Effects of stellate ganglion block anesthesia on cognition and biomarkers in patients undergoing gastrointestinal surgery

Abstract

BACKGROUND

Surgery is a common treatment for gastrointestinal tumors. General anesthesia (GA), while effective, can cause oxidative stress reactions and neuroinflammation, potentially leading to postoperative cognitive dysfunction and gastrointestinal dysfunction. The stellate ganglion block (SGB) can reduce sympathetic excitability and stress responses. This study aims to investigate whether combining SGB with GA can mitigate these adverse effects in patients undergoing gastrointestinal surgery.

AIM

To analyze the effects of SGB plus GA on hemodynamic stability, oxidative stress, neuroinflammation, cognitive function, and gastrointestinal function in patients undergoing gastrointestinal surgery.

METHODS

Patients undergoing gastrointestinal surgery between October 2022 and December 2024 were divided into two groups: A single GA group and an SGB combined with GA group (40 patients each). Hemodynamics, oxidative stress response, laboratory indices, cognitive function, and gastrointestinal function were compared preoperatively and 24 hours postoperatively between the two groups. Pain levels and complications were also recorded.

RESULTS

Before anesthesia induction, no significant differences were found in various indexes (including hemodynamics, oxidative stress indicators, laboratory indices, cognitive function scores, and gastrointestinal function indicators) between the two groups (P > 0.05). At tracheal intubation, 3 minutes after, and extubation, the GA-only group had significantly higher mean arterial pressure and heart rate postoperatively than preoperatively and compared to the SGB-GA combined group (P < 0.05). Twenty-four hours postoperatively, oxidative stress indicators (malondialdehyde and nitric oxide) were significantly higher and superoxide dismutase was significantly lower in the GA group than in the SGB-GA combined group (P < 0.05). Cognitive function scores [Mini-Mental State Examination and Montreal Cognitive Assessment (MoCA)] and gastrointestinal function indicators (motilin) were also significantly better in the SGB-GA combined group (P < 0.05). The 24-hour postoperative MoCA score was 0.98 points higher in the SGB-GA combined group. No significant differences were found in the time of first postoperative ambulation, catheter removal time, and 24-hour postoperative pain between groups (P > 0.05).

CONCLUSION

Combining SGB with GA can maintain perioperative hemodynamic stability, reduce oxidative stress and neuroinflammatory injury, and attenuate postoperative cognitive decline and gastrointestinal dysfunction in patients undergoing gastrointestinal surgery.

Key Words: Stellate ganglion block anesthesia; Gastrointestinal surgery; Hemodynamics; Oxidative stress; Cognitive function; Gastrointestinal function

Core Tip: Stellate ganglion block (SGB) anesthesia has remarkable advantages when used in gastrointestinal surgery. In contrast to general anesthesia, SGB effectively stabilizes patient hemodynamics throughout the perioperative phase. Our results showed that using SGB significantly reduced oxidative stress, as evidenced by lower levels of related biomarkers. This not only safeguards cognitive function, but also actively promotes the recovery of gastrointestinal function, presenting a more optimal choice for enhancing patient management and postoperative outcomes.

INTRODUCTION

Gastrointestinal surgery is the main method for treating gastrointestinal tumors with the aim of removing lesions, controlling the disease, and improving the quality of life of patients[1]. To ensure effectiveness, such surgeries require professional doctors to perform standardized surgical operations but also requires rational selection of anesthesia methods to improve the feasibility and safety of the surgery. General anesthesia (GA) is commonly used in gastrointestinal surgery. This method has a definite effect and can ensure that patients are unconscious during surgery, providing them with a complete anesthesia experience[2]. However, operations and concomitant procedures such as laryngoscope exposure and tracheal intubation can cause oxidative stress reactions in patients, leading to changes in blood pressure and heart rate, and increasing the risk of hemodynamic fluctuations. Moreover, the use of GA can lead to neuroinflammation, cause central nervous system damage, and induce or exacerbate postoperative cognitive dysfunction[3].

