Transdural herniation of the spinal cord is thought to be previously extremely rare and very often misdiagnosed. Possible reasons may be iatrogenic and traumatic or in about one third of cases it may be unknown, where the probable origin might be a congenital dural defect. The pathology may show characteristic and misleading MR patterns of the thoracic spine, emphasising the importance of these patterns. This anomaly can lead to progressive Brown-Sequard syndrome. Surgical intervention, consisting the repair of the dural defect may result in improvement or even complete regression of the neurologic deficits.