Structural Connectivity Analysis in Children with Segmental Callosal Agenesis

Severino, Mariasavina; Tortora, Domenico; Toselli, Benedetta; Uccella, Sarà; Traverso, Maria Esther Duran; Morana, Giovanni; Capra, Valeria; Veneselli, Edvige; Fato, Marco; Rossi, Andrea

doi:10.3174/ajnr.a5043

Cited by 14 publications

(4 citation statements)

References 26 publications

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“…In humans affected by CCA, remodeled cingulum bundles have been comprehensively described using DTI tractography ( 4 , 5 , 16 ). Among humans affected by CCA, compensatory neuroplasticity of the ipsilateral hemispheric axonal tracts is proposed as the mechanism responsible for remodeling of the cingulum and a variable degree of Probst bundle development is evident among patients ( 17 ). This aspect remains uncertain for canine CCA, as the present report is based on a single case; however, this presents an opportunity to prospectively screen for the presence and characteristics of Probst bundles using DTI.…”

Section: Discussionmentioning

confidence: 99%

Presence of Probst Bundles Indicate White Matter Remodeling in a Dog With Corpus Callosum Hypoplasia and Dysplasia

2018

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Corpus callosum abnormalities (CCA) rarely occur in dogs and are related to hypo/adypsic hypernatremia and seizures. Hypoplasia and dysplasia of the corpus callosum (CC) with concomitant lobar holoprosencephaly is the most common variant. It is currently uncertain using conventional MRI if canine CCA reflects the failure of commissural fibers to develop or the failure of the commissural fibers to cross hemispheres. Diffusion tensor imaging was performed in a 4-year-old Staffordshire mix breed dog with CCA and an age-matched healthy Beagle. In comparison to the control dog, CC tractography of the affected dog depicted only axonal tracts corresponding to the temporal CC fibers. The cingulum bundles appeared supernumerary with unorganized architecture, extending into the ipsilateral cerebral cortex, and therefore strongly suggested homology to Probst bundles reported in humans with CCA. The presence of Probst bundles in canine CCA could represent compensatory neuroplasticity-mediated networking and may contribute the fair prognosis reported in affected dogs.

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Section: Discussionmentioning

confidence: 99%

Presence of Probst Bundles Indicate White Matter Remodeling in a Dog With Corpus Callosum Hypoplasia and Dysplasia

2018

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“…Connectome and MRI analysis of individuals with segACC has shed light on the various paths axons take when they can not, or do not, properly decussate. Perhaps the most commonly observed surrogate pathway found in segACC would be the formation of Probst bundles - where axons run para-sagittally along the interhemispheric fissure instead of decussating midline [ 3 ]. Our case lacks the widely spaced frontal horns, and dilated trigones usually seen with the formation of Probst bundles.…”

Section: Discussionmentioning

confidence: 99%

“…This theory has fallen out of favor with support that callosal axons cross the midline through an area of secondary interhemispheric fusion, and that the cavum septum pellucidum is the portion of the interhemispheric fissure that becomes enclosed by the development of the surrounding corpus callosum [ 1 , 2 ]. Support for the latter theory has thus far been predicated upon: 1) Gross examination of anatomic specimens at various stages of development; 2) Magnetic resonance imaging (MRI), as in our case, reveals segmental agenesis between the genu and splenium, suggesting that the midline crossing bed of the developing corpus callosum (week 12 and 13) occurs after the anterior and hippocampal commissures cross (weeks 10 and 11 respectively) [ 1 , 2 ]; 3) Connectivity analysis with diffusion tensor imaging and tractography has revealed that cingulate cortex axonal projections from multiple distinct loci decussate the commissural plate, giving rise to the anterior and hippocampal commissures, which later fuse to form the corpus callosum [ 1 , 3 ]. Although the corpus callosum appears to grow in a rosto-caudal fashion, the commissure actually grows in conjunction with the hemispheres, with the genu developing prenatally, and the splenium mostly growing postnatally [ 2 ].…”

