The Experts below are selected from a list of 111 Experts worldwide ranked by ideXlab platform

Dachling Pang - One of the best experts on this subject based on the ideXlab platform.

  • split cord malformation part i a unified theory of embryogenesis for double spinal cord malformations
    Neurosurgery, 1992
    Co-Authors: Dachling Pang, Mark S Dias, Mamdouha Ahabbarmada
    Abstract:

    Much confusion still exists concerning the pathological definitions and clinical significance of double spinal cord malformations. Traditional terms used to describe the two main forms of these rare malformations, diastematomyelia and diplomyelia, add to the confusion by their inconsistent usage, ambiguities, and implications of their dissimilar embryogenesis. Based on the detailed radiographic and surgical findings of 39 cases of double cord malformations and the autopsy data on two other cases, this study endorses a new classification for double cord malformations and proposes a unified theory of embryogenesis for all their variant forms and features. The new classification recommends the term split cord malformation (SCM) for all double spinal cords. A Type I SCM consists of two hemicords, each contained within its own dural tube and separated by a dura-sheathed rigid osseocartilaginous median septum. A Type II SCM consists of two hemicords housed in a single dural tube separated by a nonrigid, fibrous median septum. These two essential features necessary for typing, the state of the dural tube and the nature of the median septum, do not ever overlap between the two main forms and can always be demonstrated by imaging studies so that accurate preoperative typing is always possible. All other associated structures in SCM such as paramedian nerve roots, myelomeningoceles manque, and centromedian vascular structures frequently do overlap between types and are not reliable typing criteria. The unified theory of embryogenesis proposes that all variant types of SCMs have a common embryogenetic mechanism. Basic to this mechanism is the formation of adhesions between ecto- and endoderm, leading to an accessory Neurenteric Canal around which condenses an endomesenchymal tract that bisects the developing notochord and causes formation of two hemineural plates. The altered state of the emerging split neural tube and the subsequent ontogenetic fates of the constituent components of the endomesenchymal tract ultimately determine the configuration and orientation of the hemicords, the nature of the median septum, the coexistence of various vascular, lipomatous, neural, and fibrous oddities within the median cleft, the high association with open myelodysplastic and cutaneous lesions, and the seemingly unlikely relationship with fore and midgut anomalies. The multiple facets of this theory are presented in increasing complexity against the background of known embryological facts and theories; the validity of each facet is tested by comparing structures and phenomena predicted by the facet with actual radiographic, surgical, and histopathological findings of these 41 cases of SCM.

  • Split Cord Malformation: Part I A Unified Theory of Embryogenesis for Double Spinal Cord Malformations
    Neurosurgery, 1992
    Co-Authors: Dachling Pang, Mark S Dias, Mamdouha Ahab-barmada
    Abstract:

    Much confusion still exists concerning the pathological definitions and clinical significance of double spinal cord malformations. Traditional terms used to describe the two main forms of these rare malformations, diastematomyelia and diplomyelia, add to the confusion by their inconsistent usage, ambiguities, and implications of their dissimilar embryogenesis. Based on the detailed radiographic and surgical findings of 39 cases of double cord malformations and the autopsy data on two other cases, this study endorses a new classification for double cord malformations and proposes a unified theory of embryogenesis for all their variant forms and features. The new classification recommends the term split cord malformation (SCM) for all double spinal cords. A Type I SCM consists of two hemicords, each contained within its own dural tube and separated by a dura-sheathed rigid osseocartilaginous median septum. A Type II SCM consists of two hemicords housed in a single dural tube separated by a nonrigid, fibrous median septum. These two essential features necessary for typing, the state of the dural tube and the nature of the median septum, do not ever overlap between the two main forms and can always be demonstrated by imaging studies so that accurate preoperative typing is always possible. All other associated structures in SCM such as paramedian nerve roots, myelomeningoceles manqué, and centromedian vascular structures frequently do overlap between types and are not reliable typing criteria. The unified theory of embryogenesis proposes that all variant types of SCMs have a common embryogenetic mechanism. Basic to this mechanism is the formation of adhesions between ecto- and endoderm, leading to an accessory Neurenteric Canal around which condenses an endomesenchymal tract that bisects the developing notochord and causes formation of two hemineural plates. The altered state of the emerging split neural tube and the subsequent ontogenetic fates of the constituent components of the endomesenchymal tract ultimately determine the configuration and orientation of the hemicords, the nature of the median septum, the coexistence of various vascular, lipomatous, neural, and fibrous oddities within the median cleft, the high association with open myelodysplastic and cutaneous lesions, and the seemingly unlikely relationship with fore and midgut anomalies. The multiple facets of this theory are presented in increasing complexity against the background of known embryological facts and theories; the validity of each facet is tested by comparing structures and phenomena predicted by the facet with actual radiographic, surgical, and histopathological findings of these 41 cases of SCM.

