Animation: Post-discectomy radiculitis.
Two fascicles in the right S1 root are hyperintense as they descend from the root sleeve (A) and traverse the sacrum (B,C, D & E arrows).
The contralateral S1 root is normal in appearance. The patient experienced focal pain in the calf despite relief of other symptoms by microdiscectomy. There was no recurrent disc.
The symptoms resolved with a short course of dexamethasone.