Stellate Ganglion Block for the Treatment of COVID-19−Induced Parosmia, 2025, Farrell et al

[forestglip]

See next post for published paper.
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A double-blind clinical trial of SGB for long COVID-related olfactory dysfunction just posted results on ClinicalTrials.gov:

Stellate Ganglion Block for the Treatment of COVID-19-Induced Parosmia: Double-Blinded, Placebo-Controlled Randomized Clinical Trial

32 patients received treatment and 16 placebo.

For the primary outcome (The Parosmia Olfactory Dysfunction Outcomes Rating (DisODOR) where higher score means greater dysfunction:

SGB group​

Baseline: 63​

1-month: 9​

3-months: 14​

​

Placebo group​

Baseline: 66​

1-month: 9​

3-months: 11​

​

So no benefit there. Virtually no difference in any of the other secondary outcomes, which includes overall long covid symptoms and depression/anxiety questionnaire.

The main difference was that the SGB group reported more adverse events:

​

Side effect	% of stellate ganglion block participants	% of placebo participants
transient voice hoarseness	9/31 (29.03%)	0/16 (0.00%)
nasal congestion	6/31 (19.35%)	0/16 (0.00%)
headache or migraine	5/31 (16.13%)	1/16 (6.25%)
lightheadedness or dizziness	5/31 (16.13%)	1/16 (6.25%)

​

​

 

[Utsikt]

A double-blind clinical trial of SGB for long COVID-related olfactory dysfunction just posted results on ClinicalTrials.gov:

I think it’s this publication:

https://jamanetwork.com/journals/jamaotolaryngology/fullarticle/2834979

Stellate Ganglion Block for the Treatment of COVID-19−Induced Parosmia, 2025, Farrell et al

Stellate Ganglion Block for the Treatment of COVID-19−Induced Parosmia

Spoiler: Authors

Farrell, Nyssa Fox; Crock, Lara W.; Islam, Aseeyah; Adkins, Dean; Peterson, Andrew M.; Kallogjeri, Dorina; Piccirillo, Jay F.

Abstract
Importance
Smell distortion (parosmia) is a symptom of post–COVID-19 condition that persists and has immeasurable detriments on quality of life. To date, a standard criterion for treatment of this bothersome condition has not been identified.

Objective
To determine whether stellate ganglion block (SGB) is effective and safe in improving olfactory dysfunction in patients with persistent COVID-19−induced parosmia.

Design, Setting, and Participants
This was a randomized, double-blinded, placebo-controlled clinical trial conducted from October 2023 to September 2024 at a single center study (the Washington University in St Louis/Barnes Jewish Hospital). A volunteer sample of 192 individuals were screened; 57 were enrolled after meeting eligibility criteria (age 18-70 years with self-reported parosmia of ≥6 months since COVID-19 infection, and a screening score of ≥40 on the Parosmia Olfactory Dysfunction Outcomes Rating [DisODOR] scale). Of 135 excluded, the most common reasons were prior SGB (n = 42) and parosmia resolution or non−COVID-19−induced parosmia (n = 28). Data were analyzed from September to October 2024.

Intervention
Ultrasonography-guided injection of 6 to 8 mL of active mepivacaine, 1%, or saline, 0.9%, at the right or left (randomized 1:1) stellate ganglion was performed by a board-certified anesthesiologist and pain medicine specialist.

Main Outcome and Measure
Between-subject difference of 25% in proportion of responders (defined by a 15-point decrease in DisODOR score) from baseline.

Results
The study evaluated 48 participants, 32 randomized to SGB (median [range] age, 45 [19-64] y; 25 [81%] female), and 16 to placebo (median [SD] age, 45 [26-64] y; 13 [81%] female). Time since COVID-19 infection was similar between groups (SGB, 35.3 vs placebo, 30.6 months; MD = −3.1 months; 95% CI, −10.9 to 3.7). Three-month response rate was 43% (n = 13) for SGB and 38% (n = 6) for placebo (difference, −5%; 95% CI, −32% to 33%). There was no between-group difference in clinical global impression of improvement.

Conclusions and Relevance
This randomized clinical trial found that SGB is not superior to placebo in treating COVID-19−induced parosmia, and thus, should not be recommended as treatment.

Trial RegistrationClinical
Trials.gov Identifier: NCT06253806

Web | JAMA Otolaryngology–Head & Neck Surgery
https://doi.org/10.1001/jamaoto.2025.1304

 

[ChronicallyOverIt]

I think it’s this publication:

https://jamanetwork.com/journals/jamaotolaryngology/fullarticle/2834979

Stellate Ganglion Block for the Treatment of COVID-19−Induced Parosmia, 2025, Farrell et al

Stellate Ganglion Block for the Treatment of COVID-19−Induced Parosmia

Spoiler: Authors

Farrell, Nyssa Fox; Crock, Lara W.; Islam, Aseeyah; Adkins, Dean; Peterson, Andrew M.; Kallogjeri, Dorina; Piccirillo, Jay F.

