26th August 2024

A 24-year-old man presents to A&E with weakness.

A 24-year-old man presents to A&E with weakness. His flatmate, who attends with him, states that he complained of blurred vision and seeing double that morning and then started complaining of difficulty swallowing; his speech also became difficult to understand with slurring. He initially thought he must be drunk so left him to sleep it off. On returning later that day, he found him in a worse state, with difficulty moving his arms and an inability to raise his head off the bed. From reading his previous hospital notes, you see that he is a known IVDU (intravenous drug user) and is enrolled on a methadone program.

On examination, you note bilateral ptosis and impairment of eye movements, his facial muscles are likewise bilaterally weak and his speech is largely unintelligible now. He has flaccid weakness in both arms and in his neck. His observations are all normal, with no fever. You also note track marks on his arms and a badly infected wound in his right groin with fluctuance that feels like an underlying abscess.

What is the most likely cause?

Select the SINGLE most appropriate option from the list below. Select ONE option only.