Stellate Ganglion Block for COVID-induced Parosmia

Study Summary

Chronic olfactory dysfunction, both hyposmia and parosmia, from the COVID-19 pandemic is a growing public health crisis with up to 1.2 million people in the United States affected. Olfactory dysfunction impacts one's quality of life significantly by decreasing the enjoyment of foods, creating environmental safety concerns, and affecting one's ability to perform certain jobs. Olfactory loss is also an independent predictor of anxiety, depression, and even mortality. Recent research by our group (unpublished data) and suggests that parosmias, moreso than hyposmias, can result in increased rates of anxiety, depression, and even suicidal ideation. While the pandemic has increased the interest by the scientific community in combating the burgeoning health crisis, few effective treatments currently exist for olfactory dysfunction. 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

Primary Outcome

The primary outcome of the study is to determine the efficacy of a stellate ganglion block (SGB) in improving parosmia-related quality of life compared to a saline injection placebo. The instrument contains 28 total items with each scored on a 5-point Likert scale from 0 (no difficulty) to 4 (complete difficulty or very frequent bother). Higher total scores indicate a greater degree of dysfunction and limitation. The minimal clinically important difference (MCID) for DisODOR being 15 points.

Conditions Studied

Interventions

• DRUG Stellate Ganglion Block
• DRUG Placebo Sham Injection

Study Locations (1)