Acute haemorrhagic leukoencephalitis

**Definition:** Rare, severe, rapidly progressive inflammatory and haemorrhagic demyelinating disorder of the central nervous system, considered a variant of ADEM.

**Long definition:** Often preceded by a nonspecific respiratory infection about 10 days before the onset of neurological symptoms. Young males are most commonly affected, initially developing headache or dizziness and progressing over hours through stages of disorientation, confusion and drowsiness to coma. White matter lesions on MRI tending to be large and diffuse, with oedema and mass effect, as well as restricted diffusion in affected areas of the brain.