Stellate Ganglion Block Therapy for Complex Regional Pain Syndrome: A Systematic Review and Meta-Analysis.

BACKGROUND: Sympathetic ganglion block (SGB) technique is becoming increasingly prevalent in the treatment of complex regional pain syndromes (CRPS). Given the varied reported effectiveness of these techniques and the heterogeneity of treatment regimens, there is an urgent need for consistent and high-quality evidence on the efficacy and safety of such procedures. OBJECTIVES: This study aimed to compare the efficacy of SGB therapy for CRPS-related pain. STUDY DESIGN: A meta-analysis of randomized controlled trials (RCTs). METHODS: PubMed, EMBASE, Web of Science, CINAHL, US National Institutes of Health Clinical Trials Registry, Google Scholar, and Cochrane Library Databases were systematically searched between January 1967 and April 2023. A meta-analysis of the included RCTs on SGB was conducted to evaluate the effectiveness and risk of bias (ROBs) of SGB. RESULTS: After screening 8523 records, 12 RCTs were included in this meta-analysis. Compared with controls, the visual analog pain score decreased by a weighted mean difference (WMD) of -6.24 mm (95% CI, -11.45, -1.03; P = 0.019) in the random-effects model, and the numerical scale score was reduced by a WMD of -1.17 mm (95% CI, -2.42, 0.08; P = 0.067) in the fixed-effects model, indicating a pain relief. The methodological quality of the included RCTs was high, with an average PEDro score of 7.0 (range: 5-9). LIMITATIONS: The number of included trials was limited. CONCLUSIONS: SGB therapy can reduce pain intensity in patients with CRPS with few adverse events. However, owing to the relatively high heterogeneity of the included RCTs, a larger sample of high-quality RCTs is needed to further confirm this conclusion.

Differential posttraumatic stress disorder symptom cluster response to stellate ganglion block: secondary analysis of a randomized controlled trial.

Empirically supported treatments for posttraumatic stress disorder (PTSD) exist, but research suggests these therapies are less effective, acceptable, and feasible to deliver to active duty service members (SMs) compared to civilians. Stellate ganglion block (SGB) procedure, in which a local anesthetic is injected around the cervical sympathetic chain or stellate ganglion to temporarily inhibit sympathetic nervous activity, is gaining popularity as an alternative PTSD treatment in military settings. However, it is unknown whether certain PTSD symptoms are more responsive to SGB than others. The current study involved a secondary analysis of data collected from a previous randomized controlled trial of SGB compared to sham (normal saline) injection (N = 113 SMs). PTSD symptoms were assessed via clinical interview and self-report at baseline and 8 weeks post-SGB or sham. Logistic regression analyses showed that the marked alterations in arousal and reactivity PTSD symptom cluster demonstrated the greatest symptom severity reductions after SGB, relative to sham. The reexperiencing cluster also showed pronounced response to SGB in clinician-rated but not self-reported outcomes. Post-hoc item-level analyses suggested that arousal and reactivity cluster findings were driven by reductions in hypervigilance, concentration difficulties, and sleep disturbance, whereas clinician-rated reexperiencing cluster findings were driven by reductions in physiological reactions to trauma cues, emotional reactions to trauma cues, and intrusions. Our findings align with a burgeoning literature positioning SGB as a potential novel or adjunctive PTSD treatment. Results could guide future hypothesis-driven research on mediators of therapeutic change during SGB for PTSD symptoms in SMs.

Efficacy of ultrasound-guided stellate ganglion block in relieving acute postoperative pain: a systematic review and meta-analysis.

