Tsai T, Bookstein FL, Levey E, Kinsman SL. Chiari-II malformation: a biometric analysis. European Journal of Pediatric Surgery. 2002 Dec;12 Suppl 1:S12-8.
INTRODUCTION: Chiari-II malformation is a complex set of anatomic abnormalities of the posterior fossa, brainstem, and cerebellum seen in myelomeningocele. Previous studies have tried to understand this condition and its clinical consequences by studying a few fixed anatomic landmarks as dependent variables and clinical symptoms as outcome variables. These studies have led to conflicting and limited results. As a first step towards a more comprehensive study of the structural-functional relationships in Chiari-II malformation, we undertook a biometric case-series analysis of a group of individuals with MMC, using both traditional methods to study size, and thin-plate spline methodology to study shape.
MATERIALS AND METHODS: The traditional analysis was a retrospective, randomly obtained case-series of 25 individuals with myelomeningocele and Chiari-II malformation. MRIs were digitized for biometric analysis of the component structures and compared to 25 controls. Landmarks on the digitized images were measured using Scion Image. Data were statistically analyzed using SPSS. The thin-plate spline analysis used a subset of these individuals (n = 14). Landmarks on digitized MRIs were identified and marked with TPSDig software. Landmark data was then imported into Splus to generate a series of shape variables. Statistical analysis using Splus was then undertaken. RESULTS: Traditional analysis revealed relationships between vermian herniation and pontomedullary junction position (p < 0.05) as well as between the height (and overall size) of the posterior fossa and degree of vermian herniation (p < 0.05). The degree of brainstem herniation/elongation did not correlate with the degree of vermian herniation. The shape analysis revealed that there is as much shape variability within the group of Chiari-II patients as there is between this group and unaffected controls. Thin-plate spline analysis shows that the position of the caudal-most aspect of the vermis is the point of greatest brain rearrangement; likewise, the opisthion is the point of greatest bony rearrangement. Partial least-squares analysis shows that in Chiari-II patients, a strong correlation (r = 0.821) exists between the extent to which the brain is warped (specifically, in regard to vermian descent) and the extent to which the bone is warped (specifically, in regard to the displacement of the opisthion) (p < 0.05).
CONCLUSION: Traditional biometric analysis of size confirms that the degree of vermian herniation and cervicomedullary junction herniation are independent variables in Chiari-II malformation. Posterior fossa size is an important factor in explaining the variability of vermian herniation. The relationship between IPN position and vermian herniation suggests the possibility of a common etiology. The phenomenon of cervicomedullary junction descent appears to be independent, suggesting a different etiology. Analysis of shape indicated that shape changes in bone and brain are related, and that the Chiari-II-associated abnormalities vary greatly in their degree of abnormality. The extreme morphological variability argues against the use of mean differences as a statistical technique in analyzing morphological abnormalities in the structures we investigated.
PMID: 12541208
Tuesday, July 31, 2007
Limbic tract anomalies in pediatric myelomeningocele and Chiari II malformation
Vachha B, Adams RC, Rollins NK. Limbic tract anomalies in pediatric myelomeningocele and Chiari II malformation: anatomic correlations with memory and learning--initial investigation. Radiology. 2006 Jul;240(1):194-202.
PURPOSE: To prospectively determine anomalies of limbic tracts and to describe the relationship between these anomalies, seen on diffusion-tensor magnetic resonance (MR) and fiber tract (FT) reconstruction images, and learning and memory in children with myelomeningocele (MM) and Chiari II malformation.
MATERIALS AND METHODS: The investigation was HIPAA compliant and approved by institutional review boards; informed consent was obtained. In seven male and six female patients (aged 6 months to 16 years) with MM and Chiari II malformation, diffusion-tensor imaging and FT reconstruction were performed. FT reconstruction was generated with fractional anisotropy continuous tracking algorithm and manually drawn regions of interest. Limbic tract abnormalities were assessed on FT reconstruction images by an experienced pediatric neuroradiologist blinded to results of cognitive testing. Nine patients met criteria for memory and learning testing by a trained cognitive neuroscientist blinded to MR results. Exact Wilcoxon rank sum test was used to compare performance with learning and memory tasks in two groups.
