Pathophysiology and Grading of the Ventral Displacement of Dorsal Spinal Cord Spectrum

Abstract

Study design: A retrospective study of the ventral displacement of dorsal spinal cord (VDDSC) spectrum pathophysiology and grading.

Purpose: This study aimed at examining the pathophysiology of VDDSC between D3 and D7, using magnetic resonance imaging (MRI) correlation and severity grading.

Overview of literature: The pathologies that lead to VDDSC were previously discussed in various articles. We attempted to group these pathological conditions under a single spectrum, and grade them according to their severity.

Methods: We reviewed the MRI images of the dorsal spines of 1,350 patients over a period of 4 years (February 2013-February 2017); all MRI images were analyzed by two experienced radiologists.

Results: Of the 1,350 patients, 28 exhibited VDDSC between D3 and D7. Additional findings included ventral transdural herniation of the spinal cord (n=10), anterior spinal cord adhesion (n=7), arachnoid web (n=6), and arachnoid cyst (n=5).

Conclusions: We grouped the pathologies that lead to VDDSC at the thoracic level into a single spectrum of varying severity and graded VDDSC, from mild to severe.

Keywords: Adhesion; Arachnoid cyst; Arachnoid web; Dorsal spinal cord; Ventral displacement.

Fig. 1. (A, B) Schematic diagram of sagittal and axial sections of the dorsal spine showing normal anterior position of spinal cord (arrow) due to dorsal kyphosis. Hoffman ligament (curved arrow), denticulate ligament (double arrow), and septum posticum (open arrow).

Fig. 2. (A, B) Schematic diagram of sagittal and axial sections of dorsal spine showing mild ventral displacement due to thickening of the septum posticum (straight arrow) with scalpel sign-arachnoid web. (C) Magnetic resonance imaging T2 sagittal section shows anterior cord displacement with scalpel sign at the D4 vertebral level (arrow).

Fig. 3. (A, B) Schematic diagram of sagittal and axial sections of the dorsal spine showing moderate ventral displacement due to arachnoid cyst formation (arrow). (C, D) Magnetic resonance imaging T2 sagittal and axial sections of a 38-year-old male patient with arachnoid cyst (straight arrow) causing cord compression with smooth ventral displacement at the D3 and D4 vertebral level.

Fig. 4. (A, B) Schematic diagram and (C, D) magnetic resonance imaging spine T2 weighted sagittal and axial sections of the dorsal spine show severe ventral displacement of dorsal spinal cord due to adhesion (straight arrow) to the ventral dura with a widened posterior subarachnoid space, without cord herniation.

Fig. 5. (A, B) Schematic diagram shows (C, D) magnetic resonance imaging spine T2 weighted sagittal and axial sections of dorsal spine with severe asymmetric ventral displacement of the cord with herniation (straight arrow).

Fig. 6. (A–C) Schematic diagram showing ventral displacement of dorsal spinal cord in cord adhesions: mechanisms showing ventral displacement of the spinal cord due to arachnoid adhesions (straight arrow), lax denticulate ligament (double arrow), and septum posticum (open arrow), respectively.

Fig. 7. (A, B) Mechanism of an anterior dural tear. The arrow indicates turbulent cerebrospinal fluid flow at the dural attachment site of the spinal cord. The double arrow indicates repeated flexion-extension movements of the spinal cord.