Background: Functional imaging methods, such as resting-state functional magnetic resonance imaging, reflect changes in neural connectivity and may help to assess the widespread consequences of disease-specific network changes in Parkinson's disease. In this study we used a relatively new graph analysis approach in functional imaging: eigenvector centrality mapping. This model-free method, applied to all voxels in the brain, identifies prominent regions in the brain network hierarchy and detects localized differences between patient populations. In other neurological disorders, eigenvector centrality mapping has been linked to changes in functional connectivity in certain nodes of brain networks.Objectives: Examining changes in functional brain connectivity architecture on a whole brain and network level in patients with Parkinson's disease.Methods: Whole brain resting-state functional architecture was studied with a recently introduced graph analysis approach (eigenvector centrality mapping). Functional connectivity was further investigated in relation to eight known resting-state networks. Cross-sectional analyses included group comparison of functional connectivity measures of Parkinson's disease patients (n = 107) with control subjects (n = 58) and correlations with clinical data, including motor and cognitive impairment and a composite measure of predominantly non-dopaminergic symptoms.Results: Eigenvector centrality mapping revealed that frontoparietal regions were more prominent in the whole-brain network function in patients compared to control subjects, while frontal and occipital brain areas were less prominent in patients. Using standard resting-state networks, we found predominantly increased functional connectivity, namely within sensorimotor system and visual networks in patients. Regional group differences in functional connectivity of both techniques between patients and control subjects partly overlapped for highly connected posterior brain regions, in particular in the posterior cingulate cortex and precuneus. Clinico-functional imaging relations were not found.Conclusions: Changes on the level of functional brain connectivity architecture might provide a different perspective of pathological consequences of Parkinson's disease. The involvement of specific, highly connected (hub) brain regions may influence whole brain functional network architecture in Parkinson's disease.

BackgroundIn Parkinson's disease (PD), the relation between cortical brain atrophy on MRI and clinical progression is not straightforward. Determination of changes in structural covariance networks - patterns of covariance in grey matter density - has shown to be a valuable technique to detect subtle grey matter variations. We evaluated how structural network integrity in PD is related to clinical data.Methods3 Tesla MRI was performed in 159 PD patients. We used nine standardized structural covariance networks identified in 370 healthy subjects as a template in the analysis of the PD data. Clinical assessment comprised motor features (Movement Disorder Society-Unified Parkinson's Disease Rating Scale; MDS-UPDRS motor scale) and predominantly non-dopaminergic features (SEverity of Non-dopaminergic Symptoms in Parkinson's Disease; SENS-PD scale: postural instability and gait difficulty, psychotic symptoms, excessive daytime sleepiness, autonomic dysfunction, cognitive impairment and depressive symptoms). Voxel-based analyses were performed within networks significantly associated with PD.ResultsThe anterior and posterior cingulate network showed decreased integrity, associated with the SENS-PD score, p = 0.001 (β = − 0.265, ηp2 = 0.070) and p = 0.001 (β = − 0.264, ηp2 = 0.074), respectively. Of the components of the SENS-PD score, cognitive impairment and excessive daytime sleepiness were associated with atrophy within both networks.ConclusionsWe identified loss of integrity and atrophy in the anterior and posterior cingulate networks in PD patients. Abnormalities of both networks were associated with predominantly non-dopaminergic features, specifically cognition and excessive daytime sleepiness. Our findings suggest that (components of) the cingulate networks display a specific vulnerability to the pathobiology of PD and may operate as interfaces between networks involved in cognition and alertness.

PurposeToday, 40 to 66 % of elective procedures in abdominal surgery are reoperations. Reoperations show increased operative time and risk for intraoperative and postoperative complications, mainly due to the need to perform adhesiolysis. It is important to understand which patients will require repeat surgery for optimal utilization and implementation of anti-adhesive strategies. Our aim is to assess the incidence and identify risk factors for repeat abdominal surgery.MethodsThis is the long-term follow-up of a prospective cohort study (Laparotomy or Laparoscopy and Adhesions (LAPAD) study; clinicaltrials.gov NCT01236625). Patients undergoing elective abdominal surgery were included. Primary outcome was future repeat abdominal surgery and was defined as any operation where the peritoneal cavity is reopened. Multivariable logistic regression analysis was used to identify risk factors.ResultsSix hundred four (88 %) out of 715 patients were included; median duration of follow-up was 46 months. One hundred sixty (27 %) patients required repeat abdominal surgery and underwent a total of 234 operations. The indication for repeat surgery was malignant disease recurrence in 49 (21 %), incisional hernia in 41 (18 %), and indications unrelated to the index surgery in 58 (25 %) operations. Older age (OR 0.98; p 0.002) and esophageal malignancy (OR 0.21; p 0.034) significantly reduced the risk of undergoing repeat abdominal surgery. Female sex (OR 1.53; p 0.046) and hepatic malignancy as indication for surgery (OR 2.08; p 0.049) significantly increased the risk of requiring repeat abdominal surgery.ConclusionsOne in four patients will require repeat surgery within 4 years after elective abdominal surgery. Lower age, female sex, and hepatic malignancy are significant risk factors for requiring repeat abdominal surgery.

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