RESULTS: Eleven of 13 patients had defects within fornices and/or cingulum; three patients had aberrant fibers of cingulum. In nine patients, six had deficits in general memory; four, in learning; and four, in both. Atresia or hypoplasia of crura and body of fornices was noted in six patients with memory deficits and four patients with learning deficits. Five of six patients with memory deficits and three of four with learning deficits had hypoplasia or atresia of cingulum. Exact Wilcoxon rank sum test demonstrated significantly poorer performance for nonverbal immediate recall tasks in patients with anomalies of the fornix compared with those without (P = .04, exact two-tailed test).
CONCLUSION: Diffusion-tensor and FT reconstruction images revealed that limbic fiber abnormalities were common in patients with MM and Chiari II malformation. Nonverbal immediate recall task performance appeared to be related to abnormalities of the fornix.
PMID: 16793979
PURPOSE: To prospectively determine anomalies of limbic tracts and to describe the relationship between these anomalies, seen on diffusion-tensor magnetic resonance (MR) and fiber tract (FT) reconstruction images, and learning and memory in children with myelomeningocele (MM) and Chiari II malformation.
MATERIALS AND METHODS: The investigation was HIPAA compliant and approved by institutional review boards; informed consent was obtained. In seven male and six female patients (aged 6 months to 16 years) with MM and Chiari II malformation, diffusion-tensor imaging and FT reconstruction were performed. FT reconstruction was generated with fractional anisotropy continuous tracking algorithm and manually drawn regions of interest. Limbic tract abnormalities were assessed on FT reconstruction images by an experienced pediatric neuroradiologist blinded to results of cognitive testing. Nine patients met criteria for memory and learning testing by a trained cognitive neuroscientist blinded to MR results. Exact Wilcoxon rank sum test was used to compare performance with learning and memory tasks in two groups.
RESULTS: Eleven of 13 patients had defects within fornices and/or cingulum; three patients had aberrant fibers of cingulum. In nine patients, six had deficits in general memory; four, in learning; and four, in both. Atresia or hypoplasia of crura and body of fornices was noted in six patients with memory deficits and four patients with learning deficits. Five of six patients with memory deficits and three of four with learning deficits had hypoplasia or atresia of cingulum. Exact Wilcoxon rank sum test demonstrated significantly poorer performance for nonverbal immediate recall tasks in patients with anomalies of the fornix compared with those without (P = .04, exact two-tailed test).
CONCLUSION: Diffusion-tensor and FT reconstruction images revealed that limbic fiber abnormalities were common in patients with MM and Chiari II malformation. Nonverbal immediate recall task performance appeared to be related to abnormalities of the fornix.
PMID: 16793979
Saccades in children with spina bifida and Chiari type II malformation
Salman MS, Sharpe JA, Eizenman M, Lillakas L, To T, Westall C, Steinbach MJ, Dennis M. Saccades in children with spina bifida and Chiari type II malformation.
Neurology. 2005 Jun 28;64(12):2098-101.
BACKGROUND: Saccades are essential for optimal visual function. Chiari type II malformation (CII) is a congenital anomaly of the cerebellum and brainstem, associated with spina bifida.
OBJECTIVE: To investigate the effects of CII on saccades and correlate saccadic parameters with brain MRI measurements.
METHODS: Saccades were recorded in 21 participants with CII, aged 8 to 19, using an infrared eye tracker. Thirty-nine typically developing children served as controls. Participants made saccades to horizontal and vertical target steps. Nineteen participants with CII had MRI. Regression analyses were used to investigate the effects of spinal lesion level, number of shunt revisions, presence of nystagmus, and midsagittal MRI measurements on saccades.
RESULTS: Saccadic amplitude gains, asymptotic peak velocities, and latencies did not differ between the control and CII groups (p > 0.01). No significant differences were found between saccadic gains, asymptotic peak velocities or latencies, and spinal lesion level, number of shunt revisions, presence of nystagmus, or MRI measurements.
CONCLUSIONS: Saccades were normal in most participants with Chiari II malformation (CII). Neural coding of saccades is robust and is typically not affected by the anatomic deformity of CII.
PMID: 15985580
Neurology. 2005 Jun 28;64(12):2098-101.
BACKGROUND: Saccades are essential for optimal visual function. Chiari type II malformation (CII) is a congenital anomaly of the cerebellum and brainstem, associated with spina bifida.
OBJECTIVE: To investigate the effects of CII on saccades and correlate saccadic parameters with brain MRI measurements.
