Microstructural damage of the posterior corpus callosum contributes to the clinical severity of neglect

Bozzali, Marco, Mastropasqua, Chiara, Cercignani, Mara, Giulietti, Giovanni, Bonnì, Sonia, Caltagirone, Carlo and Koch, Giacomo (2012) Microstructural damage of the posterior corpus callosum contributes to the clinical severity of neglect. PLoS ONE, 7 (10). e48079. ISSN 1932-6203

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Abstract

One theory to account for neglect symptoms in patients with right focal damage invokes a release of inhibition of the right parietal cortex over the left parieto-frontal circuits, by disconnection mechanism. This theory is supported by transcranial magnetic stimulation studies showing the existence of asymmetric inhibitory interactions between the left and right posterior parietal cortex, with a right hemispheric advantage. These inhibitory mechanisms are mediated by direct transcallosal projections located in the posterior portions of the corpus callosum. The current study, using diffusion imaging and tract-based spatial statistics (TBSS), aims at assessing, in a data-driven fashion, the contribution of structural disconnection between hemispheres in determining the presence and severity of neglect. Eleven patients with right acute stroke and 11 healthy matched controls underwent MRI at 3T, including diffusion imaging, and T1-weighted volumes. TBSS was modified to account for the presence of the lesion and used to assess the presence and extension of changes in diffusion indices of microscopic white matter integrity in the left hemisphere of patients compared to controls, and to investigate, by correlation analysis, whether this damage might account for the presence and severity of patients' neglect, as assessed by the Behavioural Inattention Test (BIT). None of the patients had any macroscopic abnormality in the left hemisphere; however, 3 cases were discarded due to image artefacts in the MRI data. Conversely, TBSS analysis revealed widespread changes in diffusion indices in most of their left hemisphere tracts, with a predominant involvement of the corpus callosum and its projections on the parietal white matter. A region of association between patients' scores at BIT and brain FA values was found in the posterior part of the corpus callosum. This study strongly supports the hypothesis of a major role of structural disconnection between the right and left parietal cortex in determining 'neglect'.

Item Type: Article
Schools and Departments: Brighton and Sussex Medical School > Clinical and Experimental Medicine
Brighton and Sussex Medical School > Neuroscience
Subjects: R Medicine
Depositing User: Patricia Butler
Date Deposited: 13 May 2013 14:08
Last Modified: 26 Sep 2017 13:13
URI: http://sro.sussex.ac.uk/id/eprint/44673

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