abnormal spinal cord morphology spina bifida occulta diastematomyelia diastomyelia csmith 2014-03-20T14:10:17Z a rare congenital anomaly that results in the splitting of the spinal cord in a longitudinal direction, usually at the level of the upper lumbar vertebra; this condition occurs in the presence of an osseous (bone), cartilaginous or fibrous septum in the central portion of the spinal canal which then produces a complete or incomplete sagittal division of the spinal cord into two hemicords, each half being surrounded by a dural sac; when the split does not reunite distally to the spur, the condition is referred to as a diplomyelia MP:0012710 MPheno.ontology