White matter microstructural abnormalities in children with spina bifida myelomeningocele and hydrocephalus: A diffusion tensor tractography study of the association pathways

Abstract

Purpose:To quantify microstructural abnormalities in the major association pathways of children affected by spina bifida myelomeningocele (SBM) and shunted hydrocephalus using whole-brain diffusion tensor imaging (DTI). Materials and Methods:The institutional review board approved this Health Insurance Portability and Accountability Act (HIPAA)-compliant study and written informed consent/assent were obtained prior to the study. The 69 participants included 38 children with SBM and shunted hydrocephalus (age mean Ϯ SD ϭ 12.30 Ϯ 2.10 years; 22 boys; 10 left-handed) and 31 age-and sex-matched normally-developing children (11.56 Ϯ 2.72 years; 15 boys, four left-handed). Diffusion tensor tractography (DTT) was performed to delineate and quantify bilaterally four major association pathways (arcuate, inferior longitudinal, inferior frontooccipital, and uncinate fasciculi). Results:The group with SBM did not exhibit the pattern of age-related decreases in the diffusivities observed in the controls. The transverse and axial diffusivities were significantly elevated in most of the white matter pathways of the participants with SBM. The fractional anisotropy (FA) was significantly lower in most of the association pathways. Many of the association pathways were not traceable in some participants with SBM compared to the controls at the selected FA thresholds. Conclusion:DTT revealed diffusion tensor characteristics of abnormal development (nonvisualization/poor visualization of tracts, 2 FA, 1 diffusivities), impairment in myelination (1 transverse diffusivity) as well as abnormalities in intrinsic axonal characteristics and extraaxonal/extracellular space (1 axial diffusivity) in the association pathways of the SBM children. The differences in the diffusion metrics observed in the children with SBM are suggestive of abnormal white matter development and persistent degeneration with increased age.

Anisotropic Diffusion Properties in Infants with Hydrocephalus: A Diffusion Tensor Imaging Study

“…Although Assaf et al 14 studied abnormal anisotropic diffusion properties in various WM regions before and after CSF shunt surgery, they did not include patients in early childhood, the common age of hydrocephalus presentation and treatment. In a similar fashion, in a recent DTI study by Hasan et al 15 of children with spina bifida and hydrocephalus, the average age of participants was 12.3 Ϯ 2.1 years, well beyond the usual age of diagnosis and treatment of childhood hydrocephalus.…”

“…Previously published reports have used DTI to examine the effects of hydrocephalus on WM in older children or in young adults. 14,15 In our study, the study population ranged from ages 1 day to 16 months at the time of the pretreatment MR imaging/DTI study. Thus, it fills a knowledge gap and provides a radiographic reflection of the understanding for the effects of hy Fig 3.…”

Diffusion-Weighted Imaging of the Cerebellum in the Fetus with Chiari II Malformation

“…Reduced FA and higher diffusivity have also been found in the major associative pathways of the supratentorial white matter tract in patients with Chiari II and are thought to reflect altered development and/or effects of chronic hydrocephalus on myelination, cell membrane integrity, and stretching of fibers. 9,10 Therefore, our findings may indeed reflect altered neuronal cell or fiber packing or organization in the context of abnormal cerebellar development. Our findings are also consistent in that the ADC values of the pons were not significantly different from those in healthy controls.…”

Neuropsychological Assessment of Adult Patients with Shunted Hydrocephalus

“…To corroborate this thesis, they performed diffusion tensor tractography to delineate and quantify bilaterally four major association pathways (arcuate, inferior longitudinal, inferior fronto-occipital, and uncinate fasciculi) of the patient with spina bifida meningomyelocele (SBM); and they showed that these patients have abnormal development, impairment in myelination as well as abnormalities in intrinsic axonal characteristics and extra-axonal/ extracellular space in their association pathways. At the end of this study they hypothesized that the differences in the diffusion metrics observed in the children with SBM are suggestive of abnormal white matter development and persistent degeneration with increased age 9,10) . On the other hand, there are few data on the adult hydrocephalus without SBM.…”