Question category: Neurology
A 67 year old male presents to her GP with two months of back pain. He is given analgesia however one week later he is admitted to A+E with bilateral leg weakness and urinary retention. He has recently lost a significant amount of weight. He is a heavy smoker. On examination his arms are hyperreflexic. He has 4/5 in hip and knee flexors. He has upgoing plantars and is hyperreflexic and has reduced sensation throughout all dermatomes of the lower limbs. He has normal anal sphincter tone, enlarged prostate and on passing a catheter for his retention he has reduced sensation. What investigation would you order?