OBJECTIVE: The efficacy of ultrasound-guided stellate ganglion block (SGB) in alleviating postoperative pain remains unclear. This meta-analysis was performed to determine the efficacy of ultrasound-guided SGB in relieving acute postoperative pain in patients undergoing surgery with general anesthesia. METHODS: This systematic review and meta-analysis focused on randomized controlled trials comparing SGB with control or placebo. The primary outcome was the pain score at 24 hours after surgery. A random-effects model was used to calculate the mean difference (MD) or risk ratio with a confidence interval (CI) of 95%. RESULTS: Eight studies involving 470 patients were included in the meta-analysis. The results revealed that ultrasound-guided SGB was significantly associated with a lower pain score at 24 hours after surgery (MD = -0.74; 95% CI = -1.39, -0.08; I2 = 86%; low evidence) and at 8 hours after surgery (MD = -0.65; 95% CI = -1.03, -0.28; I2 = 29%; moderate evidence). CONCLUSION: Ultrasound-guided SGB is effective in alleviating acute postoperative pain. However, considering the limited number of trials performed to date, more large-scale and high-quality randomized controlled trials are required to confirm these findings.

Clinical effect of perioperative stellate ganglion block on mechanical ventilation and respiratory function of elderly patients with septic shock.

BACKGROUND: Here we investigated the effect of a stellate ganglion block on the perioperative mechanical ventilation and postoperative recovery of respiratory function of elderly patients with infectious shock. METHODS: Thirty-six elderly patients with septic shock who underwent emergency general anesthesia at our hospital were randomly divided into treatment (T) and control (C) groups (n = 18 each). Group T received a preoperative stellate ganglion block, whereas group C received normal saline. Procalcitonin and C-reactive protein levels were compared preoperatively and at 1 and 7 days postoperative. Mean arterial pressure, oxygen saturation, and mean pulmonary artery pressure were measured preoperative and postoperative as well as at 1 and 7 days later. A blood gas analysis was performed preoperatively, at the end of the operation, during extubation, and at 1 and 7 days postoperative. Intubation under general anesthesia, the completion of anesthesia, and spontaneous respiratory recovery involve pulmonary dynamic compliance, plateau pressure, and mechanical ventilation. RESULTS: General condition did not differ significantly between groups (P > .05). However, mean arterial pressure at the end of surgery and at 1 and 7 days postoperative were significantly higher in group T versus C (P < .05). Furthermore, mean oxygen saturation at the end of surgery and at 1 and 7 days postoperative was significantly lower in group T versus C (P < .05), while procalcitonin and C-reactive protein levels were significantly lower at 1 and 7 days postoperative. Group T had significantly better arterial partial pressure of carbon dioxide, partial pressure of oxygen, and partial pressure of oxygen/fraction of inspired oxygen than group C at the end of surgery, during extubation, and at 1 and 7 days postoperative (P < .05). CONCLUSION: Group T exhibited superior inflammatory responses and respiratory function. Stellate ganglion block in elderly patients with septic shock reduces inflammation, improves mechanical ventilation perioperatively, and promotes postoperative recovery and respiratory function.

Cease the storm - Successful stellate ganglion block in terminating refractory electrical storm.

An electrical storm also known as a ventricular tachycardia storm (VT storm) tends to recur and form a vicious cycle, eventually leading to a refractory electrical storm, refractory to electrical and pharmacological cardioversion. The treatment of refractory VT storm is challenging. Here we discuss the case of a middle-aged gentleman who presented to our emergency department 6 months apart with a refractory VT storm. When all the anti-arrhythmic agents and multiple cardioversion attempts failed in terminating the storm, we attempted ultrasound-guided stellate ganglion block. On both occasions, it successfully terminated the storm. Hence emergency physicians need to be aware of the right technique and timing of stellate ganglion block and ultrasound-guided needle tracking, as it can be a final rescue technique in treating refractory electrical storm in the emergency department.

Ultrasound-guided stellate ganglion block benefits the postoperative recovery of patients undergoing laparoscopic colorectal surgery: a single-center, double-blinded, randomized controlled clinical trial.

