Brain MRI in our series. A (patient 1, at entry): hyperintense spots in axial FLAIR sequence involving periventicular and subcortical white matter. B, C (patient 1, one month later): axial FLAIR sequence showing multiple cortico-subcortical hyperintense lesions, some of which enhanced after gadolinium administration (axial T1: C). No meningeal enhancement is observed. D, E (patient 2, at entry): multiple nodular cortico-subcortical FLAIR hyperintense lesions involving fronto-temporal and insular regions. F (patient 2, three years later): axial FLAIR sequence revealing no abnormality. G (patient 3, three years after disease onset): axial FLAIR sequence showing a vast hyperintense cortico-subcortical temporo-occipital lesion. H, I (patient 3, two years after treatment onset with azathioprine): axial T1 revealing mild cortico-subcortical atrophy involving right temporal and occipital lobes with dilatation of posterior horn of right lateral ventricle. Magnification of right posterior atrophy by axial IR (I).