The stellate ganglion block (SGB) is a sympathetic nerve block. Drugs injected into the stellate ganglion infiltrate and block sympathetic activity in the innervated area. Compared with GA, this method can reduce the excitability of the sympathetic nerves, reduce the body's stress response, relieve pain, and maintain the stability of the body's internal environment[4,5]. Previous studies have shown that SGB can effectively reduce sympathetic over-activation and catecholamine release, thereby reducing systemic inflammatory response and oxidative stress levels[4]. It can also regulate immune function and inhibit the production and release of pro-inflammatory factors, such as IL-6 and TNF-α[4]. Additionally, SGB can improve cerebral blood flow and oxygen supply to alleviate ischemia-reperfusion injury[4]. These findings suggest that SGB may have a protective effect on cognitive function by reducing neuroinflammation and neuronal damage. However, the application of SGB in gastrointestinal surgery remains underexplored, and its effects on postoperative cognitive function and oxidative stress in this context are not well understood.

To clarify the application value of SGB anesthesia in gastrointestinal surgery, this study included 80 patients undergoing gastrointestinal surgery as the research participants and summarized and compared the effects of GA alone and GA combined with SGB anesthesia. The primary aim of this study was to investigate whether combining SGB with GA would reduce postoperative cognitive impairment and oxidative stress compared to GA alone. We hypothesized that SGB combined with GA would maintain perioperative hemodynamic stability, reduce oxidative stress and neuroinflammatory damage, and improve postoperative cognitive function and gastrointestinal recovery in patients undergoing gastrointestinal surgery.

MATERIALS AND METHODS

General information

This study was approved by the Ethics Committee of The Third Affiliated Hospital of Nanchang University, The First Hospital of Nanchang (No. IIT2025009) and conducted in strict accordance with the principles of the Declaration of Helsinki. All outcome assessors were blinded to group assignments (assessor-blinded). Patients scheduled to undergo elective laparoscopic radical resection of gastrointestinal tumors at our hospital between October 2022 and October 2024 were enrolled. The sample size calculation was based on preliminary data, which indicated an approximate 1.0-point difference in the Montreal Cognitive Assessment (MoCA) scores at 24 hours postoperatively, with a standard deviation of approximately 1.2. Assuming a two-sided α = 0.05 and β = 0.20 (80% power), at least 36 patients per group were required. To account for potential dropouts, the final sample size was set at 40 patients per group. The patients were divided into control and observation groups according to the method of anesthesia, with 40 patients in each group.

The control group comprised 23 males and 17 females, aged 22 to 85 years, with an average age of 64.78 ± 6.12 years. The body mass index (BMI) ranged from 18 to 26 kg/m² (average: 22.18 ± 1.21 kg/m²). According to the American Society of Anesthesiologists (ASA) anesthesia grade, 27 patients had grade II disease, and 13 had grade III disease. The disease types included gastric cancer in 21 patients, rectal cancer in 10, and colorectal cancer in 9. The observation group comprised 21 males and 19 females, aged 25 to 85 years, with an average age of 62.12 ± 6.27 years. The BMI ranged from 19 to 25 kg/m² (average: 22.16 ± 1.24 kg/m²). According to the ASA anesthesia grade, 30 patients had grade II and 10 had grade III disease. Eighteen patients had gastric cancer, 12 had rectal cancer, and 10 had colorectal cancer. There were no statistically significant differences between the two groups in age, BMI, type of cancer, and anesthesia grade (P > 0.05).

The inclusion criteria were as follows: (1) All patients had gastrointestinal tumors and could tolerate surgical operations; (2) Age > 20 years; (3) ASA anesthesia grades II-III; (4) Underwent laparoscopic radical resection by the same medical team; (5) Sufficient data to provide information support for the study; and (6) Signed informed consent.

The exclusion criteria were as follows: (1) Patients with severe abnormalities in heart, brain, liver, and kidney functions; (2) Patients with immune or blood system diseases; (3) Patients with other types of malignant tumors; (4) Patients with mental diseases; (5) Women who were preparing for pregnancy or who were pregnant or breastfeeding; (6) Those with a history of abdominal trauma or surgery; and (7) Those with contraindications to SGB anesthesia.

Study design and blinding

This study was not randomized, but efforts were made to ensure that the two groups were comparable in terms of baseline characteristics. Blinding was implemented for outcome assessors, particularly those evaluating cognitive function using the Mini-Mental State Examination (MMSE) and MoCA scores, to minimize bias. All outcome assessors were blinded to group assignments.

Ethics approval and compliance

The study adhered to international ethical standards and was approved by the Institutional Review Board of Nanchang First Hospital (Approval number: IIT2025009). The study was conducted in accordance with the principles of the Declaration of Helsinki. All participants or their legal guardians provided written informed consent prior to enrollment.

