Idiopathic spinal cord herniation: case report and review of the literature

Abstract

Background: Idiopathic spinal cord herniation (ISCH) is a rare cause of progressive myelopathy frequently present in Brown-Séquard syndrome. Preoperative diagnosis can be made with magnetic resonance imaging (MRI). Many surgical techniques have been applied by various authors and are usually reversible by surgical treatment.

Methods: Case report and review of the literature.

Findings: A 45-year-old woman with Brown-Séquard syndrome underwent thoracic MRI, which revealed transdural spinal cord herniation at T8 vertebral body level. During surgery the spinal cord was reduced and the ventral dural defect was restorated primarily and reinforced with a thin layer of subdermal fat. The dural defect was then closed with interrupted stitches.

Results: Although neurologic status improved postoperatively, postsurgical MRI demonstrated swelling and abnormal T2-signal intensity in the reduced spinal cord. Review of the English language literature revealed 100 ISCH cases.

Conclusions: ISCH is a rare clinical entity that should be considered in differential diagnosis of Brown-Séquard syndrome, especially among women in their fifth decade of life. Outcome for patients who initially had Brown-Séquard syndrome was significantly better than for patients who presented with spastic paralysis. Although progression of neurologic deficits can be very slow, reduction of the spinal cord and repair of the defect are crucial in stopping or reversing the deterioration.

Figure 1. Preoperative MRI. Sagittal (a) T1-weighted, (b) T2-weighted, and (c) fat-saturated T1-weighted images show ventral displacement of the spinal cord and enlarged dorsal subarachnoid space at T7-T8 (narrow arrow). (d) Axial T2-weighted image showing leftward anterior displacement of the spinal cord.

Figure 2. (a) Three-month postoperative dorsal MRI showing the spinal cord in an anatomical intradural location with reactive gliosis signal. (b) Axial MRI showing hyperintense parenchymal signal with reduced cord expansion.

Figure 3. Thirty-month postoperative (a) sagittal and (b) axial dorsal MRI T2-weighted scans demonstrate reactive gliosis signal due to preoperative period squeezing of spinal cord by the dural defect.

Figure 4. Distribution of reported idiopathic anterior thoracic spinal cord herniation according to disk level and vertebral body level.

Figure 5. Frequency of reported idiopathic anterior thoracic spinal cord herniation in the English literature from 1974 to the present.