Fig. 8. Method for grading cases without a visible extraforaminal nerve root. A. The extraforaminal nerve root on the right side is not visible on the T2-weighted axial magnetic resonance image (yellow dotted-circle). B. The distance (a) between the posterior margin of the vertebral artery (red dotted-circle) and the anterior margin of the superior articular process (white dotted-line) or the width (b) of the contralateral extraforaminal nerve root can be used as reference.