Methods

GA alone group (control group): The control group received GA. The patients were admitted to the operating room, and the electrocardiogram, blood pressure, heart rate, oxygen saturation, and bispectral index of the electroencephalogram were monitored in real-time. Intravenous access was established, and compound sodium chloride injection was infused at a rate of 5 mg/kg/hour to maintain acid-base balance. Antibiotics were prophylactically used according to the physician's advice. All patients underwent intravenous anesthesia induction (0.3 μg/kg succinylfentanyl citrate injection, 0.3 mg/kg etomidate injection, and 0.3 mg/kg cis-arcumaxine injection). After tracheal intubation, the patients were connected to an anesthesia machine. The respiratory parameters were set as follows: Airway pressure < 25 mmHg and end-tidal carbon dioxide partial pressure 35 mmHg ≤ PetCO₂ ≤ 45 mmHg. Propofol and remifentanil hydrochloride were continuously administered via injection. During the anesthesia induction and maintenance process, the bispectral index of the electroencephalogram was maintained between 40 and 60. When the mean arterial pressure of the patient exceeded 20% of the baseline value and the heart rate exceeded 100 c/minute, the depth of anesthesia was adjusted, and 12.5 mg urapidil hydrochloride was administered via injection if necessary. When the decrease in mean arterial pressure exceeded 20% of the baseline value, the depth of anesthesia was adjusted, the infusion rate was increased, and a 2-5 mg dopamine hydrochloride injection was administered if necessary. For situations in which the heart rate was < 45 beats/minute or the circulation was unstable, the patient was carefully observed for visceral traction. If traction was present, surgical stimulation was suspended, the depth of anesthesia was appropriately adjusted, and a 0.5 g atropine sulfate injection was administered if necessary.

SGB combined with GA group (observation group): The observation group received GA combined with SGB. The SGB procedure was performed by attending anesthesiologists who were qualified for ultrasound-guided interventional surgeries and had completed special training in SGB (> 50 cases). The SGB anesthesia protocol was as follows: The patient was placed in the supine position, and a small pillow was placed under the right shoulder. The medial edge of the sternocleidomastoid muscle was identified at the cricoid cartilage notch and the position marked. A portable color Doppler ultrasonic diagnostic instrument (Shenzhen Huasheng Medical Technology Co. Ltd. Registration number: Yue Jie Zhun 20152231208 Model specification: Clover 50) was used, and a high-frequency probe was transversely placed at the marked site. The puncture was performed under ultrasonic guidance. A 25 G, 6-cm puncture needle was inserted into the anterior lateral side of the right neck. Using the ultrasonic probe, the physicians confirmed that the needle tip was located in front of and outside the C6 transverse process, in front of the longus colli muscle, and behind the carotid artery, and that there was no blood return. Seven milliliters of ropivacaine hydrochloride was injected. The puncture needle was removed and a dressing was applied to the puncture site. The ipsilateral (side of the block) eyelid appearing smaller, upper eyelid ptosis, a ‘sunken’ appearance of the eye, pupil constriction (miosis), and a lack of facial perspiration (anhidrosis) indicated successful SGB anesthesia. These characteristics are collectively referred to as Horner syndrome.

Observation indicators

Perioperative hemodynamics: A bedside monitor (Manufacturer: Nihon Kohden, Tokyo, Japan; Registration Certificate Number: Hu-Armoured 20202070210, Model Specification: PVM-2701) was used to monitor the systolic and diastolic blood pressure, and heart rate of the control and observation groups before anesthesia induction, during tracheal intubation, 3 minutes after tracheal intubation, and during extubation. The mean arterial pressure and heart rate during these periods were compared between the two groups. The mean arterial pressure is calculated using the following formula: Systolic blood pressure + 2 × diastolic blood pressure/3.

Oxidative stress response: Fasting venous blood (5 mL) was collected from each patient before anesthesia induction and 24 hours after surgery and subsequently placed in a medical centrifuge (Manufacturer: Changzhou Weierkang Medical Technology Co., Ltd., Changzhou, Jiangsu Province, China; Record Number: Su Chang-Armoured 20220378, Model Specification: H1650). The centrifugation parameters were as follows: Speed 3500 rpm, time 5 minutes, and radius 12 cm. The upper layer of the serum was collected, and the nitric oxide (NO) level was detected by the modified nitrate reduction method using an automatic biochemical analyzer (Manufacturer: Wuhan Shangyi Kangjian Technology Co., Ltd., Wuhan, Hubei Province, China; Registration Certificate Number: E-Armoured 20182222359, KEA-TR100). The malondialdehyde (MDA) and superoxide dismutase (SOD) levels were determined using a colorimetric method.