Abstract
Importance
Smell distortion (parosmia) is a symptom of post–COVID-19 condition that persists and has immeasurable detriments on quality of life. To date, a standard criterion for treatment of this bothersome condition has not been identified.

Objective
To determine whether stellate ganglion block (SGB) is effective and safe in improving olfactory dysfunction in patients with persistent COVID-19−induced parosmia.

Design, Setting, and Participants
This was a randomized, double-blinded, placebo-controlled clinical trial conducted from October 2023 to September 2024 at a single center study (the Washington University in St Louis/Barnes Jewish Hospital). A volunteer sample of 192 individuals were screened; 57 were enrolled after meeting eligibility criteria (age 18-70 years with self-reported parosmia of ≥6 months since COVID-19 infection, and a screening score of ≥40 on the Parosmia Olfactory Dysfunction Outcomes Rating [DisODOR] scale). Of 135 excluded, the most common reasons were prior SGB (n = 42) and parosmia resolution or non−COVID-19−induced parosmia (n = 28). Data were analyzed from September to October 2024.

Intervention
Ultrasonography-guided injection of 6 to 8 mL of active mepivacaine, 1%, or saline, 0.9%, at the right or left (randomized 1:1) stellate ganglion was performed by a board-certified anesthesiologist and pain medicine specialist.

Main Outcome and Measure
Between-subject difference of 25% in proportion of responders (defined by a 15-point decrease in DisODOR score) from baseline.

Results
The study evaluated 48 participants, 32 randomized to SGB (median [range] age, 45 [19-64] y; 25 [81%] female), and 16 to placebo (median [SD] age, 45 [26-64] y; 13 [81%] female). Time since COVID-19 infection was similar between groups (SGB, 35.3 vs placebo, 30.6 months; MD = −3.1 months; 95% CI, −10.9 to 3.7). Three-month response rate was 43% (n = 13) for SGB and 38% (n = 6) for placebo (difference, −5%; 95% CI, −32% to 33%). There was no between-group difference in clinical global impression of improvement.

Conclusions and Relevance
This randomized clinical trial found that SGB is not superior to placebo in treating COVID-19−induced parosmia, and thus, should not be recommended as treatment.

Trial RegistrationClinical
Trials.gov Identifier: NCT06253806

Web | JAMA Otolaryngology–Head & Neck Surgery
https://doi.org/10.1001/jamaoto.2025.1304

This is so weird who is thinking SGB improves Olfactory Dysfunction? Most groups I have seen have been getting this since it supposedly it helps calm the nervous system in turn is supposed to improve quality of life. I’d be much more interested in that outcome measurement

 

[Utsikt]

This is so weird who is thinking SGB improves Olfactory Dysfunction? Most groups I have seen have been getting this since it supposedly it helps calm the nervous system in turn is supposed to improve quality of life. I’d be much more interested in that outcome measurement

From the trial registration:

Persistent symptoms after an acute COVID-19 infection, or "Long COVID" symptoms, have been hypothesized to be a result of sympathetic positive feedback loops and dysautonomia. Stellate ganglion blocks have been proposed to treat this hyper-sympathetic activation by blocking the sympathetic neuronal firing and resetting the balance of the autonomic nervous system.

Studies prior to the COVID-19 pandemic have supported a beneficial effect of stellate ganglion blocks on olfactory dysfunction, and recent news reports and a published case series have described a dramatic benefit in both olfactory function and other long COVID symptoms in patients receiving stellate ganglion blocks.

A previous pilot study using stellate ganglion blocks of 20 participants with persistent COVID-19 olfactory dysfunction resulted modest improvements in subjective olfactory function, smell identification, and olfactory-specific quality-of-life, but it lacked a control group.

Therefore, we propose a double-blinded, placebo-controlled randomized clinical trial assessing the efficacy of a stellate ganglion block versus saline injection in a total of up to 140 participants with persistent COVID-19-associated olfactory dysfunction.

 

[ChronicallyOverIt]

“recent news reports and a published case series have described a dramatic benefit in both olfactory function and other long COVID symptoms in patients receiving stellate ganglion blocks.”


It would be nice if they had measured “other symptoms”. I’d rather have quality of life improvements measured than smell.

 

[Utsikt]

It would be nice if they had measured “other symptoms”. I’d rather have quality of life improvements measured than smell.

They measured Clinical Global Impression, an LC questionnaire with 11 symptoms, HADS, and some other smell-related things. Based on the abstract, I suspect there were no differences between the groups.