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Mapping corpus callosum morphology and its neurocognitive
correlates: The effects of prenatal alcohol exposure
Source: Neuroscience Abstract 2000 Apr;26:79.
Author: Sowell ER, Mattson SN, Thompson PM, Jernigan TL, Riley EP, Toga AW.
Abstract:
Summary: Abnormalities of the corpus callosum (CC) have been documented in fetal alcohol syndrome (FAS). Subtle abnormalities in its size have been observed in some individuals and partial to complete agenesis have been observed in others. The purpose of this study was to investigate abnormalities, not only in the size of the CC, but also in the shape and location of this structure in individuals with FAS, as well as those prenatally exposed to high amounts of alcohol but without FAS (the PEA group). Magnetic resonance imaging (MRI) and novel surface-based mesh modeling image analytic methods were used. Twenty alcohol-exposed subjects (7 with PEA and 13 with FAS; age 8 to 22 years) along with 21 normal controls (8 to 25 years) were studied with high resolution MRI and cognitive measures of verbal learning and visuospatial abilities. Results indicate that in addition to callosal area reductions that are regionally specific and most severe in the splenium, the CC is significantly displaced in patients prenatally exposed to alcohol. Specifically, the CC lies more anterior and inferior on the order of 5 to 7 mm out of place in posterior callosal regions in the alcohol exposed group with relatively normal localization of the genu and anterior body regions. These findings are robust in the FAS patients studied, and a similar, but less severe pattern of results is observed in the PEA patients. For the first time in this report we show that the amount of callosal displacement is highly correlated with impairment in verbal learning ability, and that callosal displacement is a better predictor of cognitive functioning than regional callosal area. The brain-behavior relationship is only significant within the alcohol-exposed group, and notably, the effect is not mediated by overall impaired intellectual functioning in the patients. These results further emphasize the vulnerability of midline brain structures to prenatal alcohol exposure. They also indicate that neuroanatomical dysmorphology and its resultant cognitive impairment is not dependent on the presence of the hallmark facial dysmorphology required for the diagnosis of FAS. Introduction: Prenatal exposure to alcohol is known to cause neurological and cognitive impairment and physical abnormalities to varying degrees. Fetal alcohol syndrome (FAS) is diagnosed in the most severe cases when prenatal or postnatal growth deficiency, central nervous system (CNS) abnormalities, and craniofacial dysmorphology are observed. Post mortem studies of FAS patients have revealed brain abnormalities, most commonly, microcephaly, but also abnormalities of the corpus callosum (CC) and cerebellum. Notably, partial or even complete agenesis of the CC is not uncommon in FAS patients studied post mortem relative to those with other developmental disorders. More recently, magnetic resonance imaging studies have shown complete agenesis in several living children with FAS. In the present study, we assessed callosal abnormality in children, adolescents and young adults prenatally exposed to alcohol both with and without FAS using high resolution MRI and novel image analytic techniques. In addition to the more traditional regional area measurements, we also used algorithms that rely on surface or edge deformation in order to assess abnormalities in the shape and location of the CC within the brain. These methods allow a comprehensive analysis of callosal structure and further allow visualization of structural differences between groups of patients in a 3-dimensional coordinate system that may be independent of differences in callosal size measures. Methods: The patient group consisted of 20 children, adolescents, and young adults between the ages of 8 and 22 years. All of them had a history of behavioral problems, cognitive impairments, and heavy prenatal alcohol exposure. MR was performed with a 1.5 Tesla magnet. Most children were given the California Verbal Learning Test for Children and the Rey Osterrieth Complex Figure as part of a battery of tests administered by a large multidisciplinary neurodevelopmental research center, or as part of a larger project studying the effects of prenatal alcohol exposure. Discussion: Results from this study show regionally specific callosal area reduction and displacement in posterior isthmus and splenial regions, with relative sparing in the localization of the anterior body and genu.
Source: Neuroscience Abstract 2000 Apr;26:79.
Author: Sowell ER, Mattson SN, Thompson PM, Jernigan TL, Riley EP, Toga AW.
Abstract:
Summary: Abnormalities of the corpus callosum (CC) have been documented in fetal alcohol syndrome (FAS). Subtle abnormalities in its size have been observed in some individuals and partial to complete agenesis have been observed in others. The purpose of this study was to investigate abnormalities, not only in the size of the CC, but also in the shape and location of this structure in individuals with FAS, as well as those prenatally exposed to high amounts of alcohol but without FAS (the PEA group). Magnetic resonance imaging (MRI) and novel surface-based mesh modeling image analytic methods were used. Twenty alcohol-exposed subjects (7 with PEA and 13 with FAS; age 8 to 22 years) along with 21 normal controls (8 to 25 years) were studied with high resolution MRI and cognitive measures of verbal learning and visuospatial abilities. Results indicate that in addition to callosal area reductions that are regionally specific and most severe in the splenium, the CC is significantly displaced in patients prenatally exposed to alcohol. Specifically, the CC lies more anterior and inferior on the order of 5 to 7 mm out of place in posterior callosal regions in the alcohol exposed group with relatively normal localization of the genu and anterior body regions. These findings are robust in the FAS patients studied, and a similar, but less severe pattern of results is observed in the PEA patients. For the first time in this report we show that the amount of callosal displacement is highly correlated with impairment in verbal learning ability, and that callosal displacement is a better predictor of cognitive functioning than regional callosal area. The brain-behavior relationship is only significant within the alcohol-exposed group, and notably, the effect is not mediated by overall impaired intellectual functioning in the patients. These results further emphasize the vulnerability of midline brain structures to prenatal alcohol exposure. They also indicate that neuroanatomical dysmorphology and its resultant cognitive impairment is not dependent on the presence of the hallmark facial dysmorphology required for the diagnosis of FAS. Introduction: Prenatal exposure to alcohol is known to cause neurological and cognitive impairment and physical abnormalities to varying degrees. Fetal alcohol syndrome (FAS) is diagnosed in the most severe cases when prenatal or postnatal growth deficiency, central nervous system (CNS) abnormalities, and craniofacial dysmorphology are observed. Post mortem studies of FAS patients have revealed brain abnormalities, most commonly, microcephaly, but also abnormalities of the corpus callosum (CC) and cerebellum. Notably, partial or even complete agenesis of the CC is not uncommon in FAS patients studied post mortem relative to those with other developmental disorders. More recently, magnetic resonance imaging studies have shown complete agenesis in several living children with FAS. In the present study, we assessed callosal abnormality in children, adolescents and young adults prenatally exposed to alcohol both with and without FAS using high resolution MRI and novel image analytic techniques. In addition to the more traditional regional area measurements, we also used algorithms that rely on surface or edge deformation in order to assess abnormalities in the shape and location of the CC within the brain. These methods allow a comprehensive analysis of callosal structure and further allow visualization of structural differences between groups of patients in a 3-dimensional coordinate system that may be independent of differences in callosal size measures. Methods: The patient group consisted of 20 children, adolescents, and young adults between the ages of 8 and 22 years. All of them had a history of behavioral problems, cognitive impairments, and heavy prenatal alcohol exposure. MR was performed with a 1.5 Tesla magnet. Most children were given the California Verbal Learning Test for Children and the Rey Osterrieth Complex Figure as part of a battery of tests administered by a large multidisciplinary neurodevelopmental research center, or as part of a larger project studying the effects of prenatal alcohol exposure. Discussion: Results from this study show regionally specific callosal area reduction and displacement in posterior isthmus and splenial regions, with relative sparing in the localization of the anterior body and genu.