Laboratory indexes: According to the above method, fasting venous blood was collected from the two groups before anesthesia induction and 24 hours after surgery and subsequently centrifuged. An automatic chemiluminescence immunoassay analyzer (Manufacturer: Changde Pushikang Biotechnology Co., Ltd., Changde, Hunan Province, China; Registration Certificate Number: Xiang-Armored 20212221925, Model Specification: HMI680) was used to detect the levels of serum β-amyloid peptide 42 (Aβ-42), interleukin-6 (IL-6), and tau-181 protein using the double-antibody sandwich enzyme-linked immunosorbent assay method.

Cognitive function: Research nurses who received unified training and were unaware of group allocations evaluated the patients for cognitive function in a separate isolated quiet room using standardized instructions before anesthesia induction and 24 hours after surgery. The cognitive function was evaluated according to the MMSE and MoCA scores[6,7]. The lowest score of the MMSE is 0, and the highest score is 30. Scores between 24-30 indicate normal cognitive function.

Gastrointestinal function: Two groups of fasting venous blood samples were collected before anesthesia induction and 24 hours postoperatively according to the above mode and subsequently centrifuged. The levels of motilin and vasopeptides were detected using a fully automatic biochemical analyzer.

Safety indicators: The occurrence of complications related to SGB procedures, such as recurrent laryngeal nerve block, brachial plexus nerve block, pneumothorax, local hematoma, and local anesthetic poisoning, as well as the time of first postoperative ambulation (out of bed), the time of catheter removal, and the postoperative 24-hour pain score [visual analog scale (VAS)], were observed and recorded.

Statistical analysis

Data processing software SPSS 22.0 was used for analyses. Before conducting parametric tests, the Shapiro-Wilk normality test was performed to confirm the normal distribution of the data. Measures that conformed to a normal distribution were analyzed using mean ± SD and t-tests. Multiple time-point measurements were subjected to a repeated-measures analysis of variance (ANOVA). To control for the risk of multiple comparisons and reduce Type I error risk, Bonferroni correction (corrected α = 0.05/5 = 0.01) was applied to the between-group comparisons of key outcome measures (MMSE, MoCA, IL-6, Aβ-42, tau-181). The mean differences (MD) and their 95% confidence intervals (95%CIs) were determined for the key outcomes. Statistical significance was considered at P < 0.05. Additionally, effect sizes were calculated for key comparisons to enhance the interpretability of the results.

RESULTS

Hemodynamics

The mean arterial pressure and heart rate before anesthesia induction were consistent among the groups (P > 0.05). During tracheal intubation, 3 minutes after intubation, and at extubation, the mean arterial pressure and heart rate in the GA-only group were significantly higher than those in the SGB-GA combined group (P < 0.05). Repeated-measures ANOVA showed significant differences in group, time, and interaction effects (P < 0.001). These findings indicate that combining SGB with GA effectively stabilizes hemodynamics during critical perioperative periods (Table 1).

Table 1 Hemodynamic parameters before and after anesthesia induction (mean ± SD).

Group	Case	MABP (mmHg)				Heart rate (beats/minute)
		Time 1	Time 2	Time 3	Time 4	Time 1	Time 2	Time 3	Time 4
Control	40	89.21 ± 9.12	100.56 ± 8.72a	102.18 ± 9.24a	97.60 ± 8.78a	86.27 ± 8.56	91.12 ± 9.32a	96.78 ± 8.96a	91.62 ± 9.18a
Observation	40	89.32 ± 9.16	90.18 ± 10.44	91.27 ± 8.52	90.84 ± 9.18	86.12 ± 8.78	86.72 ± 9.27	87.16 ± 9.18	86.54 ± 9.72
t value		0.054	4.826	5.490	3.366	0.077	2.117	4.743	2.403
P value		0.957	< 0.001	< 0.001	0.001	0.939	0.037	< 0.001	0.019

^aP < 0.05 compared with the pre-anesthesia induction in the same group.

Repeated-measures ANOVA showed significant inter-group, time, and interaction effects for mean arterial pressure and heart rate (P < 0.001). MABP: Mean arterial blood pressure.

