A 45-year-old woman in Belgium came to an emergency department with a sudden headache at the back of her head that started right after she strained. A brain CT scan then turned up something few people would connect with such an ordinary effort: a small pocket of air inside her skull.
The case, published Sept. 15 in the American Journal of Case Reports, describes pneumocephalus, the medical term for air in the cranial cavity, after a Valsalva maneuver. That is the familiar move of bearing down against a closed airway, the kind of effort people make when lifting something heavy, straining on the toilet or trying to pop their ears.
What makes the report stand out is what doctors did not find. Neither CT nor MRI showed a defect that could explain how the air got in.
A Sudden Headache and an Unexpected CT Finding
The report comes from a team led by clinicians in the emergency department of CHU UCLouvain Namur-Godinne in Yvoir, Belgium. The patient had no recent trauma and no history of neurosurgery, the settings in which air inside the skull usually turns up.
Her pain came on abruptly in the occipital region, at the back of the head, and grew worse when she moved her head. Neurological and ear, nose and throat examinations were normal.
A brain CT showed a small, isolated collection of air in the posterior fossa, the lower rear compartment of the skull that houses the brainstem and cerebellum.
Headache is a frequent reason people seek emergency care, and the authors noted that its list of possible causes is long. Headache is also the most common symptom of pneumocephalus, they wrote, yet spontaneous cases without trauma or surgery are rare.
Two Scans Searched for a Way In and Found None
When air shows up in the skull, finding where it entered matters. According to a StatPearls clinical review hosted by the National Library of Medicine, pinpointing the location of the air and its entry point helps doctors separate benign cases from complex ones. The Belgian authors wrote that this search typically relies on MRI and input from ear, nose and throat specialists.
In this case, neither scan identified an anatomical defect.
That sets the case apart from other Valsalva-related reports. A 2019 case report described a healthy 29-year-old F-22 instructor pilot with recurrent pneumocephalus linked to the Valsalva maneuver. Doctors found defects in the pilot's sphenoid sinus and repaired them surgically, and the pilot returned to flying high-performance aircraft.
It also differs from a case MedicalDaily reported earlier this month, in which a different 45-year-old woman in Saudi Arabia, who often stifled her sneezes, developed air inside her skull. Her doctors traced it to a 2-millimeter gap in the bone between her nasal cavity and brain and repaired it endoscopically.
For the Belgian patient, the authors suggested that her favorable course points to spontaneous closure of a small pathway the straining may have created. That is an interpretation of how the case unfolded, not something the scans directly showed.
How Pressure Changes Can Pull Air into the Skull
The StatPearls review outlines two classic explanations. In the one-way ball-valve theory, air passes through a tear in the dura, the tough membrane covering the brain, and becomes trapped. The review links this mechanism to coughing, sneezing, and positive-pressure ventilation.
In the inverted soda bottle theory, a loss of cerebrospinal fluid lowers pressure inside the skull, creating a vacuum that draws air in until pressures even out. The review notes that this fluid loss can occur during Valsalva maneuvers.
The review also describes a third route. Blowing the nose, coughing, or sneezing can suddenly raise pressure in the sinuses, and air can then enter through defects in the skull base.
Pressure-related cases have surfaced in surprising places. A 2022 case report described spontaneous pneumocephalus on the fastest elevator in North America.
Still, cases like these are exceptions. StatPearls attributes almost 75% of pneumocephalus cases to head or facial trauma.
Rest, Time and a Message for Emergency Rooms
The woman did not need surgery. Doctors managed her conservatively; her symptoms gradually resolved, and follow-up imaging showed that the air had been reabsorbed.
That course fits what doctors call simple pneumocephalus. StatPearls says most patients have no symptoms and that the air disappears over time as surrounding tissue absorbs it. Conservative care can include bed rest, keeping the head of the bed raised, pain relief, oxygen therapy, and avoiding nose blowing, coughing, and sneezing.
The picture changes when trapped air builds pressure, a condition called tension pneumocephalus. The review describes it as life-threatening, with possible altered mental status, abnormal breathing and cardiorespiratory arrest, and says emergency surgical decompression is required when clinical signs appear.
The Belgian authors framed their report as a message to emergency physicians. They wrote that pneumocephalus remains underrecognized in emergency medicine and that the case shows why brain imaging matters when a headache is atypical. Their paper also reviews previously published cases of Valsalva-induced spontaneous pneumocephalus, adding one more example to a limited body of literature.
For the public, the case is not a reason to fear lifting groceries or clearing ear pressure. It is a single report of a rare event. Still, a sudden headache that feels unusual or different from past headaches deserves prompt medical attention.
Key Questions Answered
What is pneumocephalus?
It is the presence of air inside the skull. Head or facial trauma causes almost 75% of cases, according to a StatPearls review, and air is also common after brain surgery. Spontaneous cases are rare.
What happened to the woman in this case?
A 45-year-old woman in Belgium developed a sudden headache at the back of her head after a Valsalva maneuver. A CT scan showed a small pocket of air in the posterior fossa, the lower rear part of the skull.
Why did doctors consider the case unusual?
Neither CT nor MRI showed a defect that could explain how the air entered. The authors suggested that a small pathway created by straining may have closed on its own.
How can straining lead to air in the skull?
One proposed mechanism is that fluid loss during a Valsalva maneuver lowers pressure inside the skull, drawing air in. Another involves air passing through a tear and becoming trapped, as if by a one-way valve.
Did she need surgery?
No. She was treated conservatively, her symptoms resolved, and follow-up imaging showed the air had been reabsorbed.
Should people worry about straining or clearing their ears?
This single case does not show that everyday straining is dangerous. Anyone with a sudden, severe or unusual headache should seek prompt medical care.
