Diffusion-weighted imaging abnormalities in the corpus callosum after neonatal seizure: a case report

We report a patient with a neonatal seizure in whom diffusion-weighted imaging (DWI) at 8 days of age revealed high-intensity areas in the genu and splenium of the corpus callosum. The patient was a 2-day-old girl born at 39 weeks of gestational age. No apparent signs of asphyxia were found at birth. Clinically, she had a clonic seizure of the left hemisphere, with open eyes deviating to the left, and automatism around the mouth. The antiepileptic drug phenobarbital was administered once, her seizure was simultaneously stopped. Because she was a newborn, her corpus callosum was not completely myelinated. Intramyelinic edema was not responsible for these DWI findings; the mechanism of the abnormal DWI findings was clearly unknown. Here, we present abnormal DWI findings in the corpus callosum in a neonatal seizure case that did not meet all the criteria for neonatal hypoxic-ischemic encephalopathy (HIE).     

Assessing sequence and relationship of regional maturation in corpus callosum and internal capsule in preterm and term newborns by diffusion-tensor imaging

BackgroundDiffusion-tensor imaging (DTI) can be used to investigate water diffusion in living tissue.ObjectiveTo investigate sequence and relationship of regional maturation in corpus callosum (CC) and internal capsule (IC) in preterm and term.MethodsDTI was performed on 11 preterm infants at less than 37 weeks of corrected gestational age (group I), 21 preterm infants at equivalent-term (group II), 11 term infants during neonatal period (group III). Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were measured in: anterior limb of IC (ALIC), posterior limb of IC (PLIC), genu and splenium of CC.ResultsFA in splenium was more than that in other regions except genu of group I. Differences of FA between genu and PLIC were significant only in group III. ADC in genu was more than that in other regions but in splenium of groups I and II. Differences of ADC between splenium and ALIC were insignificant except group II. Higher FA and lower ADC in PLIC were gotten compared with those in ALIC. Correlations of FA and of ADC existed in CC and IC.ConclusionMaturation sequence was splenium followed by genu, then by PLIC and last by ALIC in term at neonatal period. Genu's maturation in preterm at equivalent-term was hindered. Regional maturation's correlations existed in CC and IC.     

健康成人胼胝体核磁共振影像解剖学研究

目的 探讨健康成人胼胝体各部分径值及与年龄的相关性,为相关疾病的诊断提供正常胼胝体数据. 方法 选择120例健康成人自愿者(男、女各半),行头部T1加权序列MR扫描.在正中矢状面上测量胼胝体的膝部、压部、体部的宽度以及胼胝体长度与高度. 结果 120例健康成人胼胝体膝部、压部、体部的宽度以及胼胝体长度与高度分别为(11.35±2.16) mm、(9.97±2.09)mm、(5.93±1.32)mm、(73.33±3.77)mm、(25.34±3.01)mm.经统计学分析发现健康成人腩随年龄的增加胼胝体的膝部、乐部、体部的宽度逐渐减小,而胼胝体的长度与高度随年龄增加而增加,呈显著相关性(P<0.05).胼胝体形态随年龄的增长而呈弓背样增高. 结论 胼胝体的各部分径值及形态与年龄密切相关.     

Shape and size of the corpus callosum in schizophrenia and schizotypal personality disorder

The size and shape of the corpus callosum were assessed on sagittal section magnetic resonance images in 27 patients with schizophrenia, 13 patients with schizotypal personality disorder (SPD), and 30 healthy volunteers. High-resolution 1.2mm axial SPGR images were acquired and resectioned so that the sagittal plane passed through the anterior and posterior commissures and was parallel to the interhemispheric fissure. The corpus callosum and the whole brain were traced on midsagittal section slices of each brain, and the callosum was divided into 30 anteroposterior sectors. Pixel-by-pixel chi-square and thin-plate spline analyses were used to assess between-group shape differences. Size of the corpus callosum was smaller anteriorly in the genu of the corpus callosum and posteriorly in the splenium in schizophrenic patients than in normal controls. The genu of the corpus callosum was larger in SPD patients than in schizophrenic patients or normal controls. The posterior corpus callosum was largest in normal controls, smaller in SPD patients, and smallest in schizophrenic patients. Shape analysis was consistent with these size comparisons, and suggested a downward bowing of the corpus callosum in schizophrenic and SPD patients. SPD patients also had a region of the callosum just posterior to the genu that was narrower than in the other two groups. The decreases in corpus callosal size in schizophrenia varied directly with length of illness, perhaps indicative of a progressive process. The patient-control differences in callosal size and shape are consistent with a hypothesis of decreased connectivity between the left and the right hemispheres in schizophrenia and SPD.     

