• How did the headache start? Instantaneous onset? How long did it take to reach maximum intensity?
• Context of onset? With exertion? Orgasmic? On postural change? On waking?
• Still present? How long has it lasted?
• Syncope at onset?
• How severe? Worst headache ever?
• Distribution (unilateral, diffuse, localized)
• Nausea/vomiting? Photo/phonophobia? Pulsating quality? Inability to continue routine physical activities? (All associated with but not specific for migraine)
• Associated systemic, neurological or visual symptoms (e.g. syncope/presyncope, limb weakness, speech disturbance, blurring of vision, transient blindness, diplopia, scalp tenderness, jaw claudication, malaise, myalgia/stiffness, scotomata, fortification spectra). Did these precede or follow the headache?

Background

• Medication history and possible exposure to toxins
• Recent travel abroad?
• Immunosuppressed or known malignancy?
• Disorders associated with increased risk of aneurysmal subarachnoid haemorrhage: polycystic kidney disease, Ehlers-Danlos syndrome type IV, pseudoxanthoma elasticum, fibromuscular dysplasia, sickle cell disease, alfa-1 antitrypsin deficiency
• Family history of migraine or subarachnoid hemorrhage?

Examination

• Key observations: airway, respiratory rate, arterial oxygen saturation, heart rate, blood pressure, perfusion, consciousness level, temperature, blood glucose
• Neck stiffness (in both flexion and extension)?
• Focal neurological signs?
• Horner syndrome (partial ptosis and constricted pupil: if present, consider carotid artery dissection)?
• Visual acuity and fields
• Fundi (papilloedema or retinal haemorrhage?)
• Signs of dental, ENT or ophthalmic disease?
• Temporal artery tenderness or loss of pulsation?