Review Question - QID 213831

A 34-year-old man presents to his primary care physician with a 1-month history of pain and numbness in his right arm. He says that he recently started trying to exercise after being sedentary for most of his life and noticed that he is significantly weaker with his right hand compared with his left. After several minutes of exercise, his right hand becomes numb, and his right arm begins to have painful spasms. He denies any recent trauma or other symptoms such as fever or cough. His past medical history is significant for diabetes, and he has been smoking 2 packs per day for the last 20 years. He has gained 5 pounds since the last visit. Physical exam reveals atrophy of his palmar interosseous muscles as well as decreased sensation on the medial aspect of his hand and forearm. Which of the following is the most likely cause of this patient's symptoms?