A 21-year-old man with no medical history presented in 2007 with a generalised tonic-clonic seizure. Over the previous 2 months he had experienced intermittent episodes of left-sided paraesthesia. Examination was normal. MR scan of the brain showed right-sided temporal, parietal and occipital lobe abnormalities. Differential diagnoses included infection, inflammation and tumour. Vasculitic and thrombophilia screens were negative, serum ACE level normal. Cerebrospinal fluid (CSF) was unremarkable, with negative results for culture, cytology and oligoclonal bands. Echocardiogram and CT scan of the thorax, abdomen and pelvis were also normal. He started carbamazepine for focal …