A 65-year-old right-handed retired male firefighter presented following a fall. He had a 3-month history of scrotal paraesthesia that had insidiously evolved to bilateral leg weakness. Following hospital admission, he developed acute urinary retention requiring catheterisation.
He had a history of ulcerative colitis, which was well controlled with mesalazine. He was an ex-smoker and did not drink alcohol.
Cranial nerve and upper limb examinations were unremarkable. On lower limb examination, tone was normal. He had mild (Medical Research Council grade 4/5) bilateral and symmetrical weakness involving hip and knee flexion, and ankle dorsiflexion. There was a sensory level to T7. Joint position was impaired in the lower limbs, and vibration sense was absent below the xiphisternum. Knee and ankle jerks were absent, and plantar responses were mute.
Question 1. What is the most likely site of the lesion?
Although there were no obvious upper motor neurone signs, three clinical signs on lower limb…