A patient (47-year-old female) presented with right-sided headache followed by persistent severe headache, left-sided numbness followed by left-sided weakness, and drowsiness (with severe left upper limb weakness, mild left leg weakness and hemisensory loss), 7 days the onset of COVID-19 symptoms. The CT head imaging demonstrated marked right hemisphere vasogenic oedema with midline shift. The head MRI demonstrated severe right hemispheric vasogenic oedema with a leading edge on contrast imaging, and smaller areas of T2 hyperintense changes in the left hemisphere, therefore a diagnosis of an acute haemorrhagic leukoencephalopathy form of ADEM was made. After 48 hours of being treated with high dose intravenous methylprednisolone (1 g daily for 5 days), her level of consciousness dropped and her right pupil became fixed and dilated. Because of her decline, she underwent emergency right hemi-craniectomy. During the operation, a brain biopsy was taken that suggested hyperacute ADEM. After the procedure, she was treated with oral prednisolone (60 mg daily), IVIG (for 5 days), and was extubated (4 days). Her clinical condition and physical strength continue to improve, with brain tissue that is negative in PCR for SARS-CoV-2.