METHODS: Saccades were recorded in 21 participants with CII, aged 8 to 19, using an infrared eye tracker. Thirty-nine typically developing children served as controls. Participants made saccades to horizontal and vertical target steps. Nineteen participants with CII had MRI. Regression analyses were used to investigate the effects of spinal lesion level, number of shunt revisions, presence of nystagmus, and midsagittal MRI measurements on saccades.
RESULTS: Saccadic amplitude gains, asymptotic peak velocities, and latencies did not differ between the control and CII groups (p > 0.01). No significant differences were found between saccadic gains, asymptotic peak velocities or latencies, and spinal lesion level, number of shunt revisions, presence of nystagmus, or MRI measurements.
CONCLUSIONS: Saccades were normal in most participants with Chiari II malformation (CII). Neural coding of saccades is robust and is typically not affected by the anatomic deformity of CII.
PMID: 15985580
Degree of tectal beaking correlates to the presence of nystagmus in children with Chiari II malformation
Tubbs RS, Soleau S, Custis J, Wellons JC, Blount JP, Oakes WJ. Degree of tectal beaking correlates to the presence of nystagmus in children with Chiari II malformation. Child's Nervous System. 2004 Jul;20(7):459-61. Epub 2004 Apr 2.
INTRODUCTION: Tectal beaking is a common finding in children born with a myelomeningocele. Quantitation of the presence or absence of this finding correlated with normal or abnormal eye movements is lacking in the medical literature.
MATERIALS AND METHODS: We prospectively evaluated 50 children in our multidisciplinary spina bifida clinic. Each child was observed for the presence or absence of nystagmus at rest or with extraocular movement. Grades of nystagmus and severity of tectal beaking (Types I-III) on MRI were then correlated.
RESULTS: Overwhelmingly, children with greater dysmorphology of the mesencephalic tectum were most likely to have nystagmus. Higher grades of nystagmus were associated with Type III tectal beaking.
CONCLUSIONS: We have demonstrated that there is a correlation between the presence and severity of nystagmus and the severity of tectal beaking and have quantified this association in patients with the Chiari II malformation. This information may act as a guide in predicting which children with the Chiari II malformation will have significant nystagmus. These data may aid the clinician in the interpretation of oculomotor abnormalities in this cohort of patients.
PMID: 15060837
INTRODUCTION: Tectal beaking is a common finding in children born with a myelomeningocele. Quantitation of the presence or absence of this finding correlated with normal or abnormal eye movements is lacking in the medical literature.
MATERIALS AND METHODS: We prospectively evaluated 50 children in our multidisciplinary spina bifida clinic. Each child was observed for the presence or absence of nystagmus at rest or with extraocular movement. Grades of nystagmus and severity of tectal beaking (Types I-III) on MRI were then correlated.
RESULTS: Overwhelmingly, children with greater dysmorphology of the mesencephalic tectum were most likely to have nystagmus. Higher grades of nystagmus were associated with Type III tectal beaking.
CONCLUSIONS: We have demonstrated that there is a correlation between the presence and severity of nystagmus and the severity of tectal beaking and have quantified this association in patients with the Chiari II malformation. This information may act as a guide in predicting which children with the Chiari II malformation will have significant nystagmus. These data may aid the clinician in the interpretation of oculomotor abnormalities in this cohort of patients.
PMID: 15060837
Cerebral white matter and cognition in hydrocephalic children
Fletcher JM, Bohan TP, Brandt ME, Brookshire BL, Beaver SR, Francis DJ, Davidson KC, Thompson NM, Miner ME. Cerebral white matter and cognition in hydrocephalic children. Archives of Neurology. 1992 Aug;49(8):818-24.
Although children with hydrocephalus frequently show poor development of nonverbal cognitive skills relative to verbal skills, little is known about the neuropathologic correlates of these discrepancies. In this study, cerebral white-matter structures and lateral ventricles were measured from the magnetic resonance images of age-matched children with meningomyelocele, meningocele, and aqueductal stenosis and normal subjects. The volume of each lateral ventricle and the cross-sectional area of the corpus callosum and internal capsules were correlated with concurrent measures of verbal and nonverbal cognitive skills. The corpus callosum in the meningomyelocele and aqueductal stenosis groups was smaller. The lateral ventricles were larger, and the internal capsules were smaller, in all patient groups than in normal subjects. There were no differences in the size of the centra semiovale. Although verbal and nonverbal measures correlated positively with the size of the corpus callosum, the correlation was higher for nonverbal measures. Nonverbal measures correlated with the right, but not the left, lateral ventricle and with the area of the right and left internal capsules. Verbal measures correlated with the left, but not right, lateral ventricle and with the left, but not right, internal capsule. These results show a relationship between the corpus callosum and cognitive skills that is also influenced by hydrocephalus-related changes in the lateral ventricles and other cerebral white-matter tracts.
