Stellate Ganglion Block for the Treatment of COVID‐19‐Induced Olfactory Dysfunction: A Prospective Pilot Study

Objective The objective of this study was to explore the safety and feasibility of stellate ganglion blocks (SGBs) to treat persistent COVID‐19‐induced olfactory dysfunction (OD). Secondarily, the goal was to determine effect sizes to plan a future randomized clinical trial. Study Design Prospective case series. Setting Quaternary Care Academic Medical Center. Methods In this single‐arm pilot trial, adult participants with a COVID‐19 diagnosis ≥ 12 months prior to enrollment with OD underwent bilateral SGBs. Subjects were followed for 1 month after completion of SGB. The primary outcome measure was the change in the Clinical Global Impression‐Improvement Scale for smell loss. Secondary outcome measures included changes in the University of Pennsylvania Smell Identification Test (UPSIT) and Olfactory Dysfunction Outcomes Rating (ODOR). Results Twenty participants were enrolled with a mean (SD) age of 46 (11) years and a mean (SD) duration of OD of 21 (5) months. At 1 month, 10 (50%) participants experienced at least slight subjective improvement in their OD, 11 (55%) attained a clinically meaningful improvement in smell identification using the UPSIT, and 7 (35%) achieved a clinically meaningful improvement in olfactory‐specific quality of life (QoL) measured by the ODOR. The median difference between UPSIT scores at baseline and 1 month was 6 (95% confidence interval: 3‐11), exceeding the minimal clinically important difference of 4. There were no serious adverse events. Conclusion Sequential SGBs for COVID‐19‐associated OD were safe and associated with modest improvements in subjective olfaction, odor identification, and olfactory‐specific QoL. A placebo‐controlled trial is warranted to determine the efficacy of SGBs for COVID‐19‐associated OD.