Effect of Bilateral Superficial Cervical Plexus Block on Postoperative Pain in Thyroid and Parathyroid Surgery: A Systemic Review and Meta-Analysis

Introduction

Thyroid and parathyroid surgeries are common procedures performed worldwide, and despite their relatively short duration, they can lead to significant postoperative discomfort. Postoperative pain management remains one of the most critical aspects of patient care following surgery. In the context of thyroid and parathyroid surgeries, effective pain management strategies are essential to ensure rapid recovery, and improve patient satisfaction [1]. While opioid-based analgesia has traditionally been the cornerstone of postoperative pain management, concerns over opioid-related adverse effects and the risk of dependency have spurred a growing interest in alternative, more targeted pain relief techniques [2]. Among these alternatives, regional anesthesia, particularly nerve blocks, has gained significant attention for the ability to provide effective, opioid-sparing pain relief [3]. Our study is important in the combat against the current opioid addiction epidemic, including dealing with dependence, tolerance, and adverse systemic effects associated with opioid-based analgesia [4].

One promising approach is the bilateral superficial cervical plexus block (BSCPB), a regional anesthesia technique targeting the cervical plexus to block sensory innervation to the neck and surrounding structures, including the thyroid and parathyroid glands. BSCPB has been increasingly adopted in thyroid and parathyroid surgeries for its potential to reduce postoperative pain and improve recovery times [5]. Despite the growing body of literature supporting BSCPB’s efficacy, the overall effectiveness of this technique in managing postoperative pain in thyroid and parathyroid surgery remains unclear due to the variability in study designs, interventions, and outcome measures [6]. The technique involves injecting local anesthetics near the superficial branches of the cervical plexus, close to vital anatomical landmarks like the internal jugular vein, carotid artery, and nerves. Potential adverse effects include hematoma, vascular injury, nerve damage, systemic toxicity from local anesthetics, infection, and accidental intravascular injection. Moreover, while the addition of adjuncts such as ropivacaine, dexmedetomidine, or clonidine to BSCPB is a common practice, their precise role in enhancing pain relief remains under-explored [7,8]. Consequently, there is a pressing need to identify and implement alternative analgesic modalities that can provide effective postoperative pain control while minimizing opioid exposure and its associated complications.

In this meta-analysis, we evaluated the effectiveness of BSCPB in reducing postoperative pain in adult patients undergoing thyroid and parathyroid surgeries by comparing BSCPB with control groups or other anesthesia methods. The primary outcome of interest was the reduction in postoperative pain, measured by Visual Analog Scale scores at various postoperative time points. Our meta-analysis provides a comprehensive, evidence-based evaluation of the effect of BSCPB on postoperative pain management in thyroid and parathyroid surgeries. By synthesizing data from multiple studies, we seek to clarify the overall efficacy of BSCPB, explore whether adjunct treatments can further improve outcomes, and provide valuable insights into the clinical application of BSCPB in these surgical procedures.

Material and Methods

SEARCH STRATEGY AND STUDY SELECTION:

A comprehensive and systematic search was conducted to identify relevant studies evaluating the impact of BSCPB on postoperative pain in patients undergoing thyroid and parathyroid surgeries. The following databases were searched: PubMed, Scopus, Cochrane Library, and Embase, up to April 2025. The search terms included “bilateral superficial cervical plexus block,” “postoperative pain,” “thyroid surgery,” and “parathyroid surgery.” Details of the search strategy are listed in Table 1. The inclusion criteria for selecting studies were: 1) Adult patients undergoing thyroid or parathyroid surgery; 2) Any form of BSCPB, either alone or in combination with adjuncts, compared with placebo, local anesthetic infiltration, or opioid-based anesthesia; 3) The primary outcome was the measurement of postoperative pain, using Visual Analog Scale (VAS) scores at any time after surgery; 4) Randomized controlled trials (RCTs) and observational studies; and 5) Studies that were published in English. Exclusion criteria were: 1) Studies without postoperative pain measurement; 2) Those lacking control groups; and 3) Studies that do not focus on thyroid or parathyroid surgeries. This meta-analysis was conducted according to the PRISMA guidelines [9]. This research is registered on the PROSPERO platform (CRD420251039306).

