Long COVID patients who lost sense of smell can be helped with surgery

A surgical operation normally carried out to correct a blocked nasal passage may help patients who lost their sense of smell after contracting a COVID-19 infection, according to new research by UCL and UCLH researchers published in the journal Facial Plastic Surgery.

The research clinicians had already shown in a 2023 paper that the procedure—functional septorhinoplasty (fSRP)—can restore the sense of smell following a viral infection or trauma.

They have now found it could be an option for long COVID patients with an impaired sense of smell (persistent olfactory dysfunction of more than two years) if existing treatments such as smell training and oral/topical corticosteroids fail. The researchers, however, also cautioned that this was early stage research and replicating the results in larger groups of people will be needed first.

The fSRP procedure aims to improve nasal blockage by correcting a bent or narrow nose which, as a result, also increases the nasal airflow into the olfactory region. It is thought this improves the sense of smell by optimizing delivery of odorants to the roof of the nose (called the olfactory cleft), where the sense of smell is located. The working theory is that “increased odorant delivery” to the olfactory cleft “kick starts” recovery.

The research was carried out between October 2022 and May 2023 at the Royal National ENT and Eastman Dental Hospitals at UCLH. It was led by Professor Peter Andrews (UCL Ear Institute and senior consultant surgeon in rhinology and facial plastic surgery at UCLH) and Dr. Alfonso Luca Pendolino (UCL Ear Institute and UCLH).

Professor Andrews said, “We found promising results suggesting that nasal surgery which increases the olfactory nasal airflow could reactivate sense of smell recovery for people with persistent long COVID. Further research will be needed to confirm our findings in a larger group of patients, and determine whether this treatment should be used more widely.”

The team compared two groups of long COVID patients with a comparable degree of an impaired sense of smell and similar baseline characteristics. Twelve patients had fSRP, while a control group of 13 patients continued with smell training for the entire length of the study.

Sense of smell was measured over the duration of the study by using the Sniffin’ Sticks test, a test widely used in clinical practice which assesses smell by using pen-like odor-dispensing devices.

Results of the study showed a significant benefit in terms of increased nasal airflow and improved sense of smell in the group of patients who had fSRP. Sense of smell improved in all the patients who had the procedure. In the group of patients who did not receive fSRP, sense of smell did not improve, and further decreased in 40% of them.

The procedure was particularly good at increasing odor sensitivity by lowering the odor threshold—the minimal concentration of an odor a person can actually smell—which is specifically noted in long COVID patients with an impaired sense of smell.

Penelope Newman, 27, from South London, who was a participant in the trial, said, “Before I had the surgery on my nose, I had begun to accept that I would probably never be able to smell or taste things the way I used to. It seemed dire, and after around two and a half years of parosmia, I had totally changed my lifestyle.

“For those who have experienced this, they will know how isolating it can be. The food I could cook and eat was so limited, and I couldn’t go out to restaurants as I would feel unwell. Getting something as drastic as surgery was a risk I was willing to take on the small chance it might help.

“Since the surgery, I have begun to enjoy food and smells the same way I used to. I can now cook and eat garlic and onions (and people can cook for me too). I can go out to eat with my friends and family.

“My taste and smell have almost returned to normal—I’m not sure if it will ever fully return as I still have a small reduction in it, but I am so glad that I am no longer as isolated as I once was. I will never take my senses for granted ever again.”

As part of their study, the researchers are now looking at the brain changes that happen following fSRP which could explain the long-term olfactory benefits achieved following the surgery.