exclusively from the inglorious period of psychosurgery. In fact, two partly in parallel evolving lines of medical progress have contributed to the development of DBS as it is applied today. One of these lines is the use of lesional neurosurgical procedures, such as incision of capsules and cingulotomy, which in contrast to psychosurgical interventions in the era of Freeman, is aimed at subcortical structures and provides important basic knowledge for the choice of target points. In addition DBS is rooted in the application of an electrical charge with the goal to stimulate neuronal networks.

Clinical effectiveness of unilateral deep brain stimulation in Tourette syndrome.

Dysfunctional basal ganglia loops are thought to underlie the clinical picture of Tourette syndrome (TS). By altering dopaminergic activity in the affected neural structures, bilateral deep brain stimulation is assumed to have a modulatory effect on dopamine transmission resulting in an amelioration of tics. While the majority of published case reports deals with the application of bilateral stimulation, the present study aims at informing about the high effectiveness of unilateral stimulation of pallidal and nigral thalamic territories in TS. Potential implications and gains of the unilateral approach are discussed.