RESUMEN
INTRODUCTION: A novel neurostimulation system allows steering current in horizontal directions by combining segmented leads and multiple independent current control. The aim of this study was to evaluate directional DBS effects on parkinsonian motor features and adverse effects of subthalamic neurostimulation. METHODS: Seven PD patients implanted with the novel directional DBS system for bilateral subthalamic DBS underwent an extended monopolar review session during the first postoperative week, in which current thresholds were determined for rigidity control and stimulation-induced adverse effects using either directional or ring-mode settings. RESULTS: Effect or adverse effect thresholds were modified by directional settings for each of the 14 STN leads. Magnitude of change varied markedly between leads, as did orientation of optimal horizontal current steering. CONCLUSION: Directional current steering through chronically implanted segmented electrodes is feasible, alters adverse effect and efficacy thresholds in a highly individual manner, and expands the therapeutic window in a monopolar review as compared to ring-mode DBS. © 2016 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.
Asunto(s)
Estimulación Encefálica Profunda/efectos adversos , Estimulación Encefálica Profunda/instrumentación , Electrodos Implantados/normas , Enfermedad de Parkinson/terapia , Núcleo Subtalámico , Estimulación Encefálica Profunda/métodos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Proyectos PilotoRESUMEN
We explored the impact of pulse durations <60 µsec on the therapeutic window of subthalamic neurostimulation in Parkinson's disease. Current thresholds for full rigidity control and first muscle contractions were evaluated at pulse durations between 20 and 120 µsec during a monopolar review session in four patients. The average therapeutic window was 2.16 mA at 60 µsec, which proportionally increased by 182% at 30 µsec, while decreasing by 46% at 120 µsec. Measured chronaxies and model data suggest, that pulse durations <60 µsec lead to a focusing of the neurostimulation effect on smaller diameter axons close to the electrode while avoiding stimulation of distant pyramidal tract fibers.
RESUMEN
Schizophrenia has been suggested to be a neurodevelopmental disorder, and nitric-oxide-synthase (NOS)-positive neurons were shown to be involved in distorted cortical development in schizophrenia. Here we investigated whether nitrinergic neurons in the striatum of schizophrenic patients also display abnormalities regarding distribution or morphology. To do so, postmortem putaminal sections of schizophrenic subjects were examined by means of nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd) staining and NOS immunohistochemistry. NOS-positive neurons were counted and analyzed morphologically. Abnormalities regarding morphology or number of NOS-containing neurons could be found in the putamen of schizophrenics (n = 3), but not controls (n = 5). Neurons were either of abnormal size and branching pattern, or they were markedly reduced (130 +/- 44 vs. 54 +/- 62 NADPHd-positive somata/mm(3) putamen; p < 0.0001). Striatal nitrinergic interneurons might thus be involved in the pathogenesis of at least some forms of schizophrenia. Studies on larger samples are however needed to further corroborate this finding.
Asunto(s)
Interneuronas/enzimología , Interneuronas/patología , Neostriado/enzimología , Neostriado/patología , Óxido Nítrico Sintasa/metabolismo , Esquizofrenia/patología , Adulto , Anciano , Anciano de 80 o más Años , Recuento de Células , Colorantes , Femenino , Humanos , Inmunohistoquímica , Masculino , Persona de Mediana Edad , NADPH Deshidrogenasa/metabolismo , Óxido Nítrico Sintasa de Tipo IIRESUMEN
Neurons in the human striatum have been divided into five or seven different types, respectively. To further characterize these interneurons, we investigated the putamen of five brains by means of NADPH-diaphorase staining and compared our results to previous classifications in man. The NADPH-diaphorase method is selective for nitric oxide synthase (NOS); in the human striatum, predominantly interneurons were stained. NADPH-diaphorase positive neurons were then further examined. They showed clear morphological differences and could be classified into 12 different types, which only partially corresponded to previously described neuron types. Thus, we suggest at least three novel types of neostriatal interneurons. Furthermore, a special class of large neurons thought to be efferent in nature, stained NOS-positive.