The 84-year-old man came to the emergency room with complaints that were not uncommon for a patient his age.
He had reported that he felt unstable in recent months, which culminated in repeated falls in recent weeks. In the three days before his hospital visit, his left arm and leg had weakened markedly.
Still, there were no warning signs in the medical history of man. He did not smoke. I rarely drank. A blood test did not detect anything abnormal.
"There was no confusion, facial weakness, visual or speech impairment," the doctors said in a summary of the man's case published on February 27 in the medical journal BMJ Case Reports. "For the rest, he was fit and well, independent of the physical activities of daily life … and lived at home with his wife and two children."
In other words, the doctors thought there was nothing evident to suggest a clear reason for their symptoms. In a way, they would not be wrong.
It was only after the CT scans and MRI scans that the patient's medical team made an alarming discovery: where most of the right frontal lobe of a man's brain should have been, there had simply been a large white space.
Finlay Brown, a physician who was working in the emergency department at the Causeway Hospital in Coleraine, Northern Ireland, at that time, recalls having reviewed the brain imaging scanners with the rest of the staff.  "(We were all) very puzzled by the images we saw." Brown told The Washington Post in an email.
The scans were so extreme that doctors wondered if the man had forgotten to reveal brain surgery or previous birth defects. . He said no.
It turned out that the man had pneumocephalus, or the presence of air in his skull, a condition that is found in "almost 100 percent of cases after brain surgery," Brown said. It can also occur after sinus infections and facial or cranial injuries, but with much smaller air or gas pockets.
In this case, the patient's pneumatocele or pressurized air cavity measures approximately 3½ inches at its longest point, according to the BMJ Case Reports article.
"In my research to write the case report, I could not find many documented cases of a similar nature to this one," Brown told The Post.
It is likely that the pneumatocele The formation of the tumor and its location had allowed something like an MRI, an osteoma or benign bone tumor, which had formed in the breast of man and was eroding through the base of the skull, said Brown.
"Unidirectional valve effect" that had gradually contributed to the cranial airway, he added.
"When talking to specialists, it seems to have been progressing insidiously for months or years," Brown said. "When the patient smelled / sneezed / coughed, he would most likely inject small amounts of air into his head."
It was also reported that the airway was a "rare cause" of a small effusion that had suffered, which had probably led to weakness of the left side and other symptoms that caused the man's visit to the hospital, according to the BMJ study Case Reports.
Brown said the patient could have had surgeries: one that would unpack the pocket of air in his head and another that would remove the tumor that had created the "one-way valve" and allow the air to move toward the cavity first.
However, the man rejected both, due to his age and other health factors. He was given medication to prevent a secondary stroke and sent home with orders to control if his left side weakness worsened.
His non-surgical approach is not without risk: the patient is likely to be at increased risk of infection, as it is still a passageway for air, and therefore bacteria and viruses, into his brain cavity, Brown said. .
"Unfortunately, as there are not many cases published, it is difficult to know the exact prognosis," Brown said.
So far, however, the man seems to be fine, despite the cranial air pocket. During a follow-up appointment 12 weeks after his hospital visit, the patient reportedly felt no weakness on his left side and "stayed well", according to his case study.
Brown told LiveScience that he wanted to publish this case study emphasizing "the importance of a thorough investigation even of the most common symptoms", since the frequent falls and imbalances of an octogenarian could have been easily canceled.
"Because from time to time, there will be a rare [or] unknown causality of these that could be overlooked," he said on the scientific news site.