A technique for restore lost sense of smell in Long Covid patients. The “minimally invasive” procedure – lasting 10 minutes, without the need for sedation or intravenous analgesia – involves injecting an anesthetic directly into the stellate ganglion on one side of the neck, and stimulating the regional autonomic nervous system. It was developed by a team of American scientists – whose study appears among the main works of the annual meeting of the Radiological Society of North America (RSNA), scheduled in Chicago from November 26th – who dealt with a condition common to several people who, despite having left the virus behind, are unable to get rid of some symptoms for many months. One is right the so-called parosmia, an alteration of the sense of smell that does not allow odors to be perceived correctly.
“Patients may develop disgust for foods and drinks they previously enjoyed,” explains Adam C. Zoga, professor of musculoskeletal radiology at Jefferson Health in Philadelphia, Pennsylvania (USA). And some get to experience a condition they feel for ‘phantom’ smells, disgusting or pleasant, which are not really in the environment. The loss of smell was one of the symptoms that affected the most at the beginning of the Sars-CoV-2 pandemic. Recent research has found that up to 60% of Covid patients have been affected. But while most recover over time, for some parosmia has not remained just a bad memory. Indeed, these people had to live with the problem for months or even years after infection, with a negative impact on appetite and general quality of life. The authors of the research therefore worked on a way to restore the sense of smell in these patients with Long Covid. And they thought about a minimally invasive, imaging-guided procedure that might be able to achieve the goal.
In detail, the idea was to evaluate the potential benefits of blocking the stellate ganglion. These are nerves on each side of the neck, part of the autonomic nervous system, which regulate involuntary processes including heart rate, blood pressure, breathing and digestion. They transmit certain signals to the head, neck, arms and a portion of the upper chest. The stellate ganglion block procedure has been used with varying degrees of success to treat a number of conditions, including cluster headache, phantom limb pain, Raynaud’s and Meniere’s syndromes, angina, and cardiac arrhythmia.
“We weren’t entirely sure it would work for parosmia,” Zoga pressed. For the study, 54 patients were referred to an ear, nose and throat specialist after at least 6 months of post-Covid parosmia resistant to drug and topical therapies. And the procedure was performed. The researchers added a small dose of corticosteroid to the anesthetic suspecting that the Covid virus could cause inflammation of the nerves.
“The initial patient had an extremely positive outcome, almost immediately, with continued improvement until resolution of symptoms after 4 weeks,” says Zoga. “We were surprised by some results, including a nearly 100% resolution” of the phantom odor problem “in some patients during the study.” Follow-up was obtained for 37 patients (65%). It found that 22 (59%) of these reported an improvement in symptoms one week after the injection. And 18 (82%) reported significant progressive improvement within one month of the procedure. At three months, there was an average symptom improvement of 49% (range 10% to 100%) among the 22 patients.
For 26 people there was a second injection given to the other side of the neck after an interval of at least 6 weeks. This was not effective in patients who had not responded even to the first injection, while for 86% of those who reported some improvement after the first injection there was further progress. No complications or adverse events were reported. “Other treatments to date have failed,” concludes Zoga. “This injection is working.”
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