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Fernández-Espejo and colleagues investigate the differential neural substrates of overt and covert motor behavior and assess the structural integrity of the underlying networks in behaviorally nonresponsive patients. They used dynamic causal modeling of functional magnetic resonance imaging to compare voluntary motor imagery and motor execution. Their results suggest a possible biomarker for the absence of intentional movement in covertly aware patients (ie, specific damage to motor thalamocortical fibers), highlight the importance of the thalamus for the execution of intentional movements, and may provide a target for restorative therapies in behaviorally nonresponsive patients. Editorial perspective is provided by Nicholas D. Schiff, MD.
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Knopman and coauthors define the role of β-amyloidosis and neurodegeneration in the subsequent progression of topographic cortical structural and metabolic changes in mild cognitive impairment (MCI). They determine the regional 18fluorodeoxyglucose standardized uptake value ratio and gray matter volumes in medial temporal, lateral temporal, lateral parietal, and medial parietal regions. They find that persons with MCI who had elevated brain β-amyloidosis and neurodegeneration demonstrated volumetric and metabolic worsening in temporal and parietal association areas, consistent with the expectation that the MCI stage in the Alzheimer pathway heralds incipient isocortical involvement.
Devenney et al observe longitudinal outcomes and progression in probable and possible behavioral variant frontotemporal dementia (BVFTD) in accordance with international diagnostic criteria and identify features that may aid clinicians to prognosticate better in cases of possible BVFTD. Clinical, pathological, genetic, neuropsychological, and neuroimaging data were analyzed to categorize patients, to compare differences between groups with changed and unchanged diagnoses, to determine rates of progression in BVFTD, and to identify prognostic features in possible BVFTD. They conclude that BVFTD shows variable progression over time.
Callaghan and colleagues describe rare localizations of peripheral neuropathy, including the appropriate diagnostic evaluation and available treatments. References were identified from PubMed searches conducted on May 29, 2015, with an emphasis on systematic reviews and randomized clinical trials. They indicate that recognition of rare localizations of peripheral neuropathy is essential given the implications for diagnostic testing and treatment.
Highlights. JAMA Neurol. 2015;72(12):1391. doi:10.1001/jamaneurol.2014.2881