Serial MRI in a case of familial hemiplegic migraine.

We report MRI findings in a patient with familial hemiplegic migraine (FHM) with repeated episodes of hemiparesis. FHM is caused by a penetrant autosomal dominant genetic mutation; several mutations have been genotyped, involving brain-expressed ion channels. We found cerebral oedema, dilatation of intracerebral vessels and decreased water diffusion contralateral to the hemiparesis, not respecting vascular territories, with subsequent complete resolution of both clinical and imaging abnormalities. These results are thought to be consistent with an underlying primary neuronal pathology with secondary vascular effects, as opposed to the traditional, primarily vascular, model of migraine aetiology.