Oxidative stress response

There was no significant difference in oxidative stress indicators between the two groups before anesthesia induction (P > 0.05). Twenty-four hours postoperatively, MDA and NO levels were significantly higher in both groups compared to preoperative levels (P < 0.05), while SOD levels were significantly lower (P < 0.05). However, the SGB-GA combined group had significantly lower MDA and NO levels and higher SOD levels compared to the GA-only group (P < 0.05). This suggests that SGB reduces oxidative stress in the perioperative period (Table 2).

Table 2 Oxidative stress indicators before and 24 hours after surgery (mean ± SD).

Group	Case	MDA (nmol/L)		NO (nmol/mL)		SOD (U/mL)
		Before induction of anesthesia	24 hours after surgery	Before induction of anesthesia	24 hours after surgery	Before induction of anesthesia	24 hours after surgery
Control	40	4.72 ± 0.42	5.78 ± 0.36a	35.56 ± 5.21	55.60 ± 7.72a	30.16 ± 4.32	23.27 ± 3.68a
Observation	40	4.78 ± 0.45	5.21 ± 0.48a	35.78 ± 5.32	43.21 ± 6.54a	30.24 ± 4.35	27.12 ± 4.21a
t value		0.616	6.008	0.187	7.745	0.083	4.355
P value		0.539	0.008	0.852	< 0.001	0.934	< 0.001

^aP < 0.05 compared with that before anesthesia induction in the same group.

MDA: Malondialdehyde; NO: Nitric oxide; SOD: Superoxide dismutase.

Laboratory indicators

Preoperative levels of serum Aβ-42, IL-6, and tau-181 protein did not differ significantly between the groups (P > 0.05). Postoperatively, these markers were elevated in both groups, but the increases were significantly lower in the SGB-GA combined group compared to the GA-only group (P < 0.05). The inter-group differences (MD) and 95%CIs were as follows: Aβ-42, -5.05 ng/L (95%CI: -8.20 to -1.90); IL-6, -2.92 pg/mL (95%CI: -3.84 to -2.00); and tau-181, -2.09 ng/L (95%CI: -3.41 to -0.77). These results indicate that SGB reduces neuroinflammation and neuronal damage (Table 3).

Table 3 Laboratory indicators before and 24 hours after surgery (mean ± SD, ng/L).

Group	Case	Aβ-42		IL-6		tau-181 protein
		Before induction of anesthesia	24 hours after surgery	Before induction of anesthesia	24 hours after surgery	Before induction of anesthesia	24 hours after surgery
Control	40	55.86 ± 6.72	65.21 ± 7.18a	7.42 ± 1.18	13.24 ± 2.16a	9.56 ± 2.16	16.27 ± 3.25a
Observation	40	56.18 ± 6.54	60.16 ± 6.86a	7.36 ± 1.21	10.32 ± 1.54a	9.52 ± 2.24	14.18 ± 2.72a
t value		0.216	3.216	0.225	6.962	0.081	3.119
P value		0.830	0.002	0.823	< 0.001	0.935	0.003

^aP < 0.05 compared with the pre-anesthesia induction in the same group.

After Bonferroni correction, the differences between interleukin-6 groups remained significant (corrected P < 0.001), while the differences between β-amyloid peptide 42 (corrected P = 0.003) and tau-181 (corrected P = 0.004) were marginally significant (corrected α = 0.01). Aβ-42: Β-amyloid peptide 42; IL-6: Interleukin-6.

Cognitive function

Before anesthesia induction, no significant differences in cognitive function scores were observed between the groups (P > 0.05). At 24 hours postoperatively, both groups exhibited a decline in MMSE and MoCA scores, but the decline was significantly smaller in the SGB-GA combined group compared to the GA-only group (P < 0.05). Specifically, the MoCA score in the SGB-GA combined group was 0.98 points higher than that in the GA-only group (23.78 ± 0.96 vs 22.80 ± 1.12, MD = 0.98, 95%CI: 0.55-1.41). Although this difference did not reach the commonly accepted minimally clinically important difference for MoCA (≥ 2 points), it suggests that SGB has a statistically significant tendency to attenuate cognitive decline in the early postoperative period. This finding, combined with the significant improvements in serum nerve damage markers (Aβ-42, tau-181) and inflammatory factors (IL-6), indicates that SGB may have a protective effect on cognitive function by reducing neuroinflammation and neuronal damage (Table 4).

Table 4 Cognitive function scores before and 24 hours after surgery (mean ± SD, score).

