Neurology
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Distal symmetric polyneuropathy (DSP) is the most common variety of neuropathy. Since the evaluation of this disorder is not standardized, the available literature was reviewed to provide evidence-based guidelines regarding the role of laboratory and genetic tests for the assessment of DSP. ⋯ 1) Screening laboratory tests may be considered for all patients with polyneuropathy (Level C). Those tests that provide the highest yield of abnormality are blood glucose, serum B12 with metabolites (methylmalonic acid with or without homocysteine), and serum protein immunofixation electrophoresis (Level C). If there is no definite evidence of diabetes mellitus by routine testing of blood glucose, testing for impaired glucose tolerance may be considered in distal symmetric sensory polyneuropathy (Level C). 2) Genetic testing should be conducted for the accurate diagnosis and classification of hereditary neuropathies (Level A). Genetic testing may be considered in patients with cryptogenic polyneuropathy who exhibit a hereditary neuropathy phenotype (Level C). Initial genetic testing should be guided by the clinical phenotype, inheritance pattern, and electrodiagnostic features and should focus on the most common abnormalities which are CMT1A duplication/HNPP deletion, Cx32 (GJB1), and MFN2 mutation screening. There is insufficient evidence to determine the usefulness of routine genetic testing in patients with cryptogenic polyneuropathy who do not exhibit a hereditary neuropathy phenotype (Level U).
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Clinical Trial
Frontal FDG-PET activity correlates with cognitive outcome after STN-DBS in Parkinson disease.
Inconsistent changes of cognitive functioning have been reported in patients with Parkinson disease (PD) with deep brain stimulation (DBS) of the subthalamic nucleus (STN). To investigate the underlying pathomechanisms, we correlated alterations of cognitive test performance and changes of neuronal energy metabolism in frontal basal ganglia projection areas under bilateral STN stimulation. ⋯ These data show a significant linear relationship between changes in frontal 18-fluorodeoxyglucose PET activity and changes in cognitive outcome after deep brain stimulation of the subthalamic nucleus (STN) in advanced Parkinson disease. The best correlations were found in the left frontal lobe (dorsolateral prefrontal cortex and Broca area). Baseline performance on cognitive tests did not predict cognitive or metabolic changes after STN electrode implantation.