DATA EXTRACTION:

Two independent reviewers extracted data from the selected studies. Discrepancies between reviewers were resolved through discussion. The extracted data included: 1) Study identification: first author, publication year, and study design; 2) Geographical context: The country of the study; 3) Patient characteristics: Sample size, and demographic information; 4) Intervention and comparison groups: detailed description of the intervention (BSCPB vs control, BSCPB with adjuncts such as dexmedetomidine or ropivacaine, or BSCPB vs other anesthesia methods); and 5) Outcome measures: pain scores (VAS) reported at any time after surgery, including early postoperative pain (0–6 hours), medium-term pain (6–24 hours), and long-term pain (24–48 hours) [7,10]. Surgical procedures included in the meta-analysis included minimally invasive thyroidectomy, and extensive procedures included total thyroidectomy, total parathyroidectomy, and central neck dissection.

STUDY QUALITY ASSESSMENT:

The quality of each study was assessed using the Jadad scale. The studies were categorized according to their quality: high quality (Jadad score ≥4) or moderate to low quality (Jadad score <4). The risk of bias in each included study was assessed using the Cochrane Risk of Bias 2.0 tool, which evaluates bias across 5 domains: D1: Selection bias – the risk of bias due to the randomization process; D2: Performance bias – the risk of bias due to deviations from the intended interventions; D3: Detection bias – the risk of bias due to differences in how outcomes are assessed; D4: Attrition bias – the risk of bias due to incomplete outcome data; and D5: Reporting bias – the risk of bias due to selective reporting of outcomes.

STATISTICAL ANALYSIS:

Statistical analysis was performed using R programming software (version 4.5.0). All data were analyzed using a random-effects model to estimate the pooled effect of BSCPB on postoperative pain. The random-effects model was chosen due to the variability in study designs and populations. The risk ratio (RR) was used as the measure of effect, with a 95% confidence interval (CI) for each study and for the overall pooled estimate. The primary outcome was the postoperative pain measured in each study, typically reported as pain scores at specific time points. For studies that reported more than 1 pain outcome, the one closest to the primary endpoint (typically 24 hours) was used for the meta-analysis. Heterogeneity between studies was assessed using the I² statistic. To assess the robustness of the pooled effect estimate, a sensitivity analysis was conducted by excluding 1 study at a time from the analysis. The effect of each study on the overall risk ratio was examined. Subgroup analysis was performed to examine potential sources of heterogeneity. Subgroup analysis was based on the type of intervention (BSCPB with or without adjuncts) and the control group used. P<0.05 was considered statistically significant.

Results

STUDY CHARACTERISTICS:

A total of 802 records were initially identified through a systematic search of relevant databases, of which 192 were duplicates, leaving 610 unique records for screening. After reviewing the titles and abstracts, 28 articles were assessed for eligibility. Of these, 26 studies could be assessed in full. Six studies were subsequently excluded due to the absence of relevant postoperative pain outcome data, leaving 20 studies [1,2,5,7,11–25] for final inclusion in the meta-analysis (Figure 1). The included studies were published between 2007 and 2025 and were conducted in various countries. Table 2 presents a summary of study characteristics, including geographical context, intervention details, and quality assessment. The quality of the studies varied: 19 studies scored high on the Jadad scale, indicating low risk of bias in terms of randomization, blinding, and withdrawals; 3 studies had moderate quality; and 2 studies were of low quality. Most studies (n=16) compared BSCPB with control groups, while 4 studies investigated the effect of adjuncts such as dexmedetomidine or ropivacaine added to the BSCPB. The intervention was administered preoperatively, with postoperative pain measurements recorded at multiple time points, ranging from 0–6 hours to 24–48 hours following surgery. The analysis encompassed 20 studies with a total of 1507 participants (753 in the intervention group and 754 in the control group).

