Medical scans revealed an 84-year-old man's brain had a 9cm air-filled pocket that was the reason he kept falling over, the Daily Mail reported.
His feelings of sudden weakness on his left side and the falls led doctors in Northern Ireland to believe he had suffered a stroke.
The air pocket was found to be in his right frontal lobe. It is the side that controls movement in the left side of the body.
Further inspection showed a bone tumour in his sinuses led to a minor stroke incident.
The unnamed patient declined surgery to remove the build-up of air. He instead opted to begin secondary stroke prevention.
Fascinated by his case, the doctors decided to publish a report of it in the BMJ Case Reports. It is titled 'The man that lost (part of) his mind'.