Corpus callosum and prefrontal functions in adolescents with history of very preterm birth

Very preterm (VPT) birth can account for thinning of the corpus callosum and poorer cognitive performance. Research findings about preterm and VPT adolescents usually describe a small posterior corpus callosum, although our research group has also found reductions of the anterior part, specifically the genu. The aim of the present study was to investigate the functional implications of this concrete reduction. Fifty-two VPT adolescents were compared with 52 adolescents born at term; there were no significant differences in age and gender, and socioeconomic status was similar between the groups. All participants underwent a magnetic resonance imaging (MRI) study and assessment of prefrontal functioning and vocabulary. The VPT group showed significant reductions of the genu, isthmus and splenium, as well as a significantly worse performance on category verbal fluency, executive functions, everyday memory and vocabulary. Although several parts of the corpus callosum correlated with some prefrontal functions, the genu was the part which principally explained these correlations. The subtest Vocabulary only correlated with the splenium. The relationship between genu and prefrontal functions and between splenium and vocabulary may be due to the fact that these parts of the corpus callosum connect prefrontal and posterior parietal cortex, respectively. The work presented here provides evidence of specific associations between reductions in the anterior corpus callosum (genu) and lower prefrontal functioning in VPT adolescents.     

Gestational age at preterm birth in relation to corpus callosum and general cognitive outcome in adolescents

Prematurity is associated with corpus callosum abnormalities and low general cognitive functioning. The present study explores the specific relationship between gestational age, corpus callosum, and intelligence quotient (IQ) in a sample of preterm-born adolescents. Sixty-four adolescents born at a gestational age of 36 weeks or less were divided into 4 groups attending to their gestational age (GA) (group 1, < or = 27; group 2, 28-30; group 3, 31-33; group 4, 34-36). These individuals were compared with 53 adolescents born at term and of similar age, gender, and sociocultural status. Individuals born at a gestational age of 27 or less (group 1) presented a generalized corpus callosum reduction in the posterior part (posterior midbody, isthmus, and splenium) as well as in the anterior part (anterior midbody and genu), a reduced total white-matter volume, and a low Full-Scale IQ. Group 2 (GA between 28 and 30) also showed a low IQ, but corpus callosum reduction was only found in the splenium, without total white-matter volume reductions. Group 3 (GA between 31 and 33) did not present differences in corpus callosum size or a reduced total white- matter volume, but they showed a low Full-Scale IQ. Group 4 (GA between 34 and 36) did not show a smaller corpus callosum or a lower general cognitive performance. Specific significant correlations were found between corpus callosum subregions and gestational age. These results suggest the importance of gestational age in prematurity in relation to brain structural and functional outcome. Premature babies born at a gestational age of 27 weeks or less are the target group for long-term corpus callosum and white-matter anomalies and for a low IQ.     

Corpus callosum atrophy and cerebral blood flow in chronic alcoholics

The corpus callosum atrophy and cerebral blood flows were investigated in chronic alcoholics without Marchiafava-Bignami disease. Fifteen cases of chronic alcoholics and 15 age-matched healthy controls were studied. The sagittal plane of magnetic resonance imaging of the head was scanned into a computer and the corpus callosum was measured and the callosal index was calculated. Cerebral blood flows were measured using stable xenon computed tomography (CT) method. Regional cerebral blood flows in the frontal, temporal, parietal and occipital cortex, frontal, temporal and occipital white matter, caudate nucleus, putamen and thalamus were measured. The corpus callosum area, the thickness of the genu, the thickness of the trunk, the thickness of the splenium, and the callosal index were significantly smaller in the chronic alcoholic group than in the healthy control group. Blood flows in the cerebral cortex, thalamus and putamen were significantly lower in the chronic alcoholic group than in the healthy control group. Significant positive correlations were present between the corpus callosum atrophy and the cerebral cortex blood flows. Corpus callosum atrophy and decreased cerebral blood flows may be seen in chronic alcoholics without Marchiafava-Bignami disease.     

White-matter alterations and callosal abnormalities in syndromic patients with mental retardation

The aim of this study was to evaluate the frequency of callosal abnormalities and white matter alterations in syndromic patients. The authors report on the cerebral magnetic resonance imaging (MRI) morphologic analysis of the corpus callosum and white matter in 73 normal subjects and 61 syndromic patients. The study of the corpus callosum was carried out by MRI using different morphometric methods: measurement of the dimensions of length and thickness of genu, body, and splenium; measurement of angles obtained using the sagittal plane; and application of the proportional grid of Talairach. The evaluation of the white matter was carried out by applying a subjective grading scale. Abnormalities of the corpus callosum were found in about 50% of the syndromic subjects; in half of these cases, the abnormalities were associated with white matter alterations. In five syndromic patients (8.2%), the white matter alterations were not associated with corpus callosum abnormalities. This study shows that corpus callosum abnormalities are frequent in syndromology regardless of the syndrome type.     

