Researchers may have discovered an effective treatment for one of the most prevalent symptoms of long covid: a chronically altered sense of smell. Through a small study, the team observed significant improvement in many patients following an often-used minimally invasive procedure for treating pain and circulation issues. In some instances, people’s symptoms completely vanished.
Changes in smell and taste due to respiratory infections have been reported, although it took some time for this to be recognized as a common symptom of covid-19. As many as 30% to 80% of covid-19 patients can experience olfactory alterations. These changes consist of anosmia (partial or complete loss of smell), parosmia (distorted sense of smell, such as once-pleasant odors now smelling foul), and phantosmia (smelling nonexistent things).
Thankfully, smell-related changes brought on by covid-19 are usually temporary, resolving after a few weeks. However, a considerable number of people will continue to experience smell and taste issues for months, or even longer. For example, a November 2021 study suggested that up to 1.6 million Americans had developed chronic anosmia related to covid within the first two years of the pandemic. Other studies have indicated that chronic anosmia/parosmia is a common symptom of long covid.
While there are possible interventions that might prevent a permanent loss of smell if initiated early, such as smell training, there are no established treatments for covid-related chronic anosmia/parosmia. However, in a new study set to be presented at the annual meeting of the Radiological Society of North America (RSNA), researchers claim to have found a potential treatment.
The team chose to treat patients with stellate ganglion block – a procedure wherein local anesthetic is injected into a bundle of nerves located around the neck. These nerves are part of the autonomic nervous system, governing the body’s involuntary functions. The stellate ganglion is responsible for signaling many sympathetic nerve functions to the head, neck, and arms.
Stellate ganglion blocks are commonly used to alleviate symptoms caused by nerve-related conditions, such as shingles, phantom limb pain, or specific types of migraines. It was hypothesized that these nerves might also be involved in covid-related smell disturbances.
The study included 54 patients diagnosed with post-covid parosmia referred by ear, nose, and throat specialists. Patients initially received a stellate ganglion block on one side of the neck, guided by a prior CT scan to optimize the insertion position. The injection also included a small dose of steroids, which the researchers speculate might help reduce nerve inflammation caused by the virus.
The authors were able to follow up with 37 patients who underwent the procedure. Of these, 22 patients (59%) reported an improved sense of smell one week after the injection, while 18 patients reported continued progress a month later. The majority of those who improved after the first injection also saw continued improvement after a second injection six weeks later.
During the three-month trial period, the average improvement in symptoms among responders was 49%, with some experiencing complete recovery.
Lead author Adam Zoga, professor of musculoskeletal radiology at Jefferson Health, remarked, “The initial patient had a tremendously positive outcome, almost immediately, with continued improvement to the point of symptom resolution at four weeks. We have been surprised at some outcomes, including near 100% resolution of phantosmia in some patients, throughout the trial.”
It’s important to note that the findings are based on a very small sample size and have yet to go through the typical peer-reviewed process. Nevertheless, given the scarcity of available options, this potential treatment appears to be meritorious of further exploration, the study authors suggest. “Other treatments have failed to date,” Zoga stated. “This injection is working.”
