Fig. 1

MR image of the lumbosacral spinal roots and lumbar plexus. Gadolinium-enhanced T1-weighted imaging (T1WI) MRI five months after the onset of symptoms (A-F). On the coronal view, enlarged L3 and L4 spinal nerves and lumbar plexus with marked contrast enhancement (arrows) are visible on the left side (A-C). D-F show axial T2WI slices corresponding to the lines on B. Enlarged nerve roots were observed (D-F, arrowheads), and the L4 nerve root filled the intervertebral foramen (F). In the spinal canal, the affected nerves and normal-sized nerves coexisted. G-I show T2WI slices corresponding to the levels in D-F at ten months after onset. G-I show the enlarged cauda equina that was tangled and filled the spinal canal, and I shows the enlarged L4 nerve root (arrowheads)