Group	Case	MMSE		MoCA
		Before induction of anesthesia	24 hours after surgery	Before induction of anesthesia	24 hours after surgery
Control	40	27.72 ± 0.98	23.12 ± 0.78a	26.54 ± 1.12	22.80 ± 1.12a
Observation	40	27.54 ± 0.92	24.96 ± 0.84a	26.48 ± 1.16	23.78 ± 0.96a
t value		0.847	10.152	0.235	4.202
P value		0.400	< 0.001	0.815	< 0.001

^aP < 0.05 compared to the pre-anesthesia induction in the same group.

MMSE: Mini-Mental State Examination; MoCA: Montreal Cognitive Assessment.

Gastrointestinal function

Before anesthesia induction, no significant differences in gastrointestinal function were observed between the groups (P > 0.05). Postoperatively, motilin levels significantly decreased and vasoactive peptide levels significantly increased in both groups (P < 0.05). However, the SGB-GA combined group had higher motilin levels and lower vasoactive peptide levels compared to the GA-only group (P < 0.05). This indicates that SGB may help preserve gastrointestinal function by reducing postoperative dysfunction (Table 5).

Table 5 Gastrointestinal function indicators before and 24 hours after surgery (mean ± SD, pg/mL).

Group	Case	Motilin		Vasoactive peptide
		Before induction of anesthesia	24 hours after surgery	Before induction of anesthesia	24 hours after surgery
Control	40	356.72 ± 70.78	221.54 ± 52.18a	10.12 ± 1.32	20.78 ± 3.56a
Observation	40	360.12 ± 72.45	272.32 ± 60.21a	10.27 ± 1.44	16.21 ± 2.80a
t value		0.212	4.031	0.486	6.382
P value		0.832	< 0.001	0.629	< 0.001

^aP < 0.05 compared with the same group before anesthesia induction.

Safety indicators

Within 24 hours after surgery, no complications associated with the SGB procedures (such as recurrent laryngeal nerve block, brachial plexus block, pneumothorax, local hematoma, or local anesthetic toxicity) were observed. There were no significant differences between the groups in the time to first postoperative ambulation, time to catheter removal, or 24-hour postoperative pain score (VAS; P > 0.05; Table 6).

Table 6 Safety indicators (mean ± SD).

Group	Case	First time out of bed (hour)	Time of catheter removal (day)	VAS score 24 hours after surgery (divide)
Control	40	18.15 ± 3.82	12.73 ± 2.97	4.52 ± 1.34
Observation	40	17.32 ± 3.45	11.86 ± 2.54	4.23 ± 1.12
t value		1.021	1.432	1.138
P value		0.310	0.156	0.258

VAS: Visual analog scale.

DISCUSSION

The incidence of gastrointestinal malignancies is currently high, and the number of surgical patients is increasing. Laparoscopic radical resection is the primary surgical method of treatment, and GA is often used during these procedures. While maintaining muscle relaxation, GA can cause stress reactions in patients and lead to postoperative cognitive impairment[8]. Therefore, the selection of anesthetic methods should be carefully considered by clinicians to improve the feasibility and safety of surgery.

The results of this study showed that the mean arterial pressure and heart rate at the time of tracheal intubation, 3 minutes after intubation, and at the time of extubation in the SGB combined with GA group were lower than those in the GA alone group (P < 0.05), and repeated measures ANOVA showed that the between-group, time, and interaction effects were all significant (P < 0.001). Under GA, invasive operations involving tracheal intubation can stimulate the organism, leading to hemodynamic fluctuations, mainly manifested by an increase in blood pressure and heart rate, affecting myocardial blood supply and oxygenation, triggering cardiac arrhythmias, increasing sympathetic excitability, and inhibiting the secretion of acetylcholine. This chain of events leads to the expression of a large number of inflammatory factors caused by the trauma of the surgery which then enter the brain tissue, generating cytotoxic reactions, damaging the hippocampus, basal ganglia, and other areas, and impairing the cognitive function of patients[9,10]. The ability of SGB to modulate the sympathetic nervous system, which in turn affects the immune and endocrine systems. SGB can reduce the release of stress hormones such as cortisol and adrenaline, which are known to increase inflammation and suppress immune function. By blocking the sympathetic nerves, SGB can decrease the production of pro-inflammatory cytokines like IL-6 and TNF-α, which are involved in the inflammatory response and can contribute to postoperative complications. Additionally, SGB may enhance the activity of the parasympathetic nervous system, which is associated with anti-inflammatory and immunomodulatory effects, promoting a more balanced immune response. In addition, conducting anesthesia under ultrasound guidance can determine accurate positioning, ensure an anesthetic effect while reducing the dosage of drugs, and prevent complications.