Mamdouha Ahab-barmada - One of the best experts on this subject based on the ideXlab platform.

  • Split Cord Malformation: Part I A Unified Theory of Embryogenesis for Double Spinal Cord Malformations
    Neurosurgery, 1992
    Co-Authors: Dachling Pang, Mark S Dias, Mamdouha Ahab-barmada
    Abstract:

    Much confusion still exists concerning the pathological definitions and clinical significance of double spinal cord malformations. Traditional terms used to describe the two main forms of these rare malformations, diastematomyelia and diplomyelia, add to the confusion by their inconsistent usage, ambiguities, and implications of their dissimilar embryogenesis. Based on the detailed radiographic and surgical findings of 39 cases of double cord malformations and the autopsy data on two other cases, this study endorses a new classification for double cord malformations and proposes a unified theory of embryogenesis for all their variant forms and features. The new classification recommends the term split cord malformation (SCM) for all double spinal cords. A Type I SCM consists of two hemicords, each contained within its own dural tube and separated by a dura-sheathed rigid osseocartilaginous median septum. A Type II SCM consists of two hemicords housed in a single dural tube separated by a nonrigid, fibrous median septum. These two essential features necessary for typing, the state of the dural tube and the nature of the median septum, do not ever overlap between the two main forms and can always be demonstrated by imaging studies so that accurate preoperative typing is always possible. All other associated structures in SCM such as paramedian nerve roots, myelomeningoceles manqué, and centromedian vascular structures frequently do overlap between types and are not reliable typing criteria. The unified theory of embryogenesis proposes that all variant types of SCMs have a common embryogenetic mechanism. Basic to this mechanism is the formation of adhesions between ecto- and endoderm, leading to an accessory Neurenteric Canal around which condenses an endomesenchymal tract that bisects the developing notochord and causes formation of two hemineural plates. The altered state of the emerging split neural tube and the subsequent ontogenetic fates of the constituent components of the endomesenchymal tract ultimately determine the configuration and orientation of the hemicords, the nature of the median septum, the coexistence of various vascular, lipomatous, neural, and fibrous oddities within the median cleft, the high association with open myelodysplastic and cutaneous lesions, and the seemingly unlikely relationship with fore and midgut anomalies. The multiple facets of this theory are presented in increasing complexity against the background of known embryological facts and theories; the validity of each facet is tested by comparing structures and phenomena predicted by the facet with actual radiographic, surgical, and histopathological findings of these 41 cases of SCM.

Mamdouha Ahabbarmada - One of the best experts on this subject based on the ideXlab platform.

  • split cord malformation part i a unified theory of embryogenesis for double spinal cord malformations
    Neurosurgery, 1992
    Co-Authors: Dachling Pang, Mark S Dias, Mamdouha Ahabbarmada
    Abstract:

