The intermediate type split cord malformation: hypothesis and case report.

METHODS: A patient is described in which a complete osteofibrotic dorsally implanted septum was found in combination with a split cord malformation in a single dural tube. This case cannot be explained using the widely used theory as proposed by Pang et al. [Pang D, Dias MS, Ahab-Barmada M (1992) Split cord malformation, part I: A unified theory of embryogenesis for double spinal cord malformations. Neurosurgery 31:451-480] but must be regarded as a combination of type I and II split cord malformation. RESULTS: The authors state that all types of split cord malformation can be reduced to a single derailment during development, with various degrees of severity. CONCLUSIONS: The configuration of the malformation is determined by the way the median parts of the mesoderm come to development. Type I and II split cord malformation are not distinct entities.