Review Question - QID 110003

A 65-year-old woman presents to the emergency department with a new-onset seizure. The patient was at home watching television when she suddenly began jerking her limbs and not responding according to her partner. The patient works as a gardener, is often dehydrated, but drinks large volumes of water to compensate for her work. She does not wear protective gear or sunscreen while working. She has smoked 1.5 packs of cigarettes per day for the past 40 years. She drinks liquor before bed every night. The patient has a medical history of hypertension and diabetes and recently lost 9 pounds. Her temperature is 98.0°F (36.7°C), blood pressure is 122/88 mmHg, pulse is 92/min, respirations are 14/min, and oxygen saturation is 99% on room air. Physical exam is within normal limits. Which of the following is the most likely underlying diagnosis in this patient?