A team of researchers may have found a promising treatment for one of the more common symptoms of long covid: a chronically changed sense of smell. According to a study set to be presented later this month at the annual meeting of the Radiological Society of North America (RSNA), the team found that many patients improved after undergoing a minimally invasive procedure often used to treat pain and circulation problems. In some cases, people’s symptoms disappeared altogether.
Researchers believe that smell-related changes caused by covid-19 are typically self-limiting and go away after a few weeks. However, a noticeable percentage of people continue to experience smell and taste problems for months or even longer. A November 2021 study estimated that up to 1.6 million Americans had developed covid-related chronic anosmia within the first two years of the pandemic. Other studies have suggested that chronic anosmia/parosmia is one of the most common symptoms of long covid.
While there are possible interventions that might be able to prevent a permanent loss of smell if used early enough, such as smell training, there are no established treatments for covid-related chronic anosmia/parosmia. However, the team’s study has shown promising results by treating patients with a stellate ganglion block, a procedure in which local anesthetic is injected into a bundle of nerves located around the neck.
The study involved 54 patients diagnosed with post-covid parosmia who had been referred to the authors by ear, nose, and throat specialists. The patients were initially given a stellate ganglion block on one side of the neck, with a prior CT scan used to find the best position for insertion. The injection also included a small dose of steroids, which the researchers speculate might help relieve any nerve inflammation caused by the coronavirus.
The results showed that the majority of patients reported an improved sense of smell one week after the injection, with continued progress a month later. Overall, the average improvement in symptoms among the responders during the three-month period of the trial was 49%, though some people experienced a complete recovery.
“The initial patient had a tremendously positive outcome, almost immediately, with continued improvement to the point of symptom resolution at four weeks,” said lead author Adam Zoga, professor of musculoskeletal radiology at Jefferson Health in Philadelphia, Pennsylvania. “We have been surprised at some outcomes, including near 100% resolution of phantosmia in some patients, throughout the trial.”
The findings are based on a very small sample size and have yet to go through the typical peer-reviewed process. So they should be viewed with added caution for now. Nonetheless, the study authors believe that this potential treatment is worth further investigation.
“Other treatments have failed to date. This injection is working,” Zoga said.