PMID: 1524514
Although children with hydrocephalus frequently show poor development of nonverbal cognitive skills relative to verbal skills, little is known about the neuropathologic correlates of these discrepancies. In this study, cerebral white-matter structures and lateral ventricles were measured from the magnetic resonance images of age-matched children with meningomyelocele, meningocele, and aqueductal stenosis and normal subjects. The volume of each lateral ventricle and the cross-sectional area of the corpus callosum and internal capsules were correlated with concurrent measures of verbal and nonverbal cognitive skills. The corpus callosum in the meningomyelocele and aqueductal stenosis groups was smaller. The lateral ventricles were larger, and the internal capsules were smaller, in all patient groups than in normal subjects. There were no differences in the size of the centra semiovale. Although verbal and nonverbal measures correlated positively with the size of the corpus callosum, the correlation was higher for nonverbal measures. Nonverbal measures correlated with the right, but not the left, lateral ventricle and with the area of the right and left internal capsules. Verbal measures correlated with the left, but not right, lateral ventricle and with the left, but not right, internal capsule. These results show a relationship between the corpus callosum and cognitive skills that is also influenced by hydrocephalus-related changes in the lateral ventricles and other cerebral white-matter tracts.
PMID: 1524514
Callosal anomalies in patients with spinal dysraphism: correlation of clinical and neuroimaging features with hemispheric abnormalities.
Kawamura T, Nishio S, Morioka T, Fukui K. Callosal anomalies in patients with spinal dysraphism: correlation of clinical and neuroimaging features with hemispheric abnormalities. Neurol Res. 2002 Jul;24(5):463-7.
Dysgenesis of the corpus callosum can occur in association with spinal dysraphic lesions. Clinical and neuroimaging features were reviewed in 23 patients (12 male, 11 female; mean age 11.3 years) with caudal spinal dysraphism (myeloschisis in eight, meningomyelocele in 10, and lumbosacral lipoma in five) to characterize types and degrees of callosal and other cerebral anomalies. T1- and T2-weighted magnetic resonance images were obtained, and the total midsagittal cross-sectional area of the corpus callosum was determined. The corpus callosum appeared normal in nine patients and was abnormal in 14. In five patients the corpus callosum was narrow, with all regions present; the cerebral hemispheres were hypoplastic. Two patients with dysgenesis of frontal, parietal, and occipital lobes had a small, partly agenetic corpus callosum. In the remaining seven patients the posterior third of the corpus callosum was absent or hypoplastic; six of them had ventriculomegaly that selectively affected the occipital horns (colpocephaly). All callosal anomalies were accompanied by hemispheric ones. This supports a disordered developmental relationship between the corpus callosum and the hemispheres as a cause. Spinal dysraphism can no longer be considered a single developmental abnormality, given the frequent association of other defects.
PMID: 12117315
Dysgenesis of the corpus callosum can occur in association with spinal dysraphic lesions. Clinical and neuroimaging features were reviewed in 23 patients (12 male, 11 female; mean age 11.3 years) with caudal spinal dysraphism (myeloschisis in eight, meningomyelocele in 10, and lumbosacral lipoma in five) to characterize types and degrees of callosal and other cerebral anomalies. T1- and T2-weighted magnetic resonance images were obtained, and the total midsagittal cross-sectional area of the corpus callosum was determined. The corpus callosum appeared normal in nine patients and was abnormal in 14. In five patients the corpus callosum was narrow, with all regions present; the cerebral hemispheres were hypoplastic. Two patients with dysgenesis of frontal, parietal, and occipital lobes had a small, partly agenetic corpus callosum. In the remaining seven patients the posterior third of the corpus callosum was absent or hypoplastic; six of them had ventriculomegaly that selectively affected the occipital horns (colpocephaly). All callosal anomalies were accompanied by hemispheric ones. This supports a disordered developmental relationship between the corpus callosum and the hemispheres as a cause. Spinal dysraphism can no longer be considered a single developmental abnormality, given the frequent association of other defects.
