MR visualization and clinical significance of the anterior longitudinal epidural venous plexus in cervical extra-axial lesions.

A thin band of intermediate signal intensity behind the cervical vertebral bodies, demonstrated on sagittal MR images, was attributed to the anterior longitudinal epidural venous (AEVP). Percentage visualization and clinical significance of this structure were evaluated in extra-axial lesions of the spinal cord. In review of 50 normal controls, the percentage visualization of this structure at each cervical vertebral level was 25.5% on T1 weighted sagittal SE images, while that of T2 or proton density weighted SE images was 26.0%. AEVP was demonstrated by sagittal MRI in 29 of 128 extra-axial lesions of the cervical cord (22.7%), including cervical spondylosis, ossification of the posterior longitudinal ligament (PLL), herniated disk and spondylosis at a single level. AEVP in these conditions was often thickened compared with normal controls, probably due to venous engorgement and contribution of the dura mater and PLL. Posterior displacement of this structure or "lifted band appearance" indicated herniated disk or posteriorly protruding osteophyte, demonstrating true anteroposterior diameter of the spinal canal. Demonstration of AEVP on sagittal MRI was important in the diagnosis of extra-axial lesions of the cervical cord.