Introduction: Chronic internal carotid artery occlusion (CICAO) is a common cause of stroke and ischemia recurrence. An increasing number of reports have highlighted the potential of hybrid surgery for treating CICAO. There are few studies, specifically nonrandomized controlled trials, on the safety and effectiveness of hybrid surgery for the treatment of CICAO, so in this study, we hypothesized that hybrid surgery would be safe, have an acceptable complication rate and a high success rate. Methods: MEDLINE, Embase, Cochrane Library, and Web of Science databases were searched for relevant studies published up to January 30, 2023. The primary endpoint was recanalization rates of occluded vessels, and the secondary endpoint was perioperative death and procedure-related complications. Subgroup analysis focused on the recanalization rates of endovascular intervention (EI) and hybrid surgery, as well as the rates of recanalization below the clinoid segment and at the clinoid segment and beyond. The follow-up visit was conducted at least 3 months after surgery, and stenosis or occlusion recurrence was confirmed by review of CTA or DSA scan. Results: The databases were searched and 1,709 records were identified, of which 16 articles were used in the meta-analysis, and 464 CICAO patients with complete data who underwent hybrid surgery were enrolled. Hybrid surgery was associated with higher success rates (RD = 0.87, 95% CI [0.84–0.91], p < 0.00001) than EI (OR = 4.71, 95% CI [2.32–9.56], p < 0.0001). The procedural success rate in the below-clinoid segment group was significantly higher than that in the clinoid segment and beyond group (OR = 13.76, 95% CI [5.31–35.66], p < 0.00001). The total periprocedural complication rate was low (RD = 0.11, 95% CI [0.07–0.15], p < 0.00001 and RD = 0.04, 95% CI [0.00–0.07], p = 0.03). Target vessel restenosis or reocclusion occurred in 35 patients (8%) during the follow-up period (RD = 0.08, 95% CI [0.04–0.12], p < 0.0001). Conclusion: Hybrid surgery is the combination of the advantages of open surgery and EI, has a high success rate and a low risk of recurrence of stenosis and occlusion in the long term. Randomized controlled trials on hybrid surgery for internal carotid artery occlusion are necessary.

As the clinical detection rate for chronic internal carotid artery occlusion (CICAO) has increased, its close relationship with stroke has been scrutinized. CICAO is defined as an occlusion lasting more than 4 weeks [1], and its clinical expression varies, including asymptomatic, transient ischemic attack (TIA), and acute ischemic stroke (AIS). The annual risk of cerebrovascular events, including stroke, due to symptomatic CICAO is estimated at 10–18%, which is higher than that due to asymptomatic CICAO. Patients with CICAO usually have hemodynamic disorders, which increase the risk of stroke, and the mortality rate may be as high as 16–55% [2]. The efficacy of intravenous thrombolytic therapy (e.g., recombinant tissue-type plasminogen activator [rtPA]) for the treatment of AIS has been proven but not in those with CICAO; however, such therapy may even lead to severe intracranial hemorrhage or death. Moreover, evidence has shown that thrombolytic therapy effectively improves patients’ abilities to perform activities of daily living, but it also increases the risks of death and intracranial bleeding [3]. Endovascular treatment (EVT) based on mechanical thrombectomy has improved the prognosis of AIS secondary to CICAO. Although the rates of excellent outcome and secondary bleeding in EVT were both significantly higher than those in thrombolytic therapy, there was no change in mortality rates [4]. However, interventional treatment of carotid artery occlusion still has limitations. EVT may not be able to reach the distal end of the occlusion, or puncture may lead to the formation of iatrogenic dissection, resulting in thrombosis, new vessel occlusion, or new ischemic events, which may lead to massive hemorrhage after penetrating through the full thickness and provide opportunities for recanalization, thereby increasing the challenge and difficulty. Hybrid surgery is composed of carotid endarterectomy (CEA) and balloon thrombectomy or carotid artery stenting, which can remove the thrombus in the carotid artery after resolving carotid artery stenosis or directly reach the distal end of the occlusion from the true lumen, thus improving the vascular recanalization rate of CICAO. There are currently no randomized controlled trial studies on the treatment of carotid occlusion or systematic reviews and meta-analyses on hybrid surgery for CICAO. Thus, an updated systematic review and meta-analysis are necessary to provide a reference for the choice of CICAO treatment.

This study was conducted in accordance with the updated Preferred Reporting Items for Systematic Reviews and Meta-Analyses (online suppl. PRISMA 2020; for all online suppl. material, see https://doi.org/10.1159/000535373) reporting guidelines for meta-analyses [5] and was registered in PROSPERO (CRD42023428292).

