The case

A 49-year-old woman presented in July 2014 with a 1-week history of confusion, particularly with memory and word-finding difficulties. She also gave a 3-month history of reduced hearing, initially acutely in the right ear, and a 2-day history of vertigo and vomiting. The vertigo resolved but over the next month she noticed hearing loss affecting the left side as well. Her husband reported that she had had an episode of disorientation and confusion 2 months earlier; this had only lasted a day but her cognition had been completely normal since. She had no vascular risk factors, past medical history or history of using any recreational drug.

On examination, she was afebrile and normotensive but was disorientated to day and date. Visual acuity and fundoscopy were normal. Eye movements were normal, as were the other cranial nerves, apart from bilateral hearing loss. The head impulse test was negative. There was mild impairment of rapid alternating movements in the right arm and difficulty with tandem gait.

The Montreal cognitive assessment test gave a score of 18/30. A delirium screen with blood tests, including a full blood count, electrolytes, liver function tests, C reactive protein and erythrocyte sedimentation rate, was normal. A chest radiograph, urine and blood cultures were negative. A CT scan of head was normal but an MRI scan of brain was floridly abnormal (figure 1).

The MRI scan of brain shows multiple areas of high T2 and fluid-attenuated inversion recovery (FLAIR) signal within the cerebrum, corpus callosum, cerebellum and brainstem.

Acute disseminated encephalomyelitis (ADEM) was our primary differential diagnosis. There …