A 70 year old man presented with a 30 minute history of throbbing left sided headache that woke him from sleep. He had no history of headache or recent head injury. He also described a four day history of breathlessness when climbing one flight of stairs.

He was taking tablets for type 2 diabetes mellitus, hypertension, and congestive cardiac failure. He did not smoke and drank seven units of alcohol a week.

The patient was alert and oriented, with a heart rate of 100 beats/minute and a blood pressure of 150/90 mm Hg. Respiratory rate was 16 breaths per minute, oxygen saturation was 98% on air, and his lungs were clear to auscultation. An early diastolic murmur was heard at the base of the heart. He had no temporal artery tenderness or neck stiffness.

Haemoglobin was 13.2 g/l; white blood cell count was 7×10⁹ cells/l; urea and electrolytes, liver function, and renal function were normal; and the erythrocyte sedimentation rate was 30 mm/hour (normal <20 mm/hour in men over 50). Electrocardiography showed sinus tachycardia. The results of chest radiography and computed tomography of the brain were normal.

He reported increasing headache with radiation down the cervical spine. At this time, blood pressure was 173/88 mm Hg in the right arm and 140/62 mm Hg in the left arm.