Early cerebral images of Alexander disease: report of one case.

Alexander disease is a neurodegenerative disorder characterized pathologically by demyelination and accumulation of eosinophilic hyaline bodies (Rosenthal fibers) within astrocytes. Demonstration of Rosenthal fibers on histological examination is considered a prerequisite for a definitive diagnosis. However, the CT and MRI scans may be highly suggestive of the disorder. We describe a patient who presented with subtle seizures at the age of 4 months. On examination, he was floppy with evident head lag. There was no visual following or social smiling. At that time, the brain MRI showed abnormal findings, with more white matter involvement and a characteristic periventricular rim. A diagnosis of Alexander disease was not made until he was one year old, when a repeated MRI showed the full-blown pictures typically seen in Alexander disease. The images fulfilled the diagnostic criteria proposed by van der Knaap in 2001. The early brain MRI findings in Alexander disease can be very characteristic and greatly different from those in the late stage.