Emerging research proposes that a stellate ganglion block injection may aid long COVID sufferers in regaining their sense of smell. Administered into neck nerves, the injection shows promise in alleviating parosmia, a condition affecting smell perception.
Despite positive indications, some researchers express concerns about study design limitations. Dr. Leigh Sowerby, an otolaryngology professor, criticizes the research, noting the substantial loss of follow-up patients, indicating severely limited data.
Stellate Ganglion Block Shows Promise in Alleviating Post-COVID Parosmia
During the early days of the pandemic, smell and taste changes were identified as common COVID-19 symptoms, with a U.K. study revealing that 43% of those reporting loss of smell in March 2020 experienced parosmia six months later. However, the origins and treatment of post-viral parosmia have remained elusive.
Recent research, titled "Stellate Ganglion Block with CT Guidance for Post-COVID Parosmia" from Jefferson Health in Philadelphia, suggests that the stellate ganglion block procedure can somewhat alleviate parosmia in individuals enduring the condition for over six months post-COVID, unresponsive to conventional treatments.
The outpatient procedure involves injecting an anesthetic into the stellate ganglion, a cluster of nerves in the neck governing signals to the head, neck, arms, and upper chest.
Administered for chronic pain for decades, the treatment showed promising results in the study, with 22 out of 37 patients reporting improved smell distortion one week after the injection and 18 patients experiencing significant symptom improvement after a month. For those responding positively, a second injection further enhanced results, but effectiveness varied among patients.
Dr. Adam Zoga, who conducted the research, emphasized the life-changing impact of the treatment on patients with severe parosmia affecting their physical and mental well-being. The stellate ganglion block is a 10-minute outpatient procedure guided by CT or ultrasound images, targeting the nerve bundle at the neck's base.
While the injection temporarily causes a droopy eyelid, dilated pupil, and brief vision loss, these symptoms quickly resolve. Patients undergoing the procedure reported relief from parosmia, with some experiencing complete recovery within weeks.
Uncertainty Surrounds Efficacy of Stellate Ganglion Blocks in Treating Parosmia
The efficacy of stellate ganglion blocks in treating parosmia remains unclear, with theories suggesting its potential impact on an overactive sympathetic nervous system during COVID-19 infection. However, the absence of a placebo-controlled group in studies, including the recent research by Dr. Zoga, raises uncertainties about the true effectiveness of the nerve block.
Future research, including a placebo group and objective olfactory testing, is deemed necessary by experts to validate the findings and address study limitations.
While stellate ganglion blocks show promise, the lack of objective measurements and the high number of participants without follow-up data limit the conclusive understanding of their impact on parosmia.
Dr. Sowerby emphasizes the necessity of further research to explore the potential benefits and placebo effects, acknowledging the procedure's low risk and its potential to provide relief, even through a placebo effect, for individuals struggling with parosmia after COVID-19.
As the medical community explores stellate ganglion blocks for parosmia, the need for rigorous studies with objective measurements and control groups becomes increasingly crucial to establish the true efficacy of the procedure and its potential as a viable treatment option.
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