The corpus callosum in Binswanger's disease: A quantitative fractional anisotropy analysis

Dementia & Neuropsychologia 2008 December;2(4):278-283 The corpus callosum in Binswanger’s disease A quantitative fractional anisotropy analysis Eliasz Engelhardt1, Denise Madeira Moreira2,3, Gilberto Oliveira Alves5, Maria Elisa Oliveira Lanna6, Carlos Eduardo de Oliveira Alves7, Letice Ericeira-Valente8, Felipe Kenji Sudo9, Jerson Laks4,10 Abstract – To study the integrity of the corpus callosum in Binswanger’s disease (BD) patients using quantitative fractional anisotropy (DTI-FA). Methods: Controls (12) and patients with BD (12) were included. MR [GE Signa Horizon-1.5T] scans were performed. BD patients presented Fazekas’s score=6 and leukoaraiosis extension ≥75%, as assessed on FLAIR sequence. Standard parameters for DTI-FA acquisition were used. Functool was employed for post-processing, and ROIs placed on the genu and splenium of the corpus callosum on one axial plane at the basal ganglia level. Statistics [ANOVA] for genu and splenium comparison were analyzed. Results: DTI-FA showed reduction of anisotropy in both regions of the corpus callosum, more prominently in anterior (genu) than posterior (splenium) in BD patients versus controls. Conclusion: The reduction of anisotropy reflects loss of integrity of fibers of the studied regions of the corpus callosum. This finding indicates an interruption of the most important inter-hemispheric commissure, and component of neural networks that underlies cognitive, behavioral, motor and sensory integration. The affected genu and splenium, together with damage to other fiber systems that connect the prefrontal and parietal-occipital regions, may manifest clinically as dysfunction of high-level integrative regions linked to the domains of executive and sensory functions, respectively, that can occur in Binswanger’s disease. Key words: Binswanger’s disease, corpus callosum, genu, splenium, diffusion tensor, fractional anisotropy. O corpo caloso na doença de Binswanger: uma análise com anisotropia fracionada quantitativa Resumo – Estudar a integridade do corpo caloso em pacientes com doença de Binswanger (DB) com anisotropia fracionada quantitativa (DTI-FA). Métodos: Foram incluídos controles (12) e pacientes com DB (12). Imagens de RM [GE Signa Horizon-1,5T] foram obtidas. Os pacientes com DB apresentavam escore=6 de Fazekas e leucoaraiose com extensão ≥75% como avaliado na seqüência em FLAIR. Foram utilizados parâmetros padrão para DTI-FA e utilizado Functool para pós-processamento. ROIs localizados no joelho e no esplênio do corpo caloso em um plano axial no nível dos gânglios da base. Estatística [ANOVA] feita para comparar joelho e esplênio. Resultados: DTI-FA mostrou redução da anisotropia em ambas as regiões do corpo caloso, com predomínio na anterior (joelho) em relação à posterior (esplênio), nos pacientes com DB em comparação aos controles. Conclusões: A redução da anisotropia reflete perda da integridade de fibras das regiões estudadas do corpo caloso. Esses achados indicam interrupção da mais importante comissura inter-hemisférica e componente de redes neurais subjacentes à integração cognitiva, comportamental e de funções motora e sensorial. O comprometimento do joelho e do esplênio, juntamente com a lesão de outros sistemas de fibras, que conectam regiões pré-frontais e parietooccipitais, podem ser expressas clinicamente por disfunção de regiões de alto nível de integração, relacionadas aos domínios das funções executiva e sensorial, respectivamente, que pode ocorrer na doença de Binswanger. Palavras-chave: doença de Binswanger, corpo caloso, joelho, esplênio, tensor de difusão, anisotropia fracionada. The corpus callosum is the largest fiber tract, and the main commissure, of the human brain, interconnecting neocortical areas of both hemispheres. The free part (midline) of the corpus callosum is easily visible (better seen in midsagital cuts), and includes a medial and a lateral part (defined as the region adjoining the callosal recess). From here the fibers spread out as the radiations of the corpus callosum that merge into the hemispheric white matter Center for Alzheimer’s Disease / Institute of Psychiatry/Federal University of Rio de Janeiro; School of Medical Sciences, State University of Rio de Janeiro. Institute of Neurology Deolindo Couto of the Federal University of Rio de Janeiro. 1-10 Eliasz Engelhardt – Rua Barata Ribeiro, 370/504 - 22040-000 Rio de Janeiro RJ - Brazil. E-mail: Received September 24, 2008. Accepted in final form November 12, 2008. 278     Binswanger’s disease     Engelhardt E, et al. Dement Neuropsychol 2008 December;2(4):278-283 where they intermingle with other tracts in the centrum semiovale and with the fibers of the corona radiata. It may be divided into roughly three regions, anterior (incorporating the genum), intermediary (body), and posterior (incorporating the splenium). The genu connects the prefrontal regions, the body connects the posterior portion of the frontal lobes and the parietal lobes, while the splenium connects regions of the parietal and occipital lobes.1-4 The corpus callosum establishes inter-hemispheric connections in a topographically organized way, and functionally information transfer takes place between areas related to cognition, behavior, motor and sensory functions.2,5-9 This commissure is provided with a rich arterial supply through the pericallosal, posterior pericallosal, and the anterior communicating arteries. They form the pericallosal pial plexus that supplies the midline corpus callosum and part of its radiations. The midline of the corpus callosum also presents a specific microvascular supply that boosts its vascularization. The vascular supply to the central zone of the genu and body of the corpus callosum, via short penetrating arterioles, is similar to that of the cerebral cortex, whereas the vascular supply to the extreme lateral corpus callosum and centrum semiovale is largely carried by medullary arteries, long end-arteries without anastomoses.4,10-12 The corpus callosum may be affected by numerous diseases, including those of vascular etiology. Infarctions and atrophy as a consequence of widespread subcortical white matter ischemic diseases, such as Binswanger’s disease, may also occur.3,13 Binswanger’s disease (BD) is one of several subtypes of the vascular cognitive impairment-vascular dementia (VCI-VaD) continuum.14-15 Pathological examination of BD brains reveal atrophy, and the cut sections show an enlarged ventricular system, hypotrophy and yellowish discoloration of the subcortical white matter, and a thinned corpus callosum.16 The thinning of the corpus callosum is often secondary, and primary white matter lesions have not been reported in this region.3,17 The microscopic neuropathology of white matter lesions is mainly characterized by diffuse loss of nerve fibers, demyelination and gliosis affecting the centrum semiovale and the corpus callosum in a differentiated way.3,16,18-20 The lateral part of the corpus ca (...truncated)