A 29-year-old right-handed man reports a three-day history of upper and lower limb weakness, moreso in the upper limbs, worse on the left side. He denies pain and numbness. There is no history of trauma, and no bowel or bladder incontinence. • Prior to continuing, please develop a differential and list each diagnosis in order of likelihood. • Is there any additional information from the clinical history that might be helpful in clarifying your differential list or changing its order of priority?