BACKGROUND: With the increasing prevalence of colorectal cancer (CRC), optimizing perioperative management is of paramount importance. This study investigates the potential of stellate ganglion block (SGB), known for its stress response-mediating effects, in improving postoperative recovery. We postulate that preoperative SGB may enhance the postoperative recovery of patients undergoing laparoscopic CRC surgery. METHODS: We conducted a randomized controlled trial of 57 patients undergoing laparoscopic colorectal cancer surgery at a single center. Patients, aged 18-70 years, were randomly assigned to receive either preoperative SGB or standard care. SGB group patients received 10 mL of 0.2% ropivacaine under ultrasound guidance prior to surgery. Primary outcome was time to flatus, with secondary outcomes encompassing time to defecation, lying in bed time, visual analog scale (VAS) pain score, hospital stays, patient costs, intraoperative and postoperative complications, and 3-year mortality. A per-protocol analysis was used. RESULTS: Twenty-nine patients in the SGB group and 28 patients in the control group were analyzed. The SGB group exhibited a significantly shorter time to flatus (mean [SD] hour, 20.52 [9.18] vs. 27.93 [11.69]; p = 0.012), accompanied by decreased plasma cortisol levels (mean [SD], postoperatively, 4.01 [3.42] vs 7.75 [3.13], p = 0.02). Notably, postoperative pain was effectively managed, evident by lower VAS scores at 6 h post-surgery in SGB-treated patients (mean [SD], 4.70 [0.91] vs 5.35 [1.32]; p = 0.040). Furthermore, patients in the SGB group experienced reduced hospital stay length (mean [SD], day, 6.61 [1.57] vs 8.72 [5.13], p = 0.042). CONCLUSIONS: Preoperative SGB emerges as a promising approach to enhance the postoperative recovery of patients undergoing laparoscopic CRC surgery. CLINICAL TRIAL REGISTRATION: ChiCTR1900028404, Principal investigator: Xia Feng, Date of registration: 12/20/2019.

Establishment of stellate ganglion block in mice.

BACKGROUND: There have been no reports on the successful implementation of stellate ganglion block (SGB) in mice. OBJECTIVES: This study aims to investigate a new method for implementing SGB in mice by placing them in a supine position with abducted upper limbs and touching the trachea and sternoclavicular joint with the hand. METHODS: Fifty BABL/C mice, 8-10 weeks, were selected and randomly divided into four groups: control group (n = 5); SGB-R group (n = 15); SGB-L group (n = 15); and SGB-L + R (group n = 15). SGB was administered with 0.15% ropivacaine solution in a volume of 0.1 mL. The control group received equal volumes of saline. Horner's syndrome, heart rate, and complications such as brachial plexus block, vascular injury, pneumothorax, local anesthetic toxicity, and death were observed. RESULTS: Horner's syndrome developed in 100% of SGB surviving mice; no difference was seen in the time to onset (100.4 ± 13.4 vs 96.7 ± 12.4, mean ± SD, seconds) and duration (264.1 ± 40.5 vs 296.3 ± 48.0, mean ± SD, min) of Horner's syndrome in the left and right SGB (P > 0.05). Compared with the control group (722 [708-726], median [IQR], bpm), the heart rate was significantly slowed down in the right SGB (475 [451.5-491], median [IQR], bpm) (P < 0.05). While the heart rate was slowed down after performing the left SGB, the difference was not statistically significant (P > 0.05). The overall complication rate was 18.4%, with a brachial plexus block rate of 12.3%, a vascular injury rate of 4.6%, and a mortality rate of 1.5%, as well as no local anesthetic toxicity (includes bilateral implementation of SGB) or pneumothorax manifestations were found. CONCLUSIONS: This method allows for the successful implementation of SGB in a mouse model.

Continuous stellate ganglion block for ventricular arrhythmias: case series, systematic review, and differences from thoracic epidural anaesthesia.

