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.

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Schizophrenia is a psychiatric disorder characterized by heterogeneous symptoms, affecting 0.8-1% of the population worldwide. It usually begins in early adulthood and demonstrates a chronic course. In recent years research interest has turned to the increased burden of somatic illness in schizophrenia, with special emphasis on metabolic syndrome and diabetes. In this article I review the theoretical and practical aspects of the comorbidity of schizophrenia with metabolic syndrome and diabetes mellitus. Epidemiological studies demonstrate the occurrence of metabolic syndrome between 22% and 66%, while the prevalence of diabetes is at least threefold compared to the non-psychiatric population in all age groups. Etiologically it is not clear to what extent these alterations are caused by direct genetic and biological effects in contrast to environmental factors. Among the latter the role of atypical antipsychotics should be emphasized. Clinical management of prediabetic conditions and diabetes in schizophrenia warrants the close cooperation of professionals working in the areas of psychiatry and diabetology. This cooperation should include close metabolic monitoring, lifestyle and dietary training, moreover careful modification and in some cases switching of antipsychotic medication. Persisting metabolic symptoms or diabetes require treatment with oral antidiabetics, fibrates, and statins.

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