A 75-year-old man presents to the Emergency department with weakness affecting both legs. The weakness had been preceded by a sudden onset of left sided hip pain, which had become intractable over the last four hours. He had also developed numbness over both legs to the level of the sternum. He had a past medical history of hypertension and ischaemic heart disease and took atenolol and Suscard buccal when required. He was a smoker of 10 cigarettes per day and drank a whiskey a night.
On examination, he appeared in distress. What is the likely cause for this patient’s symptoms?