Case 1

A boy presented to a district general hospital on the eve of his first birthday. He had collapsed at home, and his parents reported that for three days he had had fever, anorexia, vomiting, and increasing drowsiness. On arrival at hospital he was poorly perfused, could barely be roused, and his anterior fontanelle was bulging. The boy's blood pressure was 117/66 mm Hg and his occipitofrontal circumference was 50.6 cm (>90th centile). Initial investigations showed haemoglobin concentration 81 g/l, white cell count 23.9×109/l (neutrophils 18.9×109/l), platelets 226×109/l, serum urea and electrolytes normal, and C reactive protein 137 mg/l. He improved after resuscitation with plasma; then, because of recurrent episodes of bradycardia, he was intubated and ventilated. Intravenous ceftazidime and penicillin were given. The boy had been previously well, was fully immunised, and had been making appropriate neurodevelopmental progress. His large head had been noted previously but was attributed to a familial tendency and was not investigated.

The patient was transferred to the regional paediatric intensive care unit, where computed tomograms showed dilatation of the lateral and third ventricles with some reduction of the extra axial spaces (fig 1). There was no crowding of the foramen magnum, effacement of the basal cisterns, periventricular oedema, or loss of grey-white differentiation. Taking into account the history of a large head, it was concluded that …