- We present the case of a young man with recent cytomegalovirus (CMV) infection who was admitted with generalised seizure and coma. Computed tomography scan and magnetic resonance imaging (MRI) on admission were normal. Despite transient initial improvement he rapidly deteriorated leading to repeated MRI that revealed findings highly suggestive of acute haemorrhagic leucoencephalitis (AHLE). The patient died despite treatment with pulse methylprednisolone and intravenous immunoglobulin. Acute disseminated encephalomyelitis (ADEM)/AHLE should be considered in the differential diagnosis of rapid neurological deterioration even when initial imaging is normal. This case report underscores the importance of early diagnosis as early aggressive treatment may improve outcome.