Idiopathic ventral thoracic spinal cord herniation – A case report and literature review

While idiopathic ventral thoracic spinal cord herniation was first described by Wortzman et al. 4-decades ago, the pathophysiology remains a subject of significant controversy. Due to only approximately 260 cases having been described, the majority of which were managed operatively at the time of diagnosis, little is known about the natural history of the disease which confounds decision making regarding the optimal management strategy. What we do know is that epidemiological clustering occurs in middle-aged females, and that the disease has a predilection to occur in the high thoracic spine. Despite MRI imaging being the diagnostic modality of choice, misdiagnosis as a dorsal arachnoid cyst is common, and has been reported to occur in up to 45% of cases. Regarding management the attending neurosurgeon must decide whether a conservative approach with close surveillance is to be employed, bearing in mind an unknown risk of sudden neurological deterioration, or whether surgical intervention is to be employed. Regarding the actual surgical technique employed, additional considerations are whether a ventral or dorsal approach will be used, whether the defect will simply be widened to prevent spinal cord strangulation, or whether primary dural closure, or a dural patch, will be utilized. We describe an adult male patient who presented to our unit with insidiously progressive thoracic myelopathy, presenting as a Brown Sequard syndrome, secondary to idiopathic ventral thoracic spinal cord herniation. Utilizing intra-operative neurophysiological monitoring, which we advocate as a mandatory surgical adjunct in these cases, he was taken to the operating room where a laminectomy, midline dorsal linear durotomy, division of the dentate ligaments, adhesiolysis, reduction of the herniated spinal cord, dural patch closure of the ventral defect, and duropasty of the dorsal durotomy, was performed. By utilizing this combination of techniques, we report no early worsening of the patient's neurological deficit.