An 11 year old boy walked into our accident and emergency department with his mother having woken up with headache four hours ago. He was known to have mild learning difficulties for speech and language, but was otherwise previously fit and healthy. He was not on any medications, and he did not have any history of trauma. He had vomited twice at home. On initial examination, he did not have a high temperature, rash, or meningeal symptoms, and his Glasgow Coma Scale score was E4 M6 V5. He had no neurological signs or papilloedema and the pupils were normal. He had no neck stiffness or meningeal signs. His pulse …