Browsing by Author "Menon, Bijoy"
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- ItemOpen AccessDevelopment of a Miniaturized Biphasic Constant-Current Charge-Balanced Stimulator for Freely Moving Animals(2016-02-03) Acosta Calvillo, Adan Isaac; Murari, Kartikeya; Vyas, Rushi; Menon, Bijoy; Rival, David; Nowicki, EdwinNeurological disorders are diseases that target the central and peripheral nervous system. These disorders include Alzheimer, Parkinson’s disease and other dementias. Common treatment for some neurological disorders are drugs and when this method is not so effective, the next method is electrical stimulation, where a Deep Brain Stimulation (DBS) device is surgically implanted. In spite of extensive application in humans and research in animals, the mechanisms of DBS remain unclear. This thesis presents a miniaturized discrete system for long-term, biphasic constant current, charge balanced stimulation for DBS research in small animals with independently programmable anodic and cathodic currents and pulse widths, frequency, pulse order and inter pulse interval. It features a single current source and an H-bridge for setting current direction. The system is highly customizable, permitting trade-off between voltage compliance and the range, resolution and accuracy of currents and between power consumption and temporal resolution with minimal hardware modification.
- ItemOpen AccessLeptomeningeal Collateral Status in Patients with Acute Ischemic Stroke: Determinants and Relationship with Clinical Outcome(2014-12-24) Menon, Bijoy; Hill, MichaelObjectives Identify determinants associated with variability in collateral status in patients with acute ischemic stroke and test if collateral status on CTA can be used to select patients for intra-arterial therapy (IAT). Methods Data are from the Keimyung Stroke Registry. Patients with M1 MCA occlusion on baseline CTA from 5/2004 to 7/2009 were included. All imaging was analyzed blinded to clinical information. Results Multivariable modeling identified metabolic syndrome (OR 3.22 95% CI 1.69-6.15, p<0.001), hyperuricemia (per 1 mg/dl OR 1.35 95% CI 1.12-1.62, p<0.01) and older age (per 10 years, OR 1.34 95% CI 1.02-1.77, p=0.03) as independent predictors of poor collateral status. Only patients with intermediate or good collaterals who recanalize show association with good clinical outcome. (Rate Ratio=3.8, 95% CI 1.2-12.1). Conclusions Metabolic syndrome, hyperuricemia and age are associated with poor collateral status. Patients with poor collaterals on CTA do not benefit from IAT.