Criteria for an MRI-based diagnosis of Alexander disease – 4 or more of the following:
(1) extensive cerebral white matter abnormalities, which may be maximal in the frontal lobes
(2) periventricular rim of (a) decreased signal intensity on T2-weighted images and (b) increased signal intensity on T1-weighted images
(3) abnormalities in the thalami and basal ganglia (atrophy, swelling, altered signal intensity on T2-weighted images)
(4) brain stem abnormalities
(5) contrast enhancement of one or more of the following: ventricular lining, periventricular rim, frontal white matter, optic chiasm, fornix, basal ganglia, thalami, dentate nucleus, brain stem
Additional MRI changes may include:
(1) involvement of the posterior fossa structures
(2) multifocal tumor-like brain stems lesions
(3) garland-like feature along the ventricular wall
(4) characteristic pattern of contrast enhancement
(5) atrophy or signal abnormalities of the medulla or spinal cord