The results of our study showed that the levels of MDA and NO in the SGB combined with GA group were significantly lower than those in the GA alone group (P < 0.05), the levels of SOD were significantly higher than those in the GA alone group (P < 0.05), and the levels of Aβ-42, IL-6, and tau-181 proteins were significantly lower than those in the GA alone group (P < 0.05) in the postoperative period of 24 hours, a result that supports the hypotheses of this study. Surgical trauma and GA drugs activate the sympathetic-adrenomedullary system and the hypothalamic-pituitary-adrenocortical axis, triggering systemic inflammatory responses and oxidative stress. Oxidative stress is mainly characterized by an imbalance between oxidation and antioxidants, which can increase the release of reactive oxygen species and other harmful substances, causing an inflammatory response in the body. Surgical procedures can change the levels of oxidative stress indicators, which decrease the levels of antioxidant factors and increase the levels of oxidative factors[11]. MDA is metabolized by lipid peroxidation, which can damage the structure of biological membranes and increase cell permeability. NO is generated by NO synthase, which catalyzes the release of levulinic acid. Levulinic acid can combine with hydroxyl radicals to generate more toxic free radicals and exacerbate tissue damage. SOD eliminates free radicals, which have an antagonistic effect on cellular damage caused by oxygen radicals, and can repair damaged cells and reduce cellular damage[12,13]. The researchers found that the SGB combined with GA group had lower levels of MDA and NO and higher levels of SOD after surgery, suggesting that SGB combined with GA can block the sympathetic nerve in the neck. Local anesthetic drugs can produce nerve impulses through in this location, reduce the stimulation of the body caused by surgical treatment, tracheal intubation, and other procedures, inhibit the expression of highly active molecules, stimulate the secretion of antioxidant substances, and reduce oxidative stress damage. Moreover, more significant procedures such as surgery and anesthesia can trigger a stress response, prompting the release of inflammatory factors and altering neurotransmitter levels, which in turn impair cognitive function. IL-6 crosses the compromised blood-brain barrier and activates microglia within the central nervous system to induce neuroinflammation and is primarily used in the assessment of inflammatory responses, which can be triggered or exacerbated by elevated levels of IL-6. Neuroinflammation and oxidative stress contribute to each other and collectively can cause neuronal damage, synaptic dysfunction. The production of Aβ-42 and hyperphosphorylation of tau proteins, which are catabolized by the β-amyloid precursor protease and can be used to assess postoperative cognitive function. Tau proteins, which are mainly distributed in the nervous system, stabilize the microtubule structure, and can also be used in the assessment of cognitive function[14,15]. In the present study, the levels of Aβ-42, IL-6, and tau-181 proteins in the SGB combined with GA group were lower than those in the GA alone group at 24 hours postoperatively, suggesting that SGB combined with GA can reduce the inflammatory response and neuroinflammation triggered by surgery and anesthesia, and thus reduce cognitive function impairment.

Our assessment of cognitive function showed that although both groups demonstrated a decline in MMSE and MoCA scores at 24 hours postoperatively, the decline was significantly smaller in the SGB combined with GA group than that in the GA alone group. The between-group difference in the MoCA scores was 0.98 points (95%CI: 0.55-1.41). Although this difference did not reach what is commonly considered the minimally clinically important difference (where a change in MoCA of ≥ 2 points is usually considered clinically significant), it suggests that SGB has a statistically significant tendency to attenuate cognitive decline in the early postoperative period. Combined with the significant improvements in serum nerve damage markers (Aβ-42, tau-181) and inflammatory factors (IL-6), this suggests that SGB may have a protective effect on cognitive function by reducing neuroinflammation and neuronal damage. Our results are similar to those of previous studies reporting that SGB improves cognitive function or pain-accompanying cognitive deficits after stroke. However, our study may be the first to confirm the potential protective effect of SGB on cognitive function in the early postoperative period in a specific scenario of gastrointestinal surgery. Longer follow-up is needed to assess the long-term effects and clinical significance.