Inclusion and Exclusion Criteria

Patients with complete occlusion of one side of the internal carotid artery confirmed by CTA or DSA, neurological deficits, or imaging findings related to the responsible vessel, which is symptomatic CICAO, were the subjects in the study population in these studies. Both experimental and observational studies were included. Symptoms do not improve, or symptoms recur after standard antiplatelet and statin drug therapy. All patients in these studies underwent hybrid surgery, which combined both CEA and balloon thrombectomy or carotid artery stenting. Perioperative outcomes, postoperative complications, and completed follow-up data were recorded. Case reports, case series, systematic reviews, meta-analyses, literature reviews, and editorial comments were excluded.

Data Sources and Search Strategy

The following databases were searched for relevant studies published up to January 30, 2023: MEDLINE (via PubMed), Embase, Cochrane Library, and Web of Science databases. No restrictions were placed on the language or country of publication. Subject words and free words, including “carotid artery occlusion,” “artery occlusion,” “carotid, or carotid arterial constriction,” “hybrid treatment,” “hybrid surgery,” or “hybrid operation,” were combined during study retrieval. The complete search used for Embase was as follows: (“carotid artery occlusion”/exp OR “carotid artery occlusion” OR “artery occlusion, carotid”:ab,ti OR “carotid arterial constriction”:ab,ti OR “carotid arterial occlusion”:ab,ti OR “carotid arterial occlusive disease”:ab,ti OR “carotid arteries occlusion”:ab,ti OR “carotid artery constriction”:ab,ti OR “carotid artery obstruction”:ab,ti OR “carotid artery occlusive disease”:ab,ti OR “carotid obliteration”:ab,ti OR “carotid occlusion”:ab,ti OR “occluded carotid arteries”:ab,ti OR “occluded carotid artery”:ab,ti OR “occlusion of the carotid”:ab,ti OR “occlusion of the carotid artery”:ab,ti OR “occlusive carotid disease”:ab,ti OR “occlusive disease of the carotid”:ab,ti OR “carotid artery occlusion”:ab,ti AND “hybrid treatment”:ab,ti OR “hybrid surgery”:ab,ti OR “hybrid operation”:ab,ti).

Study Selection and Data Extraction

The results were screened for suitability by two independent reviewers (Tan and Wang), including the title, abstract, and full-text report, with any disputes resolved by a third reviewer (He). The data were collected in a predesigned spreadsheet (Microsoft Excel), two review authors extracted data from eligible studies, and any disagreement was resolved by consensus or consultation with a third author (He). Statistical analyses and graphing were performed using Review Manager software (version 5.4.1). Publication bias was assessed using a funnel plot and Egger’s test. Funnel plots and sensitivity analysis were drawn by Stata/SE version 16.0 (Stata Corp, College Station, TX, USA).

Statistical Analysis

The extracted study characteristics included authors, publication year, number of patients included, female-to-male sex ratio, mean age of patients, other sample information, and intervention details. We also investigated the procedural difficulty of the hybrid surgery using subgroup analyses. To reduce heterogeneity, according to the occlusion site, the internal carotid artery was divided into below the clinoid segment (including the cervical segment, petrous segment, rupture foramen segment, and cavernous sinus segment) and above the clinoid segment of the internal carotid (clinoid segment, ophthalmic segment, and communicating segment). Intraoperative and postoperative complications were counted, mainly including hyperperfusion syndrome (including headache, focal neurological deficit, cerebral hemorrhage, and subarachnoid hemorrhage), secondary epilepsy, inguinal hematoma, cervical hemorrhage or incisional infection, laryngeal nerve injury, iatrogenic arterial dissection, carotid-cavernous fistula, or new ischemic stroke. The number of deaths within 30 days after surgery was recorded, and the reocclusion or restenosis of the target vessel was followed up for at least 3 months (determined by re-examination of CTA or DSA). The outcome of dichotomous variables was analyzed by calculating the OR value, and the success or occurrence outcome of the single-arm study was analyzed using the RD (risk difference) value, including their I2 values and 95% CI (Fig. 1a, b).

Fig. 1.

a Funnel plot for publication bias. b Egger’s test showed p = 0.074, indicating no evidence of significant publication bias.

Fig. 1.

a Funnel plot for publication bias. b Egger’s test showed p = 0.074, indicating no evidence of significant publication bias.

