Doctors stress that it's a very rare occurrence, but one woman's pre-surgery COVID-19 nasal swab test appears to have triggered a release of cerebrospinal fluid into her upper nasal cavities.
The incident was tied to a tiny gap in the bones of the woman's skull -- an encephalocele.
"The [COVID-19 test] swab itself did not result in a violation of the bony skull base, but rather the invasive test caused trauma to the patient's preexisting encephalocele," reported a team led by Dr. Jarrett Walsh. He's with the department of otolaryngology-head and neck surgery at the University of Iowa Hospitals and Clinics, in Iowa City.
As the researchers explained, millions of people worldwide are enduring the discomfort of nasal swab tests for SARS-CoV-2 during the pandemic. These tests are thought to produce more accurate results than samples taken further down the nasal tract, but their reach high up in the nasal passages makes them less than enjoyable.
In the case under discussion, a 40-year-old woman underwent a standard nasal swab test for COVID-19 prior to undergoing an elective hernia surgery.
Soon after the test, she experienced mucus discharge from one side of her nose, headache and vomiting. Investigation at the hospital revealed a leakage of cerebrospinal fluid -- a vital fluid that's normally sealed off from entering the nasal cavities.
"This represents a truly rare complication of this common and critical diagnostic test," said Dr. Dennis Kraus, an ear, nose and throat specialist who wasn't involved in the new report. He's vice chair of otolaryngology-head and neck surgery at Lenox Hill Hospital in New York City.
Imaging tests revealed the previously undiagnosed gap in the woman's skull (the encephalocele). It was this vulnerability, coupled with the "trauma" of the nasal swab, that spurred the fluid leak, the doctors believe. In this patient's case, timely surgery to repair the gap in the skull stopped the leak.
These cases are exceedingly rare, the experts noted. While a typical person wouldn't face any danger of a cerebrospinal fluid leak from a swab test, "prior surgical intervention [in the nasal/sinus area], or pathology that distorts normal nasal anatomy, may increase the risk of adverse events associated with nasal testing," Walsh's group reported.
For that reason, alternative types of COVID-19 tests should be considered for patients who are known to have "skull base defects," the team said, or any history of surgeries in areas adjacent to the swab test site.
According to Kraus, the incident "underscores the necessity of adequate training of those performing the test and the need for vigilance after the test has been performed."
The report was published online Oct. 1 in JAMA Otolaryngology-Head and Neck Surgery.
There's more on COVID-19 testing at the U.S. Centers for Disease Control and Prevention.