Abstract 3577: Lesions in White Matter Tracts Contralateral to the Ischemic Vascular Injury

Abstract

Background: The phenomenon of diaschisis, with wallerian degeneration, can increase the brain lesion burden in unilateral vascular ischemic lesion leading to contralateral damage. Diffusion tensor imaging (DTI) allows the visualization and measurement of white matter lesions. We tested the hypothesis that there are white matter tracts lesions in the hemisphere contralateral to the ischemic lesion. Methods: Patients with unilateral ischemic lesions, who had performed a diagnostic MRI including DTI sequence (Philips Achieva 3T, Best, Netherlands) from August 2009 to April 2010 were selected. A neuroradiologist analyzed the images and selected the ones with unilateral ischemic lesion on middle cerebral artery territory. For comparisons, images of healthy-control subjects with similar age, from the local neuroimaging laboratory, were used. The DTI images (TR=8500, TE=61, 2mm of slice thickness, 32 directions, b-factor 1000) were analyzed using a tract based statistical study (TBSS, fMRIB software library, Oxford, UK). After image alignment and mapping, the fractional anisotropy values were compared in order to detect possible differences in the white matter tracts between patients and controls. P values < 0.05 were considered as statistically significant. Results: Thirty seven patients (11 women) with mean age of 60 years (range, 25- 79 years) and 24 controls (11 women) with mean age of 58 years (range, 49- 70) were studied. Twenty of the 37 patients had ischemic lesions on the right hemisphere. Leukoaraiosis was present in all stroke patients. Differences of fractional anisotropy between patients and controls were detected on the ipsilateral hemisphere but also in the hemisphere contralateral to the ischemic lesion and outside the middle cerebral artery territory (p < 0.05). Conclusions: Patients with unilateral ischemic lesions present changes of the white matter integrity in both hemispheres. Contralateral white matter lesions are seen beyond ipsilateral middle cerebral artery territory, which suggests a diaschisis phenomenon or a diffuse microvascular involvement.