Extensive peripherally enhancing epidural collection is noted posterior to the theca from L5 up to L2. This results in thecal sac compression with severe compression of the cauda equina.
At L4/5 there facet joint effusions with adjacent bone marrow oedema particularly affecting the articular processes and pedicles of L4. This is associated with lower lumbar psoas and erector spinae muscular oedema (worse on the right) containing multiple small peripherally enhancing fluid collections.
Conclusion:
Bilateral L4/5 facet joint septic arthritis (right greater than left) - presumably communicating across the retrodural space of Okada - with associated epidural and muscular abscesses.