Sacral agenesis: A case report with pathogenetic consideration

Abstract

A boy, born to a diabetic mother, showed external as well as internal malformations, such as cleft palate, deformation of the lower extremities, absence of the left kidney and contralateral compensatory hypertrophy, hydronephron and hydroureter. He died due to sepsis at the age of 2-months. At necropsy, the 0s sacrum was completely absent.The spinal canal was closed by osseous tissue at the level of the lowest lumbar vertebra. There was neither dorsal nor ventral dysraphism. The spinal cord segments were identifiable up to the L4/5 level and further spinal nerve roots formed the cauda equina. A duplication of the filum terminale was found that attached the cord to the bottom of the spinal canal. The caudal spinal cord was deformed, destructured and accompanied by astrocytic gliosis. The variety of the defect of lower spinal segments described in the literature (some cases included thoracic levels) and the existence of the fdum terminale in our case suggest that the spinal cord anomaly in sacral agenesis is neither a primary partial neural tube agenesis during the embryonal canalization phase nor is it an 'atrophy during ontogeny' (due to the 'no target-no development principle'), but is rather a destruction or due to other extraneural causes. In this context, a role of maternal diabetes may etiopathogenetically be speculated.