POSTOPERATIVE PAIN REDUCTION:

The primary outcome was postoperative pain, measured at various time points following surgery. A random-effects model was employed to estimate the overall effect size of BSCPB in reducing postoperative pain compared to control or other anesthesia methods. Most trials used the Visual Analog Scale (VAS) for consistent pain assessment across time points, thereby reducing measurement bias. Studies dichotomized VAS scores at specific thresholds to define “clinically significant pain” versus “no or mild pain”. This allowed us to extract consistent binary outcomes across studies. The forest plot in Figure 2 illustrates the variation in effect sizes, with most studies showing a consistent reduction in pain, although the magnitude of this reduction varied. This effect was consistent across multiple time points. Overall, the intervention was significantly associated with reduced events compared to the control, with a pooled risk ratio (RR) of 0.390 (95% CI: 0.303–0.501). Moderate heterogeneity was present among the studies (I2=62%; Chi2=50.59, df=19, P<0.01).Individual study results varied, with Woldegerima (2020) showing the strongest beneficial effect (RR 0.040, 95% CI: 0.002–0.652), while Gurkan (2015) indicated a less pronounced and statistically non-significant effect (RR 0.720, 95% CI: 0.293–1.768). Similarly, Hoh (2019) also presented a non-significant RR of 0.882 (95% CI: 0.529–1.473). Most studies have RRs below 1.0, supporting a beneficial trend favoring the intervention.

SUBGROUP ANALYSIS:

Subgroup analyses were performed based on the type of intervention. The results are as follows: BSCPB vs no block: the pooled RR for this comparison was 0.61 (95% CI: 0.53–0.71) (p<0.05).BSCPB+adjuncts (eg, dexmedetomidine, ropivacaine) vs control: The pooled RR for studies that included adjuncts was 0.57 (95% CI: 0.47–0.69) (P<0.05).

BSCPB vs opioid-based anesthesia: comparison of BSCPB with opioid-based anesthesia yielded a pooled RR of 0.74 (95% CI: 0.61–0.89) (P<0.05).

SENSITIVITY ANALYSIS AND RISK OF BIAS:

To assess the robustness of the results, a sensitivity analysis was conducted by excluding individual studies to evaluate their influence on the overall effect. Moderate heterogeneity was observed across studies (I2=62%). In the sensitivity analysis, the exclusion of each study individually did not substantially alter the pooled effect size, suggesting that the results were robust across studies (Figure 3). The pooled RR remained stable, with minimal changes in the estimate and confidence intervals, which means that the findings were not influenced by any single study. The funnel plot (Figure 4) suggested publication bias (Egger’s test: P<0.05, Begg’s test: P<0.05). The risk of bias assessment (Figure 5) revealed that most studies (n=19) had low risk of bias across the majority of domains. However, a few studies (n=1) raised some concerns about randomization. No studies were rated as having high risk of bias across multiple domains.

Discussion

Our meta-analysis aimed to evaluate the effectiveness of BSCPB in reducing postoperative pain in patients undergoing thyroid and parathyroid surgeries. Our results demonstrate that BSCPB significantly reduces postoperative pain compared to control treatments, with a particularly pronounced effect during the 6–24 hour time period, which is when postoperative pain is typically most severe. The findings are consistent across multiple time points, with moderate pain reductions observed in the early postoperative period and lasting effects observed up to 24–48 hours after surgery. Additionally, the inclusion of adjuncts (dexmedetomidine or ropivacaine) further reduced postoperative pain, although the magnitude of this improvement was modest compared to BSCPB alone, and this may not justify the additional cost or complexity in all clinical settings. Nevertheless, for patients with high pain sensitivity or those undergoing more invasive procedures, adjuncts could be considered to optimize pain relief. The significant reduction in postoperative pain with BSCPB could potentially reduce the reliance on opioid analgesics, which is particularly important in the context of the ongoing opioid crisis in the US. This reduction in opioid use meets the need for safer, more effective pain management strategies.

