医師国家試験 第117回 問277

A35-year-old man complained of a sudden onset of severe headache. For the past two weeks, he woke up around 3:00 a.m. due to soreness behind the left eye. His pain continued for about an hour. Today, he visited the emergency department at 5:30 a.m. His consciousness was clear, but he appeared restless. His body temperature was 36.4 °C. Pulse rate was 84/min. Blood pressure was 136/80mmHg. Conjunctival hyperemia and tearing of the left eye were observed. There were no meningeal signs. MRI and MRA of the head showed no abnormalities. What is the most likely diagnosis?