AIMS: Percutaneous stellate ganglion block (PSGB) through single-bolus injection and thoracic epidural anaesthesia (TEA) have been proposed for the acute management of refractory ventricular arrhythmias (VAs). However, data on continuous PSGB (C-PSGB) are scant. The aim of this study is to report our dual-centre experience with C-PSGB and to perform a systematic review on C-PSGB and TEA. METHODS AND RESULTS: Consecutive patients receiving C-PSGB at two centres were enrolled. The systematic literature review follows the latest Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. Our case series (26 patients, 88% male, 60 ± 16 years, all with advanced structural heart disease, left ventricular ejection fraction 23 ± 11%, 32 C-PSGBs performed, with a median duration of 3 days) shows that C-PSGB is feasible and safe and leads to complete VAs suppression in 59% and to overall clinical benefit in 94% of cases. Overall, 61 patients received 68 C-PSGBs and 22 TEA, with complete VA suppression in 63% of C-PSGBs (61% of patients). Most TEA procedures (55%) were performed on intubated patients, as opposed to 28% of C-PSGBs (P = 0.02); 63% of cases were on full anticoagulation at C-PSGB, none at TEA (P < 0.001). Ropivacaine and lidocaine were the most used drugs for C-PSGB, and the available data support a starting dose of 12 and 100 mg/h, respectively. No major complications occurred, yet TEA discontinuation rate due to side effects was higher than C-PSGB (18 vs. 1%, P = 0.01). CONCLUSION: Continuous PSGB seems feasible, safe, and effective for the acute management of refractory VAs. The antiarrhythmic effect may be accomplished with less concerns for concomitant anticoagulation compared with TEA and with a lower side-effect related discontinuation rate.

The relevance of the superior cervical ganglion for cardiac autonomic innervation in health and disease: a systematic review.

PURPOSE: The heart receives cervical and thoracic sympathetic contributions. Although the stellate ganglion is considered the main contributor to cardiac sympathetic innervation, the superior cervical ganglia (SCG) is used in many experimental studies. The clinical relevance of the SCG to cardiac innervation is controversial. We investigated current morphological and functional evidence as well as controversies on the contribution of the SCG to cardiac innervation. METHODS: A systematic literature review was conducted in PubMed, Embase, Web of Science, and COCHRANE Library. Included studies received a full/text review and quality appraisal. RESULTS: Seventy-six eligible studies performed between 1976 and 2023 were identified. In all species studied, morphological evidence of direct or indirect SCG contribution to cardiac innervation was found, but its contribution was limited. Morphologically, SCG sidedness may be relevant. There is indirect functional evidence that the SCG contributes to cardiac innervation as shown by its involvement in sympathetic overdrive reactions in cardiac disease states. A direct functional contribution was not found. Functional data on SCG sidedness was largely unavailable. Information about sex differences and pre- and postnatal differences was lacking. CONCLUSION: Current literature mainly supports an indirect involvement of the SCG in cardiac innervation, via other structures and plexuses or via sympathetic overdrive in response to cardiac diseases. Morphological evidence of a direct involvement was found, but its contribution seems limited. The relevance of SCG sidedness, sex, and developmental stage in health and disease remains unclear and warrants further exploration.

A Multicenter Study of Stellate Ganglion Block as a Temporizing Treatment for Refractory Ventricular Arrhythmias.

BACKGROUND: Ventricular tachycardia (VT) and ventricular fibrillation (VF) are life-threatening conditions and can be refractory to conventional drug and device interventions. Stellate ganglion blockade (SGB) has been described as an adjunct, temporizing intervention in patients with refractory ventricular arrhythmia. We examined the association of SGB with VT/VF in a multicenter registry. OBJECTIVES: This study examined the efficacy of SGB for treatment/temporization of refractory VT/VF. METHODS: The authors present the first analysis from a multicenter registry of patients treated for refractory ventricular arrhythmia at a clinical site in the Czech Republic and the United States. Data were collected between 2016 and 2022. SGB was performed at the bedside by anesthesiologists and/or cardiologists. Outcomes of interest were VT/VF burden and defibrillations at 24 hours before and after SGB. RESULTS: In total, there were 117 patients with refractory ventricular arrhythmias treated with SGB at Duke (n = 49) and the Institute for Clinical and Experimental Medicine (n = 68). The majority of patients were male (94.0%), were White (87.2%), and had an implantable cardioverter-defibrillator (70.1%). The most common etiology of heart disease was ischemic cardiomyopathy (52.1%), and monomorphic VT was the most common morphology (70.1%). Within 24 hours before SGB (0-24 hours), the median episodes of VT/VF were 7.5 (Q1-Q3: 3.0-27.0), and 24 hours after SGB, the median decreased to 1.0 (Q1-Q3: 0.0-4.5; P < 0.001). At 24 hours before SGB, the median defibrillation events were 2.0 (Q1-Q3: 0.0-8.0), and 24 hours after SGB, the median decreased to 0.0 (Q1-Q3: 0.0-1.0; P < 0.001). CONCLUSIONS: In the largest cohort of patients with treatment-refractory ventricular arrhythmia, we demonstrate that SGB use was associated with a reduction in the ventricular arrhythmia burden and need for defibrillation therapy.