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Study Selection

We retrieved 1,709 publications in the above databases: 65 from Embase, 779 from PubMed, and 865 from Web of Science. Duplicate articles, title abstracts, and full texts were screened, and irrelevant articles, case reports, and letters were excluded. One study with carotid stent restenosis hybrid surgery recanalization was excluded, and 16 eligible studies were finally included [6‒21] (Fig. 2). All included studies were written in English, and some studies were excluded due to incomplete outcome data [22]. The funnel plot was symmetrical, suggesting a low risk of publication bias. In addition, p values for Egger’s tests were >0.05 (p = 0.074), also suggesting no significant publication bias in our meta-analysis (Fig. 1a, b). The sensitivity analysis showed that the study results of 16 articles had similar distributions on both sides, good credibility and stability, as shown in Figure 3.

Fig. 2.

Flowchart of the study selection process.

Fig. 2.

Flowchart of the study selection process.

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Fig. 3.

Sensitivity analysis.

Fig. 3.

Sensitivity analysis.

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Study Characteristics

A total of 681 CICAO patients were included and underwent surgery in 16 studies, of which 462 patients underwent hybrid surgery, 4 studies also compared endovascular intervention, and 394 patients who underwent hybrid surgery experienced successful recanalization of the occluded carotid artery during the operation. At the same time, carotid artery occlusion in the included studies was more prevalent in males than in females (with a mean of 81.3%). The average age of the included patients ranged from 55 to 67 years old, and in one study, the average age of the male and female patients was calculated separately [9], and in another study, the specific sex ratio was not calculated [18] (Table 1).

Table 1.

Characteristics of the included studies

Participants, nMaleAgeTreatment
Fan [9] (2019) 23 17 (73.9%) M: 64.23/F: 61.33 Hybrid treatment 
Fan et al. [17] (2021) 56 35 (62.5%) 66.00 (7.90) Hybrid treatment 
Gong [14] (2020) 124 85 (68.5%) 61 (8) Hybrid treatment/EI 
Jiao [6] (2013) 65 59 (90.7%) 60.7 (8.9) Hybrid treatment 
Li et al. [10] (2019) 32 25 (78.1%) 65.8 (8) Hybrid treatment/EI 
Liu et al. [8] (2018) 21 19 (90.4%) 56 Hybrid treatment 
Ma [11] (2019) 6 (75%) 67 Hybrid treatment 
Peng et al. [20] (2022) 15 13 (86.6%) 63.7 (6.7) Hybrid treatment 
Sun et al. [12] (2019) 21 16 (76.1%) 64 (8) Hybrid treatment 
Sun et al. [21] (2022) 79 71 (89.8%) 63.34 (6.88) Hybrid treatment/EI 
Wang [7] (2014) 12 10 (83.3%) 67 (6.45) Hybrid treatment 
Wang et al. [18] (2021) 16 NO 63.85 (7.9)/TO 67 (6.28) Hybrid treatment 
Yan et al. [15] (2020) 37 33 (89.1%) 62.1 (6.4) Hybrid treatment 
Yang et al. [16] (2020) 55 45 (81.8%) 59.3 (8.8) Hybrid treatment 
Zhang [19] (2021) 66 53 (80.3%) 60.4 (8.8) Hybrid treatment 
Zhao et al. [13] (2019) 51 48 (94.1%) 55.4 (8.8) Hybrid treatment/EI 
Participants, nMaleAgeTreatment
Fan [9] (2019) 23 17 (73.9%) M: 64.23/F: 61.33 Hybrid treatment 
Fan et al. [17] (2021) 56 35 (62.5%) 66.00 (7.90) Hybrid treatment 
Gong [14] (2020) 124 85 (68.5%) 61 (8) Hybrid treatment/EI 
Jiao [6] (2013) 65 59 (90.7%) 60.7 (8.9) Hybrid treatment 
Li et al. [10] (2019) 32 25 (78.1%) 65.8 (8) Hybrid treatment/EI 
Liu et al. [8] (2018) 21 19 (90.4%) 56 Hybrid treatment 
Ma [11] (2019) 6 (75%) 67 Hybrid treatment 
Peng et al. [20] (2022) 15 13 (86.6%) 63.7 (6.7) Hybrid treatment 
Sun et al. [12] (2019) 21 16 (76.1%) 64 (8) Hybrid treatment 
Sun et al. [21] (2022) 79 71 (89.8%) 63.34 (6.88) Hybrid treatment/EI 
Wang [7] (2014) 12 10 (83.3%) 67 (6.45) Hybrid treatment 
Wang et al. [18] (2021) 16 NO 63.85 (7.9)/TO 67 (6.28) Hybrid treatment 
Yan et al. [15] (2020) 37 33 (89.1%) 62.1 (6.4) Hybrid treatment 
Yang et al. [16] (2020) 55 45 (81.8%) 59.3 (8.8) Hybrid treatment 
Zhang [19] (2021) 66 53 (80.3%) 60.4 (8.8) Hybrid treatment 
Zhao et al. [13] (2019) 51 48 (94.1%) 55.4 (8.8) Hybrid treatment/EI 

Date are n (%), mean/mean (SD).

