Diastematomyelia and the Klippel-Feil Syndrome
TWO hundred years ago Morgagni1 was unencumbered with the knowledge that the sac of a meningomyelocele consists of an open neural tube and, therefore, must represent failure of closure of the embryonal neural groove. From his observations, he naively concluded that these watery tumors of the vertebrae result from the pressure of fluid descending from the hydrocephalic head through the tube of the spine and pressing the bones asunder. The purpose of this presentation is to reexamine this hydromyelic theory of Morgagni in the light of present-day information, particularly in regard to diastematomyelia, a condition related to meningomyelocele in which the bones likewise are pressed asunder. The appearance of the divided spinal cord in diastematomyelia clearly indicates that this split develops not from failure of closure of the embryonal neural tube but because the lateral plates of this tube, following closure, have been pushed apart as a result of overdistention of its lumen.
Von Recklinghausen,2 in 1886, certainly was correct when he pointed out that the sac of the meningomyelocele is formed by an open portion of the neural tube. His assumption that this represents failure of closure has since been confirmed, albeit by investigators whose observations were based on this preconceived idea. It is now fitting that Morgagni’s disruption hypothesis receive similar consideration.
The Hydromyelic Theory
Immediately after its closure the neural tube of the normal embryo becomes distended because fluid forms within it more rapidly than it can escape through the semipermeable rhombic roof. As a result, the. . .