Sudden Onset Occipital Headache as a Presenting Feature of Ischaemic Stroke

Headache is an uncommon presenting feature of ischaemic stroke, and when it occurs, it is usually moderate and sustained rather than sudden and self-limiting. We describe the case of a 56-year-old man who presented after a single, abrupt, extremely intense occipital headache that reached 10/10 and resolved completely within about 30 seconds. The neurological examination on arrival was normal, including a National Institutes of Health Stroke Scale (NIHSS) score of 0. The patient separately reported a subtle change in vision on the left side, and formal perimetry showed a left superior homonymous quadrantanopia that had not been apparent on bedside confrontation testing. Computed tomography (CT) of the head was unremarkable with no acute changes, and magnetic resonance imaging (MRI) confirmed a 3.5 cm acute infarct in the right occipital lobe, with incidental small chronic infarcts in the left cerebellum and right caudate head suggesting previous clinically silent events. There were no conventional vascular risk factors apart from an untreated dyslipidaemia, and the patient had sustained a minor head injury a week earlier. An extended thrombophilia screen revealed an elevated anti-β2 glycoprotein I antibody, with confirmatory testing pending. This case is a reminder that a brief, isolated, thunderclap-type occipital headache with a normal examination can be the only warning of an occipital infarct, that the diagnosis can hinge on a patient-reported visual symptom and formal visual field testing, and that early MRI is needed because CT is insensitive to early posterior infarction.