Section: Introductionmentioning

confidence: 99%

Segmental Agenesis of the Corpus Callosum With Pituitary Hypoplasia

Haver,

Junewick

2024

Cureus

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We report a 3-year-old male with findings of segmental agenesis of the corpus callosum, pituitary hypoplasia, and Chiari I malformation. The patient was born at 33 weeks and spent five weeks in the NICU for hypoglycemia, hypotension, and dyspnea. In infancy, the patient passed an adrenocorticotropic hormone stimulation test, while cortisol, growth hormone, and insulin-like growth factor levels were within reference range. Following height and weight percentile regression the patient underwent arginine and clonidine stimulation testing at 3 years of age, prompting pituitary evaluation via MRI. The results provided exemplary neuroimaging of segmental callosal agenesis, in which the genu and splenium form despite the absence of the callosal body. This finding adds support to a newer theory of embryological callosal development where progression does not occur linearly in the rosto-caudal direction.

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“…Callosal malformations vary extensively in their presentation, from hypoplasic (reduced midsagittal CC area) and partial (usually with a rostral CC remnant in humans and caudal in mice) formations to complete agenesis ( Tovar-Moll et al, 2006 ). Regardless of the degree of callosal malformations, reorganization of the CCD brain can generate new aberrant white matter fiber bundles ( Probst, 1901 ; Tovar-Moll et al, 2006 ; Paul et al, 2007 ; Kasprian et al, 2013 ; Severino et al, 2017 ; Edwards et al, 2020 ; Szczupak et al, 2020a ), leading to widespread structural ( Owen et al, 2013b ; Jakab et al, 2015 ; Siffredi et al, 2020 ; Szczupak et al, 2021b ), and functional ( Owen et al, 2013a ; Tovar-Moll et al, 2014 ; Lazarev et al, 2016 ; Monteiro et al, 2019 ; Szczupak et al, 2020b , 2021b ) changes affecting the entire brain. For example, hypoplasic CCD subjects and mouse models have an atypical structural brain connectivity profile that is substantially different from that of healthy subjects ( Owen et al, 2013b ; Edwards et al, 2020 ; Szczupak et al, 2020a , 2021b ; Siffredi et al, 2021 ).…”

Section: Introductionmentioning

confidence: 99%

Heterotopic connectivity of callosal dysgenesis in mice and humans

et al. 2023

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The corpus callosum (CC), the largest brain commissure and the primary white matter pathway for interhemispheric cortical connectivity, was traditionally viewed as a predominantly homotopic structure, connecting mirror areas of the cortex. However, new studies verified that most callosal commissural fibers are heterotopic. Recently, we reported that ~75% of the callosal connections in the brains of mice, marmosets, and humans are heterotopic, having an essential role in determining the global properties of brain networks. In the present study, we leveraged high-resolution diffusion-weighted imaging and graph network modeling to investigate the relationship between heterotopic and homotopic callosal fibers in human subjects and in a spontaneous mouse model of Corpus Callosum Dysgenesis (CCD), a congenital developmental CC malformation that leads to widespread whole-brain reorganization. Our results show that the CCD brain is more heterotopic than the normotypical brain, with both mouse and human CCD subjects displaying highly variable heterotopicity maps. CCD mice have a clear heterotopicity cluster in the anterior CC, while hypoplasic humans have strongly variable patterns. Graph network-based connectivity profile showed a direct impact of heterotopic connections on CCD brains altering several network-based statistics. Our collective results show that CCD directly alters heterotopic connections and brain connectivity.

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Structural Connectivity Analysis in Children with Segmental Callosal Agenesis

Cited by 14 publications

References 26 publications

Presence of Probst Bundles Indicate White Matter Remodeling in a Dog With Corpus Callosum Hypoplasia and Dysplasia

Presence of Probst Bundles Indicate White Matter Remodeling in a Dog With Corpus Callosum Hypoplasia and Dysplasia

Segmental Agenesis of the Corpus Callosum With Pituitary Hypoplasia

Heterotopic connectivity of callosal dysgenesis in mice and humans

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