    Much confusion still exists concerning the pathological definitions and clinical significance of double spinal cord malformations. Traditional terms used to describe the two main forms of these rare malformations, diastematomyelia and diplomyelia, add to the confusion by their inconsistent usage, ambiguities, and implications of their dissimilar embryogenesis. Based on the detailed radiographic and surgical findings of 39 cases of double cord malformations and the autopsy data on two other cases, this study endorses a new classification for double cord malformations and proposes a unified theory of embryogenesis for all their variant forms and features. The new classification recommends the term split cord malformation (SCM) for all double spinal cords. A Type I SCM consists of two hemicords, each contained within its own dural tube and separated by a dura-sheathed rigid osseocartilaginous median septum. A Type II SCM consists of two hemicords housed in a single dural tube separated by a nonrigid, fibrous median septum. These two essential features necessary for typing, the state of the dural tube and the nature of the median septum, do not ever overlap between the two main forms and can always be demonstrated by imaging studies so that accurate preoperative typing is always possible. All other associated structures in SCM such as paramedian nerve roots, myelomeningoceles manque, and centromedian vascular structures frequently do overlap between types and are not reliable typing criteria. The unified theory of embryogenesis proposes that all variant types of SCMs have a common embryogenetic mechanism. Basic to this mechanism is the formation of adhesions between ecto- and endoderm, leading to an accessory Neurenteric Canal around which condenses an endomesenchymal tract that bisects the developing notochord and causes formation of two hemineural plates. The altered state of the emerging split neural tube and the subsequent ontogenetic fates of the constituent components of the endomesenchymal tract ultimately determine the configuration and orientation of the hemicords, the nature of the median septum, the coexistence of various vascular, lipomatous, neural, and fibrous oddities within the median cleft, the high association with open myelodysplastic and cutaneous lesions, and the seemingly unlikely relationship with fore and midgut anomalies. The multiple facets of this theory are presented in increasing complexity against the background of known embryological facts and theories; the validity of each facet is tested by comparing structures and phenomena predicted by the facet with actual radiographic, surgical, and histopathological findings of these 41 cases of SCM.

Mark S Dias - One of the best experts on this subject based on the ideXlab platform.

  • split cord malformation part i a unified theory of embryogenesis for double spinal cord malformations
    Neurosurgery, 1992
    Co-Authors: Dachling Pang, Mark S Dias, Mamdouha Ahabbarmada
    Abstract:

    Much confusion still exists concerning the pathological definitions and clinical significance of double spinal cord malformations. Traditional terms used to describe the two main forms of these rare malformations, diastematomyelia and diplomyelia, add to the confusion by their inconsistent usage, ambiguities, and implications of their dissimilar embryogenesis. Based on the detailed radiographic and surgical findings of 39 cases of double cord malformations and the autopsy data on two other cases, this study endorses a new classification for double cord malformations and proposes a unified theory of embryogenesis for all their variant forms and features. The new classification recommends the term split cord malformation (SCM) for all double spinal cords. A Type I SCM consists of two hemicords, each contained within its own dural tube and separated by a dura-sheathed rigid osseocartilaginous median septum. A Type II SCM consists of two hemicords housed in a single dural tube separated by a nonrigid, fibrous median septum. These two essential features necessary for typing, the state of the dural tube and the nature of the median septum, do not ever overlap between the two main forms and can always be demonstrated by imaging studies so that accurate preoperative typing is always possible. All other associated structures in SCM such as paramedian nerve roots, myelomeningoceles manque, and centromedian vascular structures frequently do overlap between types and are not reliable typing criteria. The unified theory of embryogenesis proposes that all variant types of SCMs have a common embryogenetic mechanism. Basic to this mechanism is the formation of adhesions between ecto- and endoderm, leading to an accessory Neurenteric Canal around which condenses an endomesenchymal tract that bisects the developing notochord and causes formation of two hemineural plates. The altered state of the emerging split neural tube and the subsequent ontogenetic fates of the constituent components of the endomesenchymal tract ultimately determine the configuration and orientation of the hemicords, the nature of the median septum, the coexistence of various vascular, lipomatous, neural, and fibrous oddities within the median cleft, the high association with open myelodysplastic and cutaneous lesions, and the seemingly unlikely relationship with fore and midgut anomalies. The multiple facets of this theory are presented in increasing complexity against the background of known embryological facts and theories; the validity of each facet is tested by comparing structures and phenomena predicted by the facet with actual radiographic, surgical, and histopathological findings of these 41 cases of SCM.

