Figure 2.

(A) Selective venography of the azygous vein in a control case (HAV-C) (a) and in MS cases (b, c, d). (a) Normal azygous vein, azygous arch and descending trunk (AZY); H, heart; SVC, superior vena cava. (b) Twisting (arrow) just below the azygous arch. (c) Membranous obstruction (arrow) at the junction of the AZY with the SVC. (d) Septum (arrow) of the proximal AZY. (B) Selective venography of the internal jugular vein (IJV) in a control case (HAV-C) (e) and in multiple sclerosis (MS) cases (f, g, h). (e) Normal right IJV (IJVr) with normal outflow and without stenosis after injection. (f) Annulus of the left jugular vein, JVl (IJVl, arrow) at the junction with the brachiocephalic trunk (BCT). (g) Closed stenosis of the IJVl (arrow) with reflux after injection and collateral circles (CC) depicted by small arrows. (h) Annulus of the IJVr (arrow) with reflux and activation of numerous cervical collateral circles involving the thyroid veins (CC); one of them re-enters the SVC. (C) Selective venography of the lumbar veins in a control case (HAV-C) (i) and in MS cases (j, k, l). (i) Selective venography of the ascending lumbar vein (LV) from the iliac vein (IV): normal appearance with characteristic hexagonal shape of the intrarachidian plexus draining outward into the LV and upward to the azygous system. (j, k, l) Dramatic bare venous lumbar tree in MS cases with combination of agenesia and atresia. This picture is further associated with multilevel stenosis of the azygous system configuring the chronic cerebrospinal venous insufficiency type D pattern.