A 1.5-year-old boy presented with progressive ataxia and meningeal irritation after a period of general malaise and fever. He was eventually admitted to a paediatric intensive care unit for respiratory insufficiency. A diagnosis of acute disseminated encephalomyelitis (ADEM) with pontine involvement was made. The patient was mechanically ventilated and treated with immunoglobulins and corticosteroids, after which he recovered almost completely. ADEM is characterised by rapidly progressive demyelination of the central nervous system. The exact incidence and aetiology are unknown. The disorder is considered to be an autoimmune reaction, and current treatment is aimed at the suppression of this reaction. Despite the dramatic clinical and radiological presentation of ADEM, the prognosis is favourable in most cases.