The man that lost (part of) his mind.

An 84-year-old man presented to the emergency department following recurrent falls over several weeks and onset of new left-sided weakness. CT of the brain revealed a large air cavity (pneumatocoele) in the right frontal lobe thought to be secondary to an ethmoidal osteoma communicating through the cribriform plate allowing air to be forced into the skull under pressure. Subsequent MRI confirmed these findings and also revealed a small focal area of acute infarction in the adjacent corpus callosum. The patient had a prolonged hospital stay, declined neurosurgical intervention and was discharged home on secondary stroke prevention. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.