Doctors in Northern Ireland have discovered a man with a huge air pocket in his head where part of his brain is supposed to be.
The 84-year-old went to hospital as he was often falling over due to being unsteady on his feet, according to the NZ Herald.
He also said that his left leg and arm felt weak, however after a few tests doctors couldn't seem to find a valid reason for this.
The British Medical Journal (BMJ) reported that aside from the weakness and unsteadiness he was "otherwise fit and well."
Staff decided to give the man a CT and MRI scan, and it was then that they saw the blank where some of his brain should have been, measuring 3.5 inches long.
Physician at Causeway Hospital, Finlay Brown, told the Washington Post that doctors were "perplexed" by the scans as the man had not had any surgery on his brain or defects at birth.
It later turned out that the pneumocephalus, which means there is air in the cranium, has probably been caused by a benign bone tumour which means the base of the skull has eroded allowing air in, likely to have been going on for months and years.
Brown said air could have entered when the man sniffed, sneezed or coughed, each time making the air pocket larger.
The man was offered operations in order to help remove the air pocket, however due to his health he is only taking medication for the issue instead.
Brown added that "unfortunately, as there are not many cases [of pneumocephalus] published, it is hard to know the exact prognosis."