A team of researchers may have found an effective treatment for one of the most common symptoms of long covid: a chronically altered sense of smell. In a small study, the team found that many patients improved after undergoing a minimally invasive procedure often used to treat pain and circulation problems. In some cases, the symptoms have completely disappeared.
People often experience changes in smell and taste following a respiratory infection, even if it takes Sometimes for this to be widely recognized as a common symptom of covid-19. Between 30 and 80% of people with Covid-19 may develop changes in their sense of smell. These include anosmia (a partial or complete loss of smell), parosmia (a distorted sense of smell, such as once pleasant things smelling bad), and phantosmia (smelling things that are unpleasant). ‘do not exist).
Fortunately, odor-related changes caused by covid-19 are usually self-limiting and disappear after a few weeks. But a notable percentage of people will continue to experience problems with smell and taste for months or longer. A study from November 2021 estimated that up to 1.6 million Americans had developed chronic covid-related anosmia during the first two years of the pandemic, for example. Other studies have suggested that chronic anosmia/parosmia is one of the most common symptoms of long covid.
Although there are possible interventions that could prevent permanent loss of smell if used early enough, such as smell training, there is no established treatment for chronic covid-related anosmia/parosmia. But in a new study to be presented later this month at the annual meeting of the Radiological Society of North America (RSNA), researchers say they may have found one.
The team decided to treat patients with a star ganglion block, a procedure in which a local anesthetic is injected into a bundle of nerves around the neck (the stellate ganglion). These nerves are part of the sympathetic nervous system, which in turn is part of the autonomic nervous system. The autonomic nervous system governs our body’s involuntary functions, while sympathetic nerves regulate our “fight or flight” response to stressful situations. The stellate ganglion is responsible for sending many sympathetic nerve signals to the head, neck, and arms.
Star ganglion blocks are commonly used to treat symptoms caused by nerve conditions, such as shingles, phantom limb pain, or certain types of migraines. The team hypothesized that these nerves could also play a role in covid-related smell disorders.
The study included 54 patients diagnosed with post-covid parosmia who were referred to the authors by ear, nose and throat specialists. Patients initially received 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 researchers believe could help relieve any nerve inflammation caused by the coronavirus.
The authors were able to follow 37 patients who benefited from the procedure. Of these, 22 patients (59%) reported an improvement in their sense of smell one week after the injection, while 18 patients reported continued improvement one month later. Twenty-six patients also returned for a second injection on the other side of the neck six weeks later, and most of those who improved after the first dose saw continued improvement after the second.
Overall, the average improvement in symptoms among responders over the three-month trial period was 49%, although some people appeared to experience complete recovery.
“The initial patient had an overwhelmingly positive outcome, almost immediately, with continued improvement until symptom resolution at four weeks,” said lead author Adam Zoga, professor of musculoskeletal radiology at Jefferson Health in Philadelphia, Pennsylvania, in a study. statement of the RSNA. “We were surprised by some results, including near 100% resolution of phantosmia in some patients, throughout the trial. »
The results are based on a very small sample and have not yet been subjected to the usual peer review process. They must therefore be considered with greater caution for the moment. And even in the best possible light, it’s likely that stellate ganglion blocks won’t be able to help everyone who has lost their normal sense of smell due to covid-19. But given the lack of options available, this potential treatment certainly seems worthy of further study, the study authors say.
“Other treatments have failed so far,” Zoga said. “This injection works.”