Stellate ganglion block for treating post‐COVID‐19 parosmia

Abstract Background Post‐COVID parosmia may be due to dysautonomia and sympathetic hyperresponsiveness, which can be attenuated by stellate ganglion block (SGB). This study evaluates SGB as a treatment for post‐COVID olfactory dysfunction (OD). Methods Retrospective case series with prospective data of patients with post‐COVID OD undergoing unilateral (UL) or bilateral (BL) SGB. Patients completed Brief Smell Identification Tests (BSIT) (12 points maximum) and post‐procedure surveys including parosmia severity scores on a scale of 1 (absent) to 10 (severe). Scores were compared from before treatment (pre‐SGB) to after first (SGB1) or second (SGB2) treatments in overall, UL, and BL cohorts. Results Forty‐seven patients with post‐COVID OD underwent SGB, including 23 UL and 24 BL. Twenty patients completed pre‐ and post‐SGB BSITs (eight UL and 12 BL). Twenty‐eight patients completed postprocedure surveys (11 UL and 17 BL). There were no differences in BSIT scores from pre‐SGB to post‐SGB1 or post‐SGB2 for the overall ( p = 0.098), UL ( p = 0.168), or BL ( p = 0.230) cohorts. Parosmia severity for the overall cohort improved from pre‐SGB (8.82 ± 1.28) to post‐SGB1 (6.79 ± 2.38) and post‐SGB2 (5.41 ± 2.35), with significant differences from pre‐SGB to post‐SGB1 ( p < 0.001) and pre‐SGB to post‐SGB2 ( p < 0.001), but not post‐SGB1 to post‐SGB2 ( p = 0.130). Number of parosmia triggers decreased for overall ( p = 0.002), UL ( p = 0.030) and BL ( p = 0.024) cohorts. Quality of life (QOL) improved for all cohorts regarding food enjoyment, meal preparation, and socialization ( p < 0.05). Conclusion SGB may improve subjective parosmia and QOL for patients with post‐COVID OD, however it may not affect odor identification. Further placebo‐controlled studies are warranted.