Mr. J.B. is a 40-year-old machinist who has generally been in good health with the exception of hyperlipidemia treated with atorvastatin 20 mg daily. He presented with a two-week history of right back pain of about two weeks duration. This had been preceded by right leg pain, and he was now also noticing discomfort in the left leg as well. He denied acute trauma or injury, though he spent a lot of time standing on cement floors at work. The pain persisted when the patient was recumbent.

Physical exam revealed normal straight-leg raising and normal strength and sensation in the lower limbs but with some diminution in the right ankle jerk (AJ) reflex. Lumbar spine films were unremarkable, as were CBC and ESR. Physiotherapy and an NSAID were prescribed and on J.B.’s return 10 days later he reported “50% improvement” in pain levels. It was noted, however, that he’d developed some decreased sensation in the right lateral foot and the AJ reflex remained diminished.

Several weeks later J.B. was reassessed and found to have diminished strength in both lower limbs with bilaterally reduced AJ reflexes and symmetrically very brisk knee jerk reflexes. He also stated that a hot bath seemed to aggravate his symptoms. An urgent orthopedic consultation was arranged and a lumbar myelogram was performed, which was found to be normal. EMG studies were abnormal and non-specific, though suggestive of “multiple lumbosacral radiculopathies.”

JB’s weakness progressed rapidly and it was decided to obtain an MRI. What did this investigation show?