In the analysis of gastrointestinal function, our results showed that the level of gastric motilin was higher in the SGB combined with GA group than that in the GA alone group at 24 hours postoperatively (P < 0.05), and the level of vasoactive peptide was lower than that in the GA alone group (P < 0.05). The sympathetic and parasympathetic nerves jointly regulate the function of the gastrointestinal tract. Sympathetic excitation can stimulate the release of catecholamines, leading to vasoconstriction of the gastrointestinal tract, inhibition of muscle activity and mucus secretion, and destruction of the digestive tract barrier, impacting the function of the gastrointestinal tract. Gastrin can regulate gastrointestinal motility, and has a regulatory effect on gastrointestinal digestion, absorption, and secretion; it can maintain the normal structure of the gastrointestinal tract, regulate peristalsis, regulate appetite, stimulate gastric juice secretion, and protect the gastric mucosal tissues. A decrease in the gastrin level suggests impairment of gastrointestinal tract function[16]. Vasoactive peptide is an intestinal hormone that can diastole intestinal smooth muscle and relax the lower esophageal sphincter and internal anal sphincter, and an increase in its level suggests gastrointestinal dysfunction. Our results are consistent with Ruan et al’s study[16]; the SGB combined with GA group had higher levels of gastric motilin and lower levels of vasoactive peptide after surgery, indicating that SGB anesthesia can reduce postoperative gastrointestinal dysfunction. SGB anesthesia inhibits sympathetic excitability. However, parasympathetic excitability can be beneficial as it can promote gastrointestinal activity and stimulate the secretion of digestive juices. This reduces the effect of surgery on the gastrointestinal hormone levels and relieves postoperative gastrointestinal dysfunction.

In addition, long-term clinical practice has shown that SGB may have a protective role through the following mechanisms: (1) Inhibiting sympathetic over-activation and reducing catecholamine release, thus reducing systemic inflammatory response and oxidative stress levels; (2) Regulating immune function and inhibiting the production and release of pro-inflammatory factors, such as IL-6 and TNF-α; (3) Improving cerebral blood flow and oxygen supply to alleviate ischemia-reperfusion injury; and (4) Directly or indirectly inhibit neuroinflammatory pathways such as NLRP3 inflammatory vesicle activation, reduce central nerve inflammation and neuronal damage, and subsequently reduce the expression or release of Aβ-42 and tau-181 proteins[17,18]. Moreover, the application of SGB in gastrointestinal surgery has unique advantages: (1) The operative site is far from the surgical field and abdominal blood vessels and will not affect the mechanics of the surgery; (2) Ultrasound-guided operation is safe; no SGB-related complications occurred in this study, and other studies have shown that the rate of serious complications is extremely low; and (3) A unilateral block can exert a significant anti-stress and neuromodulatory effect, thereby avoiding the risk and hemodynamic effects of bilateral blocks or thoracic epidural anesthesia which can cause hypotension. However, SGB mainly acts on the head, neck, upper limbs, and part of the thoracic cavity, and its modulation of the function of abdominal organs is mainly a systemic effect achieved by the central inhibition of sympathetic nerves and/or enhancement of vagal tone, rather than direct local innervation blockade. Therefore, SGB is more suitable as an adjunct to GA for hemodynamic stabilization, stress reduction, and potential neuroprotection than as a substitute for postoperative analgesia.

This study had certain limitations, such as a single sample source (only laparoscopic surgery patients were included), a short observation time (24 hours postoperatively), and the lack of analysis of other important inflammatory factors that could be impacted by anesthesia. Future studies should consider including patients undergoing open abdominal and other types of surgeries, prolonging the observation time, and detecting other inflammatory factors and markers of neurological injury to more comprehensively assess the protective effects of SGB in gastrointestinal surgery.

CONCLUSION

In conclusion, our study demonstrates that the integration of SGB with GA in patients undergoing gastrointestinal surgery is associated with significant benefits. This combined approach effectively maintains perioperative hemodynamic stability, reduces oxidative stress and neuroinflammatory injury, mitigates postoperative cognitive decline, and enhances gastrointestinal recovery function. These findings suggest that SGB may serve as a valuable adjunct to GA, potentially leading to improved patient outcomes and a reduced risk of postoperative complications. Despite the promising results, our study is not without limitations, including a relatively small sample size and a non-randomized design, which may impact the generalizability of our findings. Future research with larger, randomized samples and a broader range of surgical procedures is needed to further substantiate these benefits and explore the full potential of SGB in surgical care.