pattern that likely corresponds to inflamed cerebral vessels and perivascular regions.

Case presentation
=================

A 47-year-old Caucasian man initially presented with a two-month history of progressive bilateral hand tremor, difficulty walking, behavioral changes and headache. On examination he was afebrile, with poor memory recall, bilateral action and postural tremor, diffuse hyperreflexia with the presence of Babinski signs bilaterally, frontal release signs, bilateral dysmetria and marked truncal ataxia resulting in an inability to walk. His medical history included hypertension, anxiety disorder and tobacco use. Medications included citalopram and lisinopril.

T2-weighted fluid attenuated inversion recovery (FLAIR) brain MRI revealed diffuse, symmetrical, increased intensity throughout the white matter in his centrum semiovale and corona radiata (Figure [1](#F1){ref-type="fig"}A) concurrent with bilateral linear enhancement in a radial distribution on the gadolinium-contrasted study (Figure [1](#F1){ref-type="fig"}B,C). The subcortical 'U' fibers of his white and grey matter were spared. No abnormalities were noted in his cerebellum and corpus callosum. Magnetic resonance spectroscopy (MRS) demonstrated elevated choline, decreased N-acetyl aspartate and no evidence of lactate (not shown). MRI scans of his cervical and thoracic spine were normal. Magnetic resonance and computed tomography angiograms were normal.

![**Brain magnetic resonance images before (A-C) and after (D-F) treatment. (A)** T2-weighted FLAIR imaging demonstrates bilateral, diffuse hyperintense lesions in the white matter with sparing of the cortical U fibers. T1-weighted images following intravenous gadolinium administration in the **(B)** axial and **(C)** coronal planes show bilateral, symmetrical, linear contrast enhancement in a radial distribution throughout the white matter of the cortex and brainstem (arrows). **(D)** Following treatment with steroids and cyclophosphamide, T2-weighted FLAIR imaging demonstrates a dramat