Authors: Thomas Mac Mahon / Editor: Turlough Bolger / Reviewer: Thomas Mac Mahon / Codes: IC6, IP1, IP3, NeuP2, NeuP6, SLO5 / Published: 23/02/2024

A 10-year-old girl is referred to your Emergency Department (ED) by her GP with a two-week history of lethargy and temperatures. She had initially been diagnosed with tonsillitis and started on phenoxymethylpenicillin. Over the last week, she has become progressively weaker with poor oral intake and temperatures up to 38.5°C. Her parents have become more concerned over the last 48 hours as she has developed an unsteady gait, headaches, been slow to respond to simple questions, and vomited three times. 2 hours prior to her arrival she collapsed at home, was doubly incontinent and unable to stand.

She has a background of neurofibromatosis, type 1. She is on no regular medications and has no allergies. Her vaccines are up to date. No family members are unwell.

On your assessment she looks pale and unwell. She has a temperature of 37.9°C and is rigoring. Her pulse rate is 125/minute, blood pressure 128/81, respiratory rate 26/minute and oxygen saturation of 100% on room air. Her random capillary blood glucose is 6.9 mmol/l. She has erythematous tonsils and a white-coated tongue; the remainder of her ENT examination is unremarkable. Her neck movements are unrestricted. She has no rash. Cardiovascular, respiratory and abdominal examinations are unremarkable. Her pupils are equal and reactive; fundoscopy is normal. She is orientated and follows commands, but gives single word answers to questions, with a considerable delay in replying. She has 4/5 power in her left upper limb, globally reduced reflexes, an upgoing left plantar and an ataxic gait, falling to the left. There is no dysdiadochokinesis or past pointing.

Urgent blood tests show a raised white cell count (22.4), with a marked neutrophilia (17.5) and a raised CRP (107.3). Her infectious mononucleosis screen is negative. Her electrolytes and renal function are normal. Chest x-ray is normal. Urinalysis shows 3+ ketones.

You perform an urgent MRI-Brain with gadolinium contrast, selected images of which are below.