Deep Brain Stimulation in Treatment Resistant Schizophrenia

The purpose of this pilot study is to investigate the use of deep brain stimulation (DBS) of the substantia nigra pars reticulata (SNr) in subjects with treatment-resistant schizophrenia. There is a subset of patients with schizophrenia who continue to have persistent psychotic symptoms (auditory hallucinations and delusions) despite multiple adequate medication trials with antipsychotic medications including clozapine. There are currently no available treatments for such patients who generally have poor function and are chronically disabled, unable to work, live independently or have meaningful social relationships. Neuroimaging studies in patients with schizophrenia have revealed information about pathological neural circuits that could be suitable targets using deep brain stimulation. Although not yet tested in patients with schizophrenia, DBS is in early phase clinical trials in other psychiatric disorders. This pilot study will investigate the use of DBS in treatment-resistant schizophrenia subjects who have exhausted all other therapeutic alternatives but continue to have persistent disabling psychotic symptoms. Of note, DBS is not FDA approved for use in patients with schizophrenia. The method will be similar to that used in subthalamic nucleus stimulation in patients with Parkinson's Disease. However, the electrode will be advanced slightly inferior into the SNr, a major outflow nucleus of the basal ganglia, with the intention of causing local inhibition of SNr outflow resulting in disinhibition of the mediodorsal nucleus (MDN) of the thalamus. Hypofunction of the MDN has been implicated in the pathophysiology of schizophrenia in post-mortem as well as multiple structural and functional imaging studies. Evidence suggests that dysfunction of the MD is implicated in both positive and cognitive symptoms (such as working memory impairment) in schizophrenia. Frequent monitoring and clinical assessment with psychiatric scales will be used to monitor treatment response.