Hypertrophied fibrillary astrocytes were found throughout the white matter. The infantile form is the most severe of the three. Afflicted children may present at birth, but symptoms usually develop over the first six months of life. The juvenile and adult forms are less affected. Bulbar symptomatology dominates the juvenile form, e.g., dysarthria, vocal cord paralysis, difficulty swallowing, and decreased facial sensation.
Onset occurs after infancy, and there is preservation of intellectual level and sensory functioning.
In the adult form, the findings are similar to multiple sclerosis. For all classifications of Alexander's disease, brain biopsy and neuroimaging are the only studies currently available to support a clinical diagnosis. Histology of brain biopsies shows characteristic gliosis, dysmyelination, and subpial Rosenthal fibers. EEG patterns in Alexander's disease appear distinct. Pridmore et al.