Loss of smell or anosmia is so common with COVID-19, it’s part of the diagnostic criteria. Parosmia, or diminished smell and taste, is even more common.
Up to 7% of the patients still experience smell and taste disturbances more than 12 months after the onset.
Why is there long term impact on smell after COVID resolves?
It was presumed the COVID affected smell by either directly impacting sense nerves or creating inflammation in areas of the brain associated with smell. Recently, researchers found olfactory neurons don’t have the critical surface receptor, angiotensin-converting enzyme 2 or ACE2, that lets COVID-19 into cells.
The answer probably lays with supportive cells in the nasal epithelium – sustentacular cells and basal cell – which support and nourish olfactory nerves. Unlike olfactory neurons, they are infected by COVID 19 because they express the ACE2 cell receptor and die during COVID infection.
Treatment options for anosmia
Traditionally, intranasal steroids and smell “retraining” therapies are offered. 2nd tier is intranasal vitamin A. Not many options after that have been rigorously examined. A study examining omega 3 fatty acid supplementation did not show benefit, while intranasal insulin showed positive results. This exploratory study showed improvement up to 4 weeks.
A promising new option - Stellate ganglion neve block for anosmia
There have been dramatic case reports and popular news articles showing the effect of stellate ganglion blocks on restoring sense of smell. While we await the results of a clinical trial yet to be published, a recent study sheds new light.
Canadian physicians surveyed different treatment options for anosmia after COVID infection– nasal steroids, olfactory retraining, and stellate ganglion blocks. All results were self-reported by patients. 209 patients responded and researchers stated,
“Despite the lower percentage of participants who underwent a stellate ganglion block (16%) this treatment presented the highest percentage of reported improvement (45%), followed by oral steroids (12%) and smell training (10%). “
They concluded that stellate ganglion blocks was the most successful treatment option.
Considering treatment with Stellate ganglion nerve blocks?
Before you consider a stellate ganglion block or SGB, you should see an ENT – Ear, nose and throat doctor to make sure there is no other reason for your loss of smell.
Stellate ganglion blocks are gaining traction as a promising therapy. While hopeful, more work should be done. However, anosmia and parosmia aren’t just inconveniences! The lack of smell and altered taste has serious effects on mood and health including weight loss, and depression. Because a stellate nerve block is a low-risk injection under ultrasound guidance, were proud to offer this treatment!
Interested in learning more? Dr. Steindler is an experienced, double board certified specialist in anesthesia and pain medicine. He teaches this and other advanced pain techiques to other physicians.
References
Olfactory dysfunction incidence and resolution amongst 608 patients with COVID-19 infection. Am J Otolaryngol. 2023 Sep-Oct;44(5):103962
Omega-3 Fatty Acid Supplementation for the Treatment of Persistent COVID-Related Olfactory Dysfunction. Am J Rhinol Allergy. 2023 Sep;37(5):531-540. doi: 10.1177/19458924231174799. Epub 2023 Jun 1.
Intranasal insulin for COVID-19-related smell loss. Eur Arch Otorhinolaryngol. 2023 Aug 22. doi: 10.1007/s00405-023-08176-6. Epub ahead of print.
Sowerby, L., Almubarak, Z., Biadsee, A., Rocha, T., & Hopkins, C. (2023). Coronavirus disease 2019 related parosmia: An exploratory survey of demographics and treatment strategies. The Journal of Laryngology & Otology, 1-5.
