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in collaboration with
Dr Gérald Kierzek (Medical Director of Doctissimo)
Medical validation:
November 23, 2023
It is a treatment of hope for all patients with long Covid: an injection would correct the alterations in smell resulting from a coronavirus infection.
Do you know anosmia, parosmia and phantosmia? These are the famous changes in smell, which can occur in particular after a coronavirus infection. If these changes in smell are not the worst symptoms of forms of long Covid, they are no less disturbing and can last over time. Good news, however: scientists finally seem to have discovered a treatment for these smell problems… Explanations.
An anesthetic injected into the neck
The treatment used by the researchers is, in fact, not new.
Frequently used to treat headaches, Ménière’s syndrome or even complex regional pain syndrome (a neuropathic pain chronic which is characterized by a continuous sensation of burning or pain, editor’s note)the injection of an anesthetic into a group of nerves located on one side of the neck helps stimulate the autonomic nervous system (stellate ganglion).
However, if targeting this stellate ganglion block has already proven itself in these indications, it would also seem effective in restoring the sense of smell in patients with long Covid.
To verify this hypothesis, scientists injected the famous anesthetic into the stellate ganglion on one side of the neck of 54 patients diagnosed “with post-covid parosmia resistant to pharmaceutical and topical therapies“.
The injection also included a small dose of steroids, which may help relieve potential nerve inflammation caused by the coronavirus.
Result ? Among the candidates followed (37 in total), 22 patients reported an improvement in their sense of smell one week after the injection. Among them, 18 candidates showed significant improvement one month after the injection. At three months, an average improvement of 49% in symptoms was seen among the 22 patients.
26 patients also received a second injection on the other side of the neck six weeks later and again showed improvement in symptoms.
Overall, the trial was a success.
“The initial patient had an extremely positive outcome, almost immediately, with continued improvement, until symptoms resolved after four weeks.”, notes Dr. Adam C. Zoga, professor of musculoskeletal radiology at the Jefferson Health Institute. “We were surprised by some results, including a near 100% reduction in phantosmia in some patients throughout the trial.i.”
Furthermore, no complications or adverse events were reported.
An interesting avenue… which has some limitations
For Dr Gérald Kierzek, this therapeutic approach constitutes an interesting avenue for patients.
“Although we do not yet know the exact mechanism behind anosmia, we nevertheless know that it is a neurological problem, originating either from the receptors, or from the brain area, or from the area in between. This therapeutic approach, already widely used in anesthesia, is, in fact, interesting because it responds to the neurological hypothesis. The treatment affects the autonomic nervous system and it is this which would be the causee in persistent loss of smell”.
The study nevertheless has some limitations: the results are based on a very limited sample and have not yet been subjected to the usual evaluation process.
Some treated patients – who did not respond to the first contralateral injection – were also not sensitive to the second injection.
The authors of the study wish, in fact, to carry out a “further study“.