PMID: 12117315
Regional brain tissue composition in children with hydrocephalus. Relationships with cognitive development
Fletcher JM, McCauley SR, Brandt ME, Bohan TP, Kramer LA, Francis DJ, Thorstad K, Brookshire BL. Regional brain tissue composition in children with hydrocephalus. Relationships with cognitive development. Archives of Neurology. 1996 Jun;53(6):549-57.
OBJECTIVE: To determine whether children with shunted hydrocephalus show variations in regional brain tissue composition that relate to cognitive functions.
DESIGN: Nonequivalent control group.
PATIENTS AND METHODS: Magnetic resonance imaging (MRI) and cognitive skills assessments were obtained on 28 children, 6 to 9 years of age, with shunted hydrocephalus and 13 normal control subjects comparable in age, gender, ethnicity, and socioeconomic status. Three consecutive MRI slices below the vertex were segmented using a fuzzy clustering algorithm to separate pixels into gray matter, white matter, and cerebrospinal fluid (CSF) in quadrants representing left and right anterior and posterior brain regions. The cognitive skills assessments included the Wechsler Intelligence Scale for Children-Revised verbal and performance IQ scores, neuropsychological composites of language and visuospatial skills, a measure of visuomotor dexterity, and 2 measures of problem-solving abilities. The MRI data were analyzed in a group x tissue x hemisphere x region analysis of variance. Spearman rho correlations were computed within the hydrocephalus group between the MRI and cognitive measures.
RESULTS: Children with hydrocephalus showed reductions in overall gray matter percentages and corresponding increased CSF percentages that were more pronounced in posterior than anterior regions of both hemispheres. White matter percentages were reduced in children with hydrocephalus only in the left posterior quadrant. Correlations of posterior, but not anterior, CSF and gray matter percentages were significant with verbal and performance IQ scores and language, visuospatial, and visuomotor dexterity skills, but not with problem-solving abilities. Children with hydrocephalus who had proportionately greater posterior than anterior CSF percentages had significantly poorer visuomotor dexterity and visuospatial skills than did hydrocephalic children with proportionate CSF percentages.
CONCLUSION: Regional variations in brain tissue composition in children with shunted hydrocephalus correlate with a variety of cognitive and visuomotor functions.
PMID: 8660158
OBJECTIVE: To determine whether children with shunted hydrocephalus show variations in regional brain tissue composition that relate to cognitive functions.
DESIGN: Nonequivalent control group.
PATIENTS AND METHODS: Magnetic resonance imaging (MRI) and cognitive skills assessments were obtained on 28 children, 6 to 9 years of age, with shunted hydrocephalus and 13 normal control subjects comparable in age, gender, ethnicity, and socioeconomic status. Three consecutive MRI slices below the vertex were segmented using a fuzzy clustering algorithm to separate pixels into gray matter, white matter, and cerebrospinal fluid (CSF) in quadrants representing left and right anterior and posterior brain regions. The cognitive skills assessments included the Wechsler Intelligence Scale for Children-Revised verbal and performance IQ scores, neuropsychological composites of language and visuospatial skills, a measure of visuomotor dexterity, and 2 measures of problem-solving abilities. The MRI data were analyzed in a group x tissue x hemisphere x region analysis of variance. Spearman rho correlations were computed within the hydrocephalus group between the MRI and cognitive measures.
RESULTS: Children with hydrocephalus showed reductions in overall gray matter percentages and corresponding increased CSF percentages that were more pronounced in posterior than anterior regions of both hemispheres. White matter percentages were reduced in children with hydrocephalus only in the left posterior quadrant. Correlations of posterior, but not anterior, CSF and gray matter percentages were significant with verbal and performance IQ scores and language, visuospatial, and visuomotor dexterity skills, but not with problem-solving abilities. Children with hydrocephalus who had proportionately greater posterior than anterior CSF percentages had significantly poorer visuomotor dexterity and visuospatial skills than did hydrocephalic children with proportionate CSF percentages.
CONCLUSION: Regional variations in brain tissue composition in children with shunted hydrocephalus correlate with a variety of cognitive and visuomotor functions.
PMID: 8660158
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