  • Split Cord Malformation: Part I A Unified Theory of Embryogenesis for Double Spinal Cord Malformations
    Neurosurgery, 1992
    Co-Authors: Dachling Pang, Mark S Dias, Mamdouha Ahab-barmada
    Abstract:

    Much confusion still exists concerning the pathological definitions and clinical significance of double spinal cord malformations. Traditional terms used to describe the two main forms of these rare malformations, diastematomyelia and diplomyelia, add to the confusion by their inconsistent usage, ambiguities, and implications of their dissimilar embryogenesis. Based on the detailed radiographic and surgical findings of 39 cases of double cord malformations and the autopsy data on two other cases, this study endorses a new classification for double cord malformations and proposes a unified theory of embryogenesis for all their variant forms and features. The new classification recommends the term split cord malformation (SCM) for all double spinal cords. A Type I SCM consists of two hemicords, each contained within its own dural tube and separated by a dura-sheathed rigid osseocartilaginous median septum. A Type II SCM consists of two hemicords housed in a single dural tube separated by a nonrigid, fibrous median septum. These two essential features necessary for typing, the state of the dural tube and the nature of the median septum, do not ever overlap between the two main forms and can always be demonstrated by imaging studies so that accurate preoperative typing is always possible. All other associated structures in SCM such as paramedian nerve roots, myelomeningoceles manqué, and centromedian vascular structures frequently do overlap between types and are not reliable typing criteria. The unified theory of embryogenesis proposes that all variant types of SCMs have a common embryogenetic mechanism. Basic to this mechanism is the formation of adhesions between ecto- and endoderm, leading to an accessory Neurenteric Canal around which condenses an endomesenchymal tract that bisects the developing notochord and causes formation of two hemineural plates. The altered state of the emerging split neural tube and the subsequent ontogenetic fates of the constituent components of the endomesenchymal tract ultimately determine the configuration and orientation of the hemicords, the nature of the median septum, the coexistence of various vascular, lipomatous, neural, and fibrous oddities within the median cleft, the high association with open myelodysplastic and cutaneous lesions, and the seemingly unlikely relationship with fore and midgut anomalies. The multiple facets of this theory are presented in increasing complexity against the background of known embryological facts and theories; the validity of each facet is tested by comparing structures and phenomena predicted by the facet with actual radiographic, surgical, and histopathological findings of these 41 cases of SCM.

Christoph Viebahn - One of the best experts on this subject based on the ideXlab platform.

  • On the Enigma of the Human Neurenteric Canal.
    Cells tissues organs, 2018
    Co-Authors: Alexander Rulle, Nikoloz Tsikolia, Bernadette S. De Bakker, Charis Drummer, Rüdiger Behr, Christoph Viebahn
    Abstract:

    Existence and biomedical relevance of the Neurenteric Canal, a transient midline structure during early neurulation in the human embryo, have been controversially discussed for more than a century by embryologists and clinicians alike. In this study, the authors address the long-standing enigma by high-resolution histology and three-dimensional reconstruction using new and historic histological sections of 5 human 17- to 21-day-old embryos and of 2 marmoset monkey embryos of the species Callithrix jacchus at corresponding stages. The Neurenteric Canal presents itself as the classical vertical connection between the amniotic cavity and the yolk sac cavity and is lined (a) craniolaterally by a horseshoe-shaped "hinge of involuting notochordal cells" within Hensen's node and (b) caudally by the receding primitive streak epiblast dorsally and by notochordal plate epithelium ventrally, the latter of which covered the (longitudinal) notochordal Canal on its ventral side at the preceding stage. Furthermore, asymmetric parachordal nodal expression in Callithrix and morphological asymmetries within the nodes of the other specimens suggest an early non-cilium-dependent left-right symmetry breaking mode previously postulated for other mammals. We conclude that structure and position of the mammalian Neurenteric Canal support the notion of its homology with the reptilian blastopore as a whole and with a dorsal segment of the blastopore in amphibia. These new features of the Neurenteric Canal may further clarify the aetiology of foetal malformations such as junctional neurulation defects, neuroendodermal cysts, and the split notochord syndrome.