We report a 37-year-old woman with acute disseminated encephalomyelitis (ADEM) who presented with progressive vertigo. A central nervous system disorder was initially suspected because gaze-evoked torsional nystagmus was observed and electrical nystagmography (ENG) revealed abnormal eye movements with saccadic ocular pursuit and pathological optokinetic nystagmus. Finally ADEM was diagnosed by the clinical symptoms and the characteristic patterns of brain MRI. It is rare for otolaryngologists to examine patients with ADEM. ADEM takes an acute course and can present a grave state and therefore needs early diagnosis, early treatment. We have to keep ADEM in mind in the diagnosis of vertigo.