Fig. 1. Pattern of epidural varicosity in operative field (schematic illustration). Veins dilated but do not compress nerve root (A; Type A). Veins dilated and located anterolaterally and compress nerve root (B; Type B). Veins dilated and encircled nerve root and compress it (C; Type C). Type N is normal anatomical structures with no varices exist (D). Venous varicosity (arrows).