胼胝体变性的临床特点与影像学特征研究

目的　研究分析了一组胼胝体变性 (MBD)患者的临床表现和影像学特征 ,探讨不同临床分型的特点与诊断方法。方法　 4例长期酗酒男性MBD患者 ,急性型 1例 ,慢性型 3例 ,均经CT检查 ,3例经头MR检查 ,1例行尸检病理检查。结果　急性型主要表现为意识障碍、精神症状与癫 ;慢性型以痴呆、精神症状为主要表现 ;CT与MR可见胼胝体膝部和压部病灶。CT病灶为低密度 ,MR表现为T1WI低信号 ;T2 WI高信号 ;2例伴发双侧大脑半球白质对称性病灶 ,1例出现脑干对称性病灶。尸检病理提示 :胼胝体呈多灶性脱髓鞘与坏死改变。结论　急性型MBD意识障碍突出 ,病程进展迅速 ;慢性型以痴呆、精神症状和锥体束损害为主要表现 ;CT与MR为其生前诊断的主要手段 ,以胼胝体膝部、压部对称性病灶为其主要异常表现。     

Quantitative analysis of myelinated axons of corpus callosum in the human brain

In this study, the myelinated axons of the rostrum, genu, truncus and splenium parts of the corpus callosum were counted in the human brain by using a camera lucida. The numerical densities of these axons were compared with each other by means of quantitative analytical statistical methods. The number of myelinated axons of genu and truncus of the corpus callosum were found to be highest in number and they were nearly the same with each other. However, number of the myelinated axons of splenium was found to be lower in number, when compared with the other parts of corpus callosum.     

QUANTITATIVE ANALYSIS OF MYELINATED AXONS OF CORPUS CALLOSUM IN THE HUMAN BRAIN

In this study, the myelinated axons of the rostrum, genu, truncus and splenium parts of the corpus callosum were counted in the human brain by using a camera lucida. The numerical densities of these axons were compared with each other by means of quantitative analytical statistical methods. The number of myelinated axons of genu and truncus of the corpus callosum were found to be highest in number and they were nearly the same with each other. However, number of the myelinated axons of splenium was found to be lower in number, when compared with the other parts of corpus callosum.     

Transiently reduced water diffusion in the corpus callosum in infants with benign partial epilepsy in infancy

Neuroimaging findings are usually normal in children with benign partial epilepsy in infancy. However, we found a transient reduction of water diffusion in the corpus callosum in two patients with probable benign partial epilepsy in infancy. The patients were admitted to our hospital because of seizure clusters. No delay in the developmental milestones was seen, and no neurological abnormalities were observed during the interictal period. Interictal electroencephalography was normal in both infants. However, the diffusion-weighted images showed abnormal high intensities in both the genu and splenium in one patient and in the splenium only in the other. No diffusion abnormalities were observed in follow-up magnetic resonance imaging. The clustered seizures may be related to the transient callosal lesions seen in our patients.     

Neuropathological abnormalities of the corpus callosum in schizophrenia: a diffusion tensor imaging study

OBJECTIVES: Diffusion tensor imaging (DTI), a technique capable of examining water diffusion in different tissues and the organisation of white matter tracts, was used to investigate the neuropathology of the corpus callosum in vivo in patients with schizophrenia. METHODS: Diffusion tensor imaging was performed in 20 schizophrenic patients and 25 healthy controls. Two complementary measures, mean diffusivity and fractional anisotropy, which are considered to be sensitive indices of axonal integrity, were obtained from regions of interest in the genu (anterior) and splenium (posterior) of the corpus callosum. RESULTS: Mean diffusivity was significantly increased and fractional anisotropy significantly reduced in the splenium but not the genu of the corpus callosum in the schizophrenic group compared with controls. There were no significant sex differences in the DTI measures for either the schizophrenic or control group. Clinical variables such as age, duration of illness, dose of antipsychotic medication, and schizophrenic symptoms did not predict the DTI changes in the schizophrenic patients. CONCLUSIONS: The presence of DTI changes in the splenium but not the genu of the corpus callosum suggests that there may be a focal disruption of commisural connectivity in schizophrenia. However, these findings do not exclude the possibility of abnormalities in other areas of the corpus callosum or other regions of white matter and further research using different methods of analysis may enable us to clarify this. Diffusion tensor imaging is a valuable tool in investigating the structure of white matter in schizophrenia.     

