Relief may be on the way for people whose sense of smell and taste became distorted after suffering a COVID-19 infection.
A new study led by researchers at Western University suggests there may be a potential new treatment.
Since COVID-19 began spreading at the end of 2019, numerous people infected with the virus have reported suffering a smell dysfunction called parosmia long after recovery. Parosmia changes comforting smells into repulsive ones. Until now little research has been done on its symptoms, progression, effects on quality of life, and treatment options.
The study, published in the Journal of Laryngology and Otology, showed most people reported a loss of smell about three days after their initial COVID-19 symptoms. Recovery was reported about four weeks after infection and the onset of parosmia came approximately 12 weeks post-infection.
Only three per cent of respondents reported a full recovery, 22 percent had a slight improvement, and 42 percent had no improvement.
"The psychological impact of parosmia is substantial, with depression being the most reported condition," said Dr. Leigh Sowerby, associate professor in the department of otolaryngology-head and neck surgery at Western’s Schulich School of Medicine & Dentistry.
Other impacts post-COVID parosmia had on patients' lives include loss of appetite, significant weight loss, anxiety, nausea, mood swings, and even suicidal thoughts.
Some of the top triggers for the disorder include onions, garlic, meat, coffee, peanut butter, chocolate, fried foods, and perfume.
The study established stellate ganglion block (SGB) as a possible, effective treatment to help those with a distorted sense of smell.
The procedure involves injecting a local anesthetic into the stellate ganglion, a collection of nerves in the neck. Currently, SGB is primarily used to diagnose and treat chronic neuropathic pain conditions such as phantom limb pain. It has also been used to treat circulation problems and nerve injuries.
"The stellate ganglion controls sympathetic signals to the head, neck, arms and part of the chest. Temporarily blocking these signals through an anesthetic injection could alleviate the distorted sense of smell in patients as it appears that part of the problem is in how the brain is perceiving the signal,” Sowerby said.
He calls the procedure low-risk adding that it seems to be the most effective treatment to-date.
The study focused on 209 adult patients. They were surveyed regarding the effectiveness of their treatment options.
According to the survey the most common treatments trialed by respondents include:
-Smell training - used by 74 per cent of patients
-Nasal Corticosteroid Sprays - used by 49 per cent of patients
-Vitamin A Drops - taken by 20 per cent of patients
-SGB - used by 16 per cent of patients
While it's the least popular treatment, the survey showed that SGB had the highest rate of effectiveness. Forty-five per cent of patients reported significant improvement in their condition.
Sowerby and his team are now looking to conduct a clinical trial to get further insight into the potential treatment.
“This survey is the first step to get more data on patients and their experiences," said Sowerby. "Further research is needed to understand the efficacy and the benefit of SGB for post-COVID parosmia.”
