A 59-year-old man presents to the outpatient neurology clinic with 9 months of progressive weakness in his bilateral lower extremities. He denies any associated pain, stating it started in his legs, worse on the left, then 2 weeks later he noticed weakness in his shoulders. He reports since then it has become progressively more difficult to stand from a chair, ascend stairs, lift his arms over his head, and, most recently, open jars. He claims his arms and legs seem smaller than they used to. His biggest concern is his difficulty using his hands, with which he now has difficulty carrying or holding objects such as grocery bags. He denies any sensory changes, trauma, or other neurological history.