Stellate Ganglion Block Fails to Improve COVID-Related Smell Distortion: JAMA
A new study published in the Journal of American Medical Association showed that stellate ganglion block did not reduce COVID-19-induced odor distortion.
A persistent symptom of the post-COVID-19 syndrome that has an incalculable negative impact on quality of life is smell distortion, or parosmia. There is currently no accepted standard for treating this annoying illness. Thus, to ascertain if stellate ganglion block (SGB) is safe and successful in resolving olfactory impairment in individuals with chronic COVID-19-induced parosmia, Nyssa Fox Farrell and colleagues undertook this investigation.
The trial took place at Barnes Jewish Hospital and Washington University in St. Louis between October 2023 and September 2024. A total of 192 volunteers were screened, where 57 were included after fulfilling the eligibility requirements, which included being between the ages of 18 and 70, having self-reported parosmia that occurred at least 6 months following COVID-19 infection, and having a screening score of at least 40 on the Parosmia Olfactory Dysfunction Outcomes Rating [DisODOR] scale. The most frequent explanations for the exclusion of 135 were previous SGB (n = 42) and parosmia resolution or non-COVID-19-induced parosmia (n = 28).
A board-certified anesthesiologist and pain medicine expert administered 6 to 8 mL of active mepivacaine, 1%, or saline, 0.9%, by ultrasound-guided injection at the right or left (randomized 1:1) stellate ganglion. 25% difference between subjects in the percentage of respondents who dropped their DisODOR score by 15 points from the baseline was considered as the primary outcome.
32 people were randomly assigned to SGB (median [range] age, 45 [19-64] years; 25 [81%] female) and 16 were assigned to placebo (median [SD] age, 45 [26-64] years; 13 [81%] female) out of the 48 persons examined in the research. Both groups had comparable times after COVID-19 infection (SGB, 35.3 vs. placebo, 30.6 months; MD = -3.1 months; 95% CI, -10.9 to 3.7).
For SGB, the 3-month response rate was 43% (n = 13), while for the placebo, it was 38% (n = 6; difference, −5%; 95% CI, −32% to 33%). There was no difference in the clinical overall perception of improvement across the groups. Overall, in accordance with the results of this research, SGB is not a better therapy for COVID-19-induced parosmia than a placebo, and as such, it should not be suggested.
Source:
Farrell, N. F., Crock, L. W., Islam, A., Adkins, D., Peterson, A. M., Kallogjeri, D., & Piccirillo, J. F. (2025). Stellate ganglion block for the treatment of COVID-19-induced parosmia: A randomized clinical trial. JAMA Otolaryngology-Head & Neck Surgery. https://doi.org/10.1001/jamaoto.2025.1304
