An 84-year-old man in Northern Ireland complaining of frequent falls and weakness on the left side of his body discovered that it was due to a massive air pocket that had filled the bulk of a section of his brain.
Still, there were no red flags in the man's medical history.
Live Science wrote that an MRI scan on the man confirmed that the blank space in the man's brain was actually an air pocket in the portion of the brain known as the right frontal lobe. "He was a non-smoker and drank alcohol rarely".
Routine blood tests and regular health checks he undertook also failed to detect any sort of deformity, despite the huge hole inside his head.
"He was otherwise fit and well, independent with physical activities of daily living. and lived at home with his wife and two sons".
"(We) were all very perplexed by the images we saw!" Dr Finlay Brown, study co-author and physician at Causeway Hospital, told Newsweek.
The scans were so extreme, doctors wondered if the man had forgotten to disclose previous brain surgery or birth defects.
It turned out the man had pneumocephalus, or the presence of air in his cranium, a condition that is found in "nearly 100 per cent of cases after brain surgery", Brown said. In this man's case, the air cavity measured 3.5 inches at its longest point - an enormous size. "In my research for writing the case report I wasn't able to find very many documented cases of a similar nature to this one". "When the patient sniffed/sneezed/coughed he would most likely be pushing small amounts of air into his head".
Brown said the patient could have undergone surgeries: One that would decompress the air pocket in his head and another that would eliminate the tumour that had created the "one-way valve" and allowed air to move into the cavity in the first place.
As more air got in, it slowly pushed the brain aside, said Brown. He was later discharged and put on a secondary stroke prevention program, after which his left-sided weakness appeared to have been resolved. He was prescribed medication to prevent another stroke and instructions to monitor the feeling in his left side and after 12 weeks, he "remained well", according to the study.
"Because every now and then", Brown told LiveScience, "there will be a rare (or) unknown causation of these that could be overlooked".