Figure 4.

Selective venography and MRI in a clinically defined multiple sclerosis case with chronic cerebrospinal venous insufficiency pattern D. Left: selective venography showing membranous obstruction of the outlet of the azygous vein (AZY) combined with atresia of the descending azygous vein (arrow). Due to multilevel obstruction of the azygous system, the vertebral plexus is dilated below the atresia, and the blood is drained through intrarachidian collateral circles (IRC) in an upward direction. Top right: sagittal T1 weighted imaging after gadolinium injection of the same case, showing typical multiple sclerosis lesions of the spinal cord. The enhanced gadolinium image shows intrarachidian venous plexuses in the form of small spots. Bottom right: axial merge T2 of the same patient at the cervical level with dilated extrarachidian venous plexuses. SVC, superior vena cava.