Safety and Efficacy of Ultrasound-Guided Sympathetic Blockade by Proximal Intercostal Block in Electrical Storm Patients.

BACKGROUND: Electrical storm (ES) patients who fail standard therapies have a high mortality rate. Previous studies report effective management of ES with bedside, ultrasound-guided percutaneous stellate ganglion block (SGB). We report our experience with sympathetic blockade administered via a novel alternative approach: proximal intercostal block (PICB). Compared with SGB, this technique targets an area typically free of other catheters and support devices, and may pose less strict requirements for anticoagulation interruption, along with lower risk of focal neurological side effects. OBJECTIVES: The authors sought to describe the safety and efficacy of PICB in patients with refractory ES. METHODS: We reviewed our institutional data on ES patients who underwent PICB between January 2018 and February 2023 to analyze procedural safety and short- and long-term outcomes. RESULTS: A total of 15 consecutive patients with ES underwent PICB during this period. Of those, 11 patients (73.3%) were maintained on PICB alone, and 4 patients (26.6%) were maintained on combined block with SGB and PICB. Overall, 72.7% patients who were maintained on PICB alone and 77.8% patients who were maintained on bilateral PICB had excellent arrhythmia suppression. After PICB, implantable cardioverter-defibrillator therapies were significantly reduced (P < 0.05), with 93.3% of patients receiving PICB having no implantable cardioverter-defibrillator shock until discharge or heart transplant. Anticoagulation was continued in all patients and there were no procedure-related complications. Apart from mild transient neurological symptoms seen in 3 patients, no significant neurological or hemodynamic sequelae were observed. CONCLUSIONS: In patients with refractory ES, continuous PICB provided safe and effective sympathetic block (77.8% ventricular arrhythmia suppression), achievable without interruption of anticoagulation, and without significant side effects.

Stellate Ganglion Destruction With Alcohol Versus Thermal Ablation for Chronic Post-Mastectomy Pain: A Randomized Trial.

BACKGROUND: Post-mastectomy pain syndrome (PMPS) is a persistent post-surgical neuropathic pain. Stellate ganglion (SG) block is used for diagnosis, prognosis, and treatment of pain syndrome. OBJECTIVES: We aimed to evaluate the efficacy of SG destruction with alcohol versus thermal ablation for PMPS management. STUDY DESIGN: Randomized, double-blind clinical trial. SETTING: National Cancer Institute, Cairo University, Egypt. METHODS: Female patients aged 20-65 years who underwent breast cancer surgery and suffered moderate to severe pain for more than 6 months were categorized equally into 2 groups. SG destruction was with ultrasound (US) guidance and C7 level confirmation by fluoroscopy either by alcohol injection in Group A or thermal ablation with a time of 60 seconds at 80ºC repeated twice in Group B. Follow-up was at 1, 4, 8, and 12 weeks. RESULTS: Visual analog scale (VAS) measurements after 1, 4, 8, and 12 weeks were significantly lower than pre-procedure measurements in both groups (P value < 0.001). There was a significant reduction in VAS score after 4 and 8 weeks in Group A than in Group B (P value = 0.003 and 0.018). Oxycodone and pregabalin consumption after 4 and 8 weeks were significantly lower in Group A than in Group B. Physical health, mental health, and satisfaction scores were comparable. There were no significant complications in both groups. LIMITATIONS: The relatively small sample size and short follow-up period are limitations to our study. CONCLUSION: US-guided SG destruction with alcohol was more effective than thermal radiofrequency for managing acute postoperative pain by decreasing pain score, oxycodone, and pregabalin consumption, which were consumed before the block.

