Study Finds A New Treatment To Restore Loss Of Smell From In Long COVID Patients

We're all aware of how the SARS-CoV-2 virus that causes COVID-19 infection affects our respiratory health. Common symptoms include fever, cough, fatigue, muscle and body aches, and, in some cases, loss of smell and taste.

Additionally, COVID-19 can lead to a range of long-term effects, often referred to as 'long COVID' or post-acute sequelae of SARS-CoV-2 infection (PASC), which can affect people across all age groups. One of the common ailments associated with the condition is loss of smell, or parosmia, a distorted sense of smell, for which researchers have been looking for a treatment. 

Fortunately, a new study has found a novel treatment that could help people struggling with smell loss and alternations regain their olfactory abilities. But before we get into the details, let us understand how COVID causes loss of smell.

Also Read: Factors That Can Cause Loss Of Smell Other Than COVID-19 

Loss Of Smell - A Common COVID-19 Symptom

Loss of smell, also known as anosmia, and parosmia, characterised by a distorted sense of smell, are common and distinctive symptoms of COVID-19. Many individuals infected with the SARS-CoV-2 virus experience a sudden loss of their sense of smell or taste. This symptom often occurs early in the course of the infection and can sometimes be the only symptom in otherwise asymptomatic individuals. 

A 2022 study published in Rhinology Online found that at one-year after their COVID-19 diagnosis, 15.2% of participants experienced persistent olfactory dysfunction, whereas 66.7% of participants reported having parosmia at one point during their course of infection.

While the exact way by which COVID-19 affects the sense of smell is not completely understood, it is believed to be related to the virus's impact on the olfactory system. 

The SARS-CoV-2 virus primarily enters human cells by binding to angiotensin-converting enzyme 2 (ACE2) receptors, which are found in various tissues, including the respiratory and olfactory systems.

In the case of the sense of smell, the virus may directly damage the olfactory sensory neurons or the supporting cells in the olfactory tissues, which can disrupt the normal functioning of the olfactory system, leading to anosmia, hyposmia (partial loss of smell), or parosmia. Moreover, the immune response triggered by the infection could contribute to inflammation and further impact the olfactory system.

New Treatment To Restore Smell

A new study presented at the annual meeting of the Radiological Society of North America (RSNA) involved a group of 54 people, who had shown resistance to pharmaceutical and conventional medical interventions for parosmia. They were then administered a stellate ganglion block, wherein anaesthetic is injected directly into the stellate ganglion on one side of the neck to activate the local autonomic nervous system. This minimally invasive procedure lasts for less than 10 minutes and does not require sedation.

Among the participants, researchers conducted a follow-up with 37 participants, 22 of whom noted enhanced symptoms a week following treatment. Furthermore, a majority of these participants experienced substantial additional improvement one month post-treatment.

Also Read: Study Reveals Why COVID-19 Can Infect Sensory Neurons, Explaining Loss Of Smell and Taste

After three months, researchers observed an average 49% enhancement in symptoms within the group. Additionally, 86% of those who responded positively to the initial injection reported further improvements after a second injection administered to the opposite side of the neck six weeks later.

In a press release, Dr Adam Zoga, a study author and a professor of musculoskeletal radiology at Jefferson Health in Philadelphia, Pennsylvania, said, "The initial patient had a tremendously positive outcome, almost immediately, with continued improvement to the point of symptom resolution at four weeks."

He added, "We have been surprised at some outcomes, including near 100% resolution of phantosmia in some patients, throughout the trial."

Smell Training And Other Ways To Recover From Parosmia

Talking to the team of OnlyMyHealth, Dr Ashutosh Shukla, Senior Director - Internal Medicine & Medical Advisor, Max Hospital, Gurgaon, shared smell training is mostly done by picking 3-4 different scents and breathing them in deeply for around 5-10 minutes twice a day. 

According to the doctor, strong smells such as cloves, citrus, coffee, and lavender are generally recommended.

Moreover, it is important to avoid smell triggers, which involve foods like chicken, meat, onions, eggs, garlic and rice.