A young woman presenting with severe headache

A 20 year old woman with a history of migraine with visual aura in the form of both positive (fortification spectrum) and negative features was admitted to hospital because of unilateral pulsatile right sided headache of one day’s duration. The headache was associated with photophobia, intense nausea and vomiting, right sided facial and upper arm numbness, and a right sided temporal visual field defect. She described the headache as similar to her habitual migraines in character but “the worst ever.” On examination she was normotensive and her Glasgow coma scale was 15. On neurological examination the visual field defect was confirmed and she reported reduction in light touch over the right side of her face and right upper limb. With the exception of recurrent migraines at intervals of two to three months her medical history was unremarkable. She was not using any drugs on a regular basis apart from a progesterone contraceptive implant. She had no history of drug or alcohol misuse and did not smoke. Diffusion weighted magnetic resonance imaging (MRI) of the head was performed (fig 1⇓). ### 1 What is the abnormality seen on diffusion weighted MRI? #### Short answer The image shows an area of restricted diffusion—that is, an acute infarct in the left thalamus (fig 2⇓). Fig 2 Diffusion weighted magnetic resonance image of the head showing an area of increased signal (arrow) indicative of restricted diffusion that is in keeping with an acute infarct #### Long answer The area of increased signal in the left thalamus seen on the image is indicative of restricted diffusion and is in keeping with an acute infarct. The remainder of the brain parenchyma appears normal. T1 weighted scans …