Adult-onset Alexander disease (AOAD) is a rare leukoencephalopathy affecting predominantly the brainstem and cervical cord with insidious onset of clinical features. Acute onset is very rare and has yet been described only twice, to our knowledge. We report a 32-year-old hitherto healthy male who, after excessive consumption of alcohol, presented with stroke-like onset of symptoms including rigidospasticity, loss of consciousness, and bulbar dysfunction. MRI features comprised bilateral T2-hyperintensities of frontal white matter and basal ganglia as well as atrophy of medulla oblongata with a peculiar "tadpole" appearance, a pattern characteristic of AOAD. Mutation analysis of the GFAP gene revealed a heterozygous de novo 9-bp microduplication in exon 1. Adult Alexander disease may present with stroke-like features. MRI patterns of chronic neurodegenerative conditions may be recognizable even in acute neurological emergencies.