Lung cancer Quiz: Ace Your Exams

A 62-year-old man presents to the emergency department after an episode of generalized tonic-clonic seizures. His partner, who witnessed the event, says the patient was sitting on the couch and suddenly started having rhythmic movement of the limbs with mouth foaming. The partner also reports that during the past 2 months, the patient has had a chronic cough, dyspnea, low mood, and difficulty remembering details. He seems to see “people that aren’t there,” including his mother, who passed away several years ago. The patient visited his primary physician recently due to paraesthesias in the arms and legs, which were attributed to his uncontrolled diabetes. Medical history is significant for hypothyroidism, diabetes mellitus type 2, and smoking 1 pack per day for 35 years. Temperature is 37.0°C (98.6°F), pulse is 80/min, and blood pressure is 125/85 mmHg. On physical examination, the patient is postictal and poorly responsive. This patient’s condition is most likely caused by which of the following?