Jane, a 13-year-old girl, had a 4-week history of abnormal left limb movements and falls. The first problem noted was a high stepping gait on the left which resolved over a few days. Several falls, presumed to be vasovagal faints, ensued and a few days prior to her admission she collapsed after her left leg ‘gave way’. Following this collapse she had persisting left arm weakness and speech difficulties. The general practitioner was concerned she had suffered a stroke and he referred her to hospital for further assessment.

The history obtained by the registrar established Jane had been born prematurely at 27 weeks gestation but the pre-, peri- and postnatal course had otherwise been uneventful. She was described as having mild learning difficulties but was in mainstream education with support. In the previous year, she had been seen by the Child and Adolescent Mental Health Service (CAMHS) because of mood swings and some self-harming behaviours. These were attributed to bullying at school and a bereavement reaction to the death of her mother 5 years earlier. With her current presentation, Jane had developed a right hand preference having previously been left hand dominant. She could no longer walk upstairs and had to crawl up while holding on to the banister with her right hand. During the day, her family thought she appeared confused and she would talk for prolonged periods of time, as if to another person, when no-one else was present. She had not slept well for several days and had started to wander about the house, looking for objects which she thought had been lost. There was also a history of fatigue and moderate …