Men and women are different: diffusion tensor imaging reveals sexual dimorphism in the microstructure of the thalamus, corpus callosum and cingulum.

INTRODUCTION: Numerous magnetic resonance imaging (MRI) studies have addressed the question of morphological differences of the brain of men and women, reporting conflicting results regarding brain size and the ratio of gray and white matter. In the present study, we used diffusion tensor imaging (DTI) to delineate sex differences of brain white matter. METHODS: We investigated brain microstructure in 25 male and 25 female healthy subjects using a 3T MRI scanner. Whole-head DTI scans were analyzed without a-priori hypothesis using Tract-Based Spatial Statistics (TBSS) calculating maps of fractional anisotropy (FA), radial diffusivity (RD, a potential marker of glial alteration and changes in myelination) and axial diffusivity (AD, a potential marker of axonal changes). RESULTS: DTI revealed regional microstructural differences between the brains of male and female subjects. Those were prominent in the thalamus, corpus callosum and cingulum. Men showed significantly (p<0.0001) higher values of fractional anisotropy and lower radial diffusivity in these areas, suggesting that the observed differences are mainly due to differences in myelination. DISCUSSION: As a novel finding we showed widespread differences in thalamic microstructure that have not been described previously. Additionally, the present study confirmed earlier DTI studies focusing on sexual dimorphism in the corpus callosum and cingulum. All changes appear to be based on differences in myelination. The sex differences in thalamic microstructure call for further studies on the underlying cause and the behavioral correlates of this sexual dimorphism. Future DTI group studies may carefully control for gender to avoid confounding.

Topiramate in add-on therapy: results from an open-label, observational study.

An open-label, observational prospective study assessed the effectiveness of topiramate (TPM) as add-on therapy. A total of 450 patients aged 12 and above with a diagnosis of epilepsy and at least one epileptic seizure during the 12-week retrospective baseline were to be documented. After baseline evaluation, topiramate was added. Ninety-five percent of patients had at least one baseline AED, most commonly Carbamazepine (53%) or Valproate (34%). In 5% TPM was started in monotherapy. Topiramate dose titration and target dose was determined by clinical response and side effect profile. Patients were intended to be followed for a total of 1 year which included 6 visits during which seizure frequency, adverse events, weight as well as clinical global impression were recorded. During the 12 weeks retrospective baseline, a median of 2.8 seizures per month were recorded which reduced significantly to 0.7 per month during the complete treatment phase (p < 0.0001). Seventy-two percent of patients had a > or =50% seizure reduction. Ten percent of patients were seizure free during the study. The most commonly reported adverse events were difficulties with memory (4.2%), somnolence (3.6%), and dizziness (2.7%). Overall, topiramate was well tolerated, and only 5% of patients discontinued treatment due to an adverse event. Retention in the study was higher than previously reported during randomized, dose controlled studies and is likely due to individualized doses as well as slower titration used.

Vascular endothelial growth factor, hepatocyte growth factor/scatter factor, basic fibroblast growth factor, and placenta growth factor in human meningiomas and their relation to angiogenesis and malignancy.

OBJECTIVE: Angiogenesis is mediated by a number of different growth factors and appears vital for tumor growth. The understanding of angiogenic mechanisms could offer new therapeutic perspectives; in this context, the role of four potentially angiogenic growth factors was analyzed in a large series of meningiomas of different grades. METHODS: Vascular endothelial growth factor (VEGF), placenta growth factor, hepatocyte growth factor/scatter factor, and basic fibroblast growth factor were quantified in 69 tumors by enzyme-linked immunosorbent assay. Microvessel density and proliferative activity were determined on paraffin sections, and clinical tumor invasiveness was rated. Induction of endothelial chemotaxis and capillary-like tube formation were studied in vitro using modified Boyden chamber assays and three-dimensional collagen gel assays, respectively. RESULTS: Tumors included 40 benign (World Health Organization [WHO] Grade I), 21 atypical (WHO Grade II), and 8 anaplastic/malignant (WHO Grade III) meningiomas. We found a correlation between meningioma grade and VEGF content (r = 0.37, P = 0.002), which was 2-fold higher in atypical than in benign meningiomas (P = 0.022) and 10-fold higher in malignant than in benign meningiomas (P = 0.025). Among different subtypes of Grade I meningiomas, VEGF levels were 10-fold higher in meningothelial than in fibrous meningiomas (P = 0.015). None of the other three factors investigated showed any association with tumor grade, microvessel density, or invasiveness, and VEGF also did not correlate with vascularity or invasiveness. Moreover, vascularity did not increase with malignancy grade. Endothelial chemotaxis and capillary-like tube formation in vitro were induced by meningioma extracts and were most effectively blocked by co-addition of antibodies against basic fibroblast growth factor, followed by anti-VEGF, whereas anti-hepatocyte growth factor/scatter factor was not effective. The chemotactic activity of meningioma extracts on endothelial cells correlated with their VEGF content (r = 0.6, P = 0.003). CONCLUSION: Meningiomas do not show an angiogenic switch involving VEGF and/or hepatocyte growth factor/scatter factor, as has previously been found in gliomas. Nevertheless, the biological activity of VEGF and basic fibroblast growth factor in meningiomas suggests that both are potential targets for antiangiogenic therapy in meningiomas of all WHO grades.