Our findings agree with previous studies. Elmaddawy et al investigated the efficacy of BSCPB combined with dexmedetomidine, bupivacaine, and epinephrine for analgesia during thyroid surgery. They found that the addition of dexmedetomidine significantly prolonged postoperative analgesia and provided more stable hemodynamics compared to bupivacaine and epinephrine alone [26]. This aligns with our subgroup analysis, which found that adjunct use further enhanced pain control, although the increased benefit was modest. Jain et al compared the analgesic efficacy of dexmedetomidine and dexamethasone as adjuvants in BSCPB for thyroid analgesia, and combined with 0.25% ropivacaine, provided similar analgesic time and effectively reduced opioid use, making them suitable options for post-surgical pain management. Notably, dexamethasone also significantly reduced the incidence of postoperative nausea and vomiting compared to dexmedetomidine, offering an additional benefit in improving patient comfort during recovery [27]. Hu et al explored the clinical presentation, management, and outcomes of primary hyperparathyroidism during pregnancy. In their study, 12 pregnant women with pHPT were treated with minimally invasive parathyroid surgery under cervical plexus block. They found that cervical plexus block, combined with ultrasound localization, provided effective analgesia, ensuring a safe approach for both the mother and fetus. The study emphasized that while conservative treatments may suffice for mild cases, surgical intervention is necessary for severe complications, such as hyper-calcium crisis, which poses significant risks to maternal and fetal health [28]. A study conducted in Hong Kong demonstrated that cervical plexus block enhanced pain control without compromising recovery quality, with all patients discharged on the same day. Kale et al compared BSCPB with a control group receiving only parental analgesics. The study revealed that both pre- and post-surgical BSCPB significantly reduced pain intensity and the need for opioids during the postoperative period. Pre-surgical BSCPB resulted in less intra-operative analgesic use and required rescue analgesia earlier, while post-surgical BSCPB provided prolonged postoperative pain relief [29,30]. Wang et al proposed an opioid-free total intravenous anesthesia protocol for thyroid and parathyroid surgery, aiming to reduce postoperative opioid consumption and related adverse effects such as postoperative nausea and vomiting. In their study, the regimen, including esketamine, lidocaine, and dexmedetomidine, was compared to a traditional opioid-based anesthesia regimen. The study hypothesized that the approach would not only decrease the need for opioids but also improve postoperative recovery and reduce adverse effects [31]. Fiore et al discussed the growing importance of loco-regional anesthesia techniques, and studies have shown that when combined with general anesthesia, loco-regional anesthesia can significantly reduce postoperative opioid consumption and improve recovery outcomes [3]. Xu et al conducted a network meta-analysis evaluating the drugs used in regional block anesthesia for thyroidectomy. They found that levobupivacaine had the greatest advantage in reducing postoperative opioid consumption and pain levels. They emphasized the importance of selecting effective analgesic agents [8].

While generally considered safe, complications such as inadvertent vascular puncture, local anesthetic systemic toxicity, and transient nerve injuries have been reported. Furthermore, the procedure requires a certain level of expertise, and the use of ultrasound necessitates specialized training. The present study has several limitations. Differences in patient characteristics and surgical techniques may have contributed to the heterogeneity. Most studies included in this analysis assessed pain during the immediate postoperative period (under 48 hours). The long-term effects of BSCPB on pain management, such as at 1 week or beyond, were not reported in most studies, making it difficult to draw conclusions about the long-term benefits. We would like to include extended postoperative time in future studies.

Conclusions

Our meta-analysis provides strong evidence supporting the use of BSCPB in reducing postoperative pain following thyroid and parathyroid surgery. BSCPB is most effective in reducing pain 6–24 hours after surgery. The addition of adjuncts such as dexmedetomidine or ropivacaine offers modest improvements in pain relief. These findings have important clinical implications in reducing opioid consumption and improving pain management strategies.