氢质子MR波谱对弥漫性轴索损伤的评估

景：目前在弥漫性轴索损伤的临床诊断和伤情评估上,CT和常规MRI的作用非常有限。 目的：验证氢质子MR波谱技术在弥漫性轴索损伤临床诊断及预后评估中的价值。 设计、时间及地点：前瞻性临床对照观察,于2002-10/2007-09在重庆医科大学附属第一医院神经外科及放射科完成。 对象：纳入63例颅脑损伤患者,根据MRI检查结果分为2组,弥漫性轴索损伤组27例,非弥漫性轴索损伤组36例;再利用单纯随机抽样法选择20名健康成年人作为正常对照。 方法：患者入院后,按常规进行治疗,一旦生命体征和意识情况允许,立即行包括液体衰减反转恢复序列在内的磁共振影像学检查,并在此同时行氢质子MR波谱检查,氢质子MR波谱检查数据进行后期工作站分析,并结合临床情况进行分析。 主要观察指标：胼胝体膝部、压部和基底核N-乙酰天冬氨酸/肌酸和磷酸肌酸、胆碱复合物/肌酸和磷酸肌酸、肌醇/肌酸和磷酸肌酸以及谷氨酸和谷氨酰胺/肌酸和磷酸肌酸等指标。 结果：与对照组和非弥漫性轴索损伤组相比,弥漫性轴索损伤组胼胝体膝部、压部和基底核出现N-乙酰天冬氨酸/肌酸和磷酸肌酸降低及胆碱复合物/肌酸和磷酸肌酸升高(P < 0.05~0.01),胼胝体膝部和压部出现肌醇/肌酸和磷酸肌酸及谷氨酰胺/肌酸和磷酸肌酸升高(P < 0.05)。与对照组相比,非弥漫性轴索损伤组出现胼胝体膝部胆碱复合物/肌酸和磷酸肌酸升高和压部N-乙酰天冬氨酸/肌酸和磷酸肌酸降低(P < 0.01),但变化程度比弥漫性轴索损伤组低。弥漫性轴索损伤组胼胝体膝部的胆碱复合物/肌酸和磷酸肌酸和伤后原发昏迷时间呈正相关(r=0.824,P < 0.01)。 结论：胼胝体膝部、压部和基底核各氢质子MR波谱指标可作为弥漫性轴索损伤有效的诊断指标。氢质子MR波谱中的胆碱复合物/肌酸和磷酸肌酸等指标可以很好地反映伤后组织学的改变,是临床伤情预测的灵敏指标。     

Corpus callosum size and neuropsychologic impairment in adolescents who were born preterm

Prematurity is associated with cerebral abnormalities that might account for poorer cognitive performance. The aim of our study was to investigate the correlations between corpus callosum reductions and neuropsychologic performance in adolescents who were born preterm. Twenty-five subjects born before 33 weeks' gestation were compared with 25 subjects born at term and of similar age, gender, and sociocultural status. All subjects underwent magnetic resonance imaging and neuropsychologic examinations. Premature subjects performed worse than controls in global cognitive functioning, verbal memory, and verbal fluency. Corpus callosum measurements showed a global reduction owing mainly to thinning in the splenium, posterior midbody, and genu. Corpus callosum size significantly correlated with gestational age, Wechsler Performance IQ, and memory performance. These results suggest that cerebral growth during infancy does not compensate for corpus callosum reduction and that this reduction reflects neuropsychologic deficit. The cognitive impairment can arise from the paucity of the complex interneuronal connections owing to fiber damage, particularly myelinated fibers.     

Behavior and corpus callosum morphology relationships in velocardiofacial syndrome (22q11.2 deletion syndrome)

Velocardiofacial syndrome (VCFS) is a neurodevelopmental disorder caused by a microdeletion on chromosome 22q11.2 that predisposes affected individuals to learning disabilities and psychiatric conditions. Previous research has indicated that compared with comparison children, children with VCFS have larger corpus callosal areas. Children with VCFS are often diagnosed with comorbid attention deficit hyperactivity disorder (ADHD), and previous research has indicated that children with ADHD often have smaller corpus callosal areas than controls. The present study investigated two hypotheses: children with VCFS would have larger callosal areas than controls, and children with VCFS+ADHD would have smaller callosal areas than children with VCFS. Corpus callosum area was obtained from the mid-sagittal slice and was assessed in children with VCFS (n=60) and age- and gender-matched control participants (n=52). Results indicated that all of the corpus callosum measures were significantly different between the two groups except for the genu. Across all measures, children with VCFS demonstrated a larger corpus callosum area. Within the VCFS sample, children with VCFS+ADHD (n=30) had smaller total callosal, splenium, and genu areas than children with VCFS alone. Although children with VCFS+ADHD had smaller total callosal areas than children with VCFS, relative to control participants, these children had larger total callosal and subregion areas except for the genu. In addition to other anatomic anomalies, corpus callosal abnormalities appear to be another variable to consider when analyzing brain/behavior relations in this population.     

