Arterial Spin-Labeling Perfusion Imaging in the Early Stage of Sturge-Weber Syndrome.

BACKGROUND AND PURPOSE: Sturge-Weber syndrome is a rare congenital neuro-oculo-cutaneous disorder. Although the principal mechanism of Sturge-Weber syndrome is characterized by a leptomeningeal vascular malformation, few data regarding perfusion abnormalities of the brain parenchyma are available. Therefore, the aim of this study was to assess the diagnostic performance of arterial spin-labeling perfusion imaging in the early stage of Sturge-Weber syndrome before 1 year of age until 3.5 years of age. We hypothesized that a leptomeningeal vascular malformation has very early hypoperfusion compared with controls with healthy brains. MATERIALS AND METHODS: We compared the CBF using arterial spin-labeling perfusion imaging performed at 3T MR imaging in the brain parenchymal regions juxtaposing the leptomeningeal vascular malformation in patients with Sturge-Weber syndrome (n = 16; 3.5 years of age or younger) with the corresponding areas in age-matched controls with healthy brains (n = 58). The analysis was performed following two complementary methods: a whole-brain voxel-based analysis and a visual ROI analysis focused on brain territory of the leptomeningeal vascular malformation. RESULTS: Whole-brain voxel-based comparison revealed a significant unilateral decrease in CBF localized in the affected cortices of patients with Sturge-Weber syndrome (P < .001). CBF values within the ROIs in patients with Sturge-Weber syndrome were lower than those in controls (in the whole cohort: median, 25 mL/100g/min, versus 44 mL/100g/min; P < .001). This finding was also observed in the group younger than 1 year of age, emphasizing the high sensitivity of arterial spin-labeling in this age window in which the diagnosis is difficult. CONCLUSIONS: Arterial spin-labeling perfusion imaging in the early stage of Sturge-Weber syndrome can help to diagnose the disease by depicting a cortical hypoperfusion juxtaposing the leptomeningeal vascular malformation.

Neural basis of interindividual variability in social perception in typically developing children and adolescents using diffusion tensor imaging.

Humans show great interindividual variability in the degree they engage in social relationship. The neural basis of this variability is still poorly understood, particularly in children. In this study, we aimed to investigate the neural basis of interindividual variability in the first step of social behavior, that is social perception, in typically developing children. For that purpose, we first used eye-tracking to objectively measure eye-gaze processing during passive visualization of social movie clips in 24 children and adolescents (10.5 ± 2.9 y). Secondly, we correlated eye-tracking data with measures of fractional anisotropy, an index of white matter microstructure, obtained using diffusion tensor imaging MRI. The results showed a large interindividual variability in the number of fixations to the eyes of characters during visualization of social scenes. In addition, whole-brain analysis showed a significant positive correlation between FA and number of fixations to the eyes,mainly in the temporal part of the superior longitudinal fasciculi bilaterally, adjacent to the posterior superior temporal cortex. Our results indicate the existence of a neural signature associated with the interindividual variability in social perception in children, contributing for better understanding the neural basis of typical and atypical development of a broader social expertise.

Social cognition and the superior temporal sulcus: implications in autism.

The most common clinical sign of autism spectrum disorders (ASD) is social interaction impairment, which is associated with communication deficits and stereotyped behaviors. Based on brain-imaging results, our hypothesis is that abnormalities in the superior temporal sulcus (STS) are highly implicated in ASD. These abnormalities are characterized by decreased grey matter concentration, rest hypoperfusion and abnormal activation during social tasks. STS anatomofunctional anomalies occurring early across brain development could constitute the first step in the cascade of neural dysfunctions underlying autism. It is known that STS is highly implicated on social perception processing, from perception of biological movements, such as body movements or eye gaze, to more complex social cognition processes. Among the impairments that can be described in social perception processing, eye gaze perception is particularly relevant in autism. Gaze abnormalities can now be objectively measured using eye-tracking methodology. In the present work, we will review recent data on STS contributions to normal social cognition and its implication in autism, with particular focus on eye gaze perception.

[Brain imaging of infantile autism]. / Imagerie cérébrale dans l'autisme infantile.

Understanding of brain structural anomalies seen in children with autism has considerably progressed since the apparition of MRI and functional imaging. All the results are converging toward the description of anatomical and functional anomalies in the regions of the so-called "social brain". Statistical analyses show diminution of gray matter in the region of the superior temporal sulcus (STS). Functional studies with PET shows a diminution of brain blood flow at rest in the same region. Brain activation studies show absence of activation of the specialized region in processing human voice and hypoactivation of "social brain" regions in complex tasks of social cognition. At last, abnormal connectivity between the frontal and temporal regions has been showed. Those regions are implicated in processing sensorial inputs necessary for normal social life. All those anomalies could be responsible of the abnormal social behaviour pattern of children with autism.