Prospective study on ultrasound-guided stellate ganglion block improves cerebral blood flow in patients with stroke.

OBJECTIVES: The effect of routine internal medicine and stroke rehabilitation treatment was not good. To confirm that ultrasound-guided stellate ganglion block (SGB) can improve cerebral blood flow in patients with stroke, Transcranial Doppler (TCD) and carotid ultrasound were used to monitor the cerebral blood flow parameters of ultrasound-guided SGB in patients with stroke. METHODS: A prospective study of 40 patients with stroke from January 2021 to October 2022 randomly divided into two groups (group SGB: undergoing ultrasound-guided SGB and standard medical procedures, control group: undergoing standard medical procedures) with 20 cases in each was conducted in People's Hospital of Chongqing Liang Jiang New Area. TCD and carotid artery ultrasound were monitored before and after treatment. There were no significant differences in general data on age, gender, disease course, and stroke type between two groups (P>0.05). RESULTS: After treatment, the bilateral ACA Vm of group SGB was significantly higher, the bilateral internal carotid artery RI and left VA RI were significantly lower than in control group (P<0.05). In group SGB, the Vm of bilateral MCA, bilateral PCA, right ACA, bilateral VA, and BA after treatment were significantly (P<0.05) increased compared to before treatment. PI of bilateral MCA, right ACA, and left VA after treatment were significantly (P<0.05) decreased compared to before treatment. RI of bilateral MCA, bilateral PCA, and bilateral VA after treatment were significantly (P<0.05) decreased compared to before treatment. Right internal carotid artery D after treatment was significantly (P<0.05) higher than before treatment. RI of bilateral internal carotid artery after treatment was significantly (P<0.05) lower than before treatment. CONCLUSIONS: Ultrasound-guided stellate ganglion block could improve local cerebral blood flow and vascular compliance in patients with stroke, and reduce vascular resistance.

Electrical storm treatment by percutaneous stellate ganglion block: the STAR study.

BACKGROUND AND AIMS: An electrical storm (ES) is a clinical emergency with a paucity of established treatment options. Despite initial encouraging reports about the safety and effectiveness of percutaneous stellate ganglion block (PSGB), many questions remained unsettled and evidence from a prospective multicentre study was still lacking. For these purposes, the STAR study was designed. METHODS: This is a multicentre observational study enrolling patients suffering from an ES refractory to standard treatment from 1 July 2017 to 30 June 2023. The primary outcome was the reduction of treated arrhythmic events by at least 50% comparing the 12 h following PSGB with the 12 h before the procedure. STAR operators were specifically trained to both the anterior anatomical and the lateral ultrasound-guided approach. RESULTS: A total of 131 patients from 19 centres were enrolled and underwent 184 PSGBs. Patients were mainly male (83.2%) with a median age of 68 (63.8-69.2) years and a depressed left ventricular ejection fraction (25.0 ± 12.3%). The primary outcome was reached in 92% of patients, and the median reduction of arrhythmic episodes between 12 h before and after PSGB was 100% (interquartile range -100% to -92.3%). Arrhythmic episodes requiring treatment were significantly reduced comparing 12 h before the first PSGB with 12 h after the last procedure [six (3-15.8) vs. 0 (0-1), P < .0001] and comparing 1 h before with 1 h after each procedure [2 (0-6) vs. 0 (0-0), P < .001]. One major complication occurred (0.5%). CONCLUSIONS: The findings of this large, prospective, multicentre study provide evidence in favour of the effectiveness and safety of PSGB for the treatment of refractory ES.

Stellate ganglion block for treating post-COVID-19 parosmia.

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.