No Differences in Corpus Callosum Size by Sex and Aging

To identify normal variations in the magnetic resonance imaging appearances of the corpus callosum with regard to sex and age, a prospective study was performed in 130 normal subjects. Callosal measurements were calculated by morphometric analysis. There were no significant sex differences in corpus callosum area or the callosal subregions. The absolute area did not decrease significantly with aging in normal males or females. However, age-related changes of callosal configuration were shown by a decrease in the ratio of the rostrum and genu to the splenium.     

Temporal characteristics of tract-specific anisotropy abnormalities in schizophrenia

White matter abnormalities have been detected using diffusion tensor imaging in a variety of locations in the brains of patients with schizophrenia. Studies that included first-episode patients report less severe or no abnormalities but more pronounced deficits in chronic patients. Here, we investigated these abnormalities in a very large group of patients with schizophrenia who had both large ranges in age and in duration of illness. A highly reproducible diffusion tensor imaging tractography technique was used to quantify the fractional anisotropy of the genu and splenium of the corpus callosum as well as the bilateral pyramidal tracts. We found a decline in fractional anisotropy that correlated with the duration of illness in the genu and splenium of the corpus callosum but not in the pyramidal tracts. The findings suggest that there are white matter tract-specific degenerative mechanisms that may be present at the point of illness onset and may progress throughout the illness.     

White matter loss in the splenium of the corpus callosum in a case of posterior cortical atrophy: a diffusion tensor imaging study

There have been several functional imaging studies using PET and SPECT to investigate posterior cortical atrophy (PCA). These studies have suggested dysfunction of corticocortical connections which is consistent with the occipitoparietal stream. However, there are no reports suggesting disturbance of the white matter that interconnects the temporal, parietal and occipital cortices. We measured fractional anisotropy (FA) in the genu and splenium of the corpus callosum and created color maps using diffusion tensor imaging (DTI), which is a relatively new MRI technique that allows visualization of the directionality of water diffusion, in a patient with PCA and compared these findings with those in 5 typical Alzheimer disease (AD) patients. The PCA patient was a 75-year-old man presenting with progressive complex visual disorder who satisfied the clinical diagnostic criteria for PCA. In 5 typical AD patients, the FA index in the splenium was higher than that in the genu; however, in the PCA patient, the FA index in the splenium was significantly lower than that in the genu. A DTI-based color map of the PCA patient showed reduction of anisotropy and fiber volume in the splenium. These findings suggest that the splenium of the corpus callosum secondarily degenerated due to neuronal degeneration of the temporal, parietal and occipital cortices and suggest that reduction of the FA in the splenium is one of the characteristics of PCA.     

Corpus callosum shape alterations in individuals prior to the onset of psychosis

Reductions in the size of the anterior callosum have been described for both first-episode schizophrenia-spectrum psychosis and established schizophrenia, but have not been examined in individuals at ultra-high risk for psychosis (UHR). We compared 100 UHR individuals (27 of whom later developed psychosis) with 38 age-matched control subjects on measures of size and shape of the corpus callosum to determine if changes previously demonstrated in first-episode and established schizophrenia are present in the pre-psychotic phase. Each individual's callosum was extracted from the mid-sagittal slice from T1-weighted magnetic resonance images, and total area, length and curvature of the callosum was compared using one-way ANOVA, and 39 regional thicknesses via a non-parametric permutation method to account for non-independence of adjacent measures. Total area, length and curvature did not differ between the groups. Compared to both the UHR-NP group and controls, the UHR-P group showed significant regional reductions in the region of the anterior genu of the callosum. The UHR-NP group did not differ from controls. Positive and negative symptoms did not affect regional thickness in either of the patient groups. Cox regression showed that mean anterior genu thickness was highly predictive of a transition to psychosis. Reductions in the thickness of the anterior callosum differentiate between high-risk individuals who transition to psychosis and those who do not, and is highly predictive of transition. These changes may reflect primary pathology of orbitofrontal and medial frontal cortex, or deficits in anterior interhemispheric myelination.