Case 6

A 47-year-old male self presents to the emergency department with severe lower back pain radiating down both legs posteriorly. He reports that the pain came on suddenly three days ago after standing up from a chair. Today he is having difficulty mobilising and has noticed some difficulty passing urine, particularly when initiating a urinary stream.

On examination he is unable to plantarflex at the ankles and you are unable to obtain ankle jerk reflexes. Digital rectal examination demonstrates abnormal anal sphincter tone and the patients reports diminished sensation in the surrounding skin.

What is the diagnosis?

What investigation does this patient need?

What red flags do you need to look for on history and exam in any patient presenting to the emergency department with back pain?