EI, endovascular intervention; NO, near-total occlusion; TO, total occlusion.

Quantitative Meta-Analysis

The recanalization rate of hybrid surgery was inconsistently reported in various studies; the highest recanalization rate was 100% and was reported by Ma [11] (all 8 patients were successfully recanalized); and the lowest was 71.4% and reported by Liu [8] (21 patients included, 15 cases of recanalization). Overall, the success rate of recanalization of an occluded internal carotid artery during hybrid surgery was relatively high (RD 0.87, 95% CI [0.84–0.91], I2 = 17%, p < 0.00001). In the subgroup analysis, four studies were included. Compared with 111 of 157 patients who experienced successful recanalization during a simple endovascular intervention therapy, 116 of 129 patients experienced successful recanalization of the occluded internal carotid artery during hybrid surgery. The recanalization rate of hybrid surgery was higher, showing that the effectiveness of hybrid surgery was better than that of simple endovascular intervention (OR 4.71, 95% CI [2.32–9.56], I2 = 0%, p < 0.0001). In addition, four studies compared the difference in the recanalization rate of the occluded segment below the clinoid segment of the internal carotid artery and the clinoid segment of the internal carotid artery and beyond. The subclinoid group included 147 patients, of whom 135 experienced successful recanalization. In 55 patients, the occluded segment was located at the clinoid segment and above the clinoid segment, of whom only 29 patients experienced successful recanalization of the occluded carotid artery, and the success rate was significantly lower than that of the subclinoid segment group (OR 13.76, 95% CI [5.31–35.66], I2 = 0%, p < 0.00001). This shows that for the occluded segment in the lower carotid artery segment, the probability of recanalization by hybrid surgery is higher as it may be a more aggressive treatment (Fig. 4).

Fig. 4.

Success rate of hybrid surgery for recanalization of the occluded internal carotid artery, the success rate of hybrid surgery and the comparison with the EI group, and the comparison of the success rate of different occlusion sites in subgroup analysis. EI, endovascular intervention.

Fig. 4.

Success rate of hybrid surgery for recanalization of the occluded internal carotid artery, the success rate of hybrid surgery and the comparison with the EI group, and the comparison of the success rate of different occlusion sites in subgroup analysis. EI, endovascular intervention.

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All 16 included studies reported perioperative complications and all-cause mortality. A total of 56 cases of perioperative complications were reported for 462 patients, including postoperative cerebral hyperperfusion (including headache, delirium, hyperexcitability, cerebral hemorrhage, and subarachnoid hemorrhage; 19 patients; 33.9%), cervical hemorrhage (7 patients; 12.5%; 1 patient had a compressed trachea and underwent open surgery for decompression again), laryngeal nerve injury causing coughing and hoarseness (6 patients; 10.7%), cerebral hemorrhage (5 patients; 8.9%), new cerebral infarction after surgery (4 patients; 7.1%), carotid-cavernous sinus fistula caused by surgery (4 patients; 7.1%), cardiovascular events (3 patients; 5.3%), surgical incision infection (2; 3.5%), wound swelling (non-hematoma; 2 patients; 3.5%), hematoma at the groin puncture site (1 patient; 1.7%), and iatrogenic carotid artery dissection (1 patient; 1.7%). One (1.7%) case of treatment-resistant hypertension and 1 (1.7%) case of postoperative secondary epilepsy were observed. A total of 6 patients died within 30 days after surgery, including 2 (33.3%) deaths due to new intracerebral hemorrhage after surgery and 2 (33.3%) deaths due to perioperative cardiovascular events or acute myocardial infarction. One patient (16.6%) died of operation failure, and 1 patient (16.6%) died of underlying heart disease. The complication rate in the perioperative period (RD 0.11, 95% CI [0.07–0.15], I2 = 46%, p < 0.00001) and the mortality rate within 30 days after the operation (RD 0.04, 95% CI [0.00–0.07], I2 = 0%, p = 0.03 < 0.05) were both low (Fig. 5). Thirteen studies reported the time and method of surgical follow-up for 246 patients. The shortest follow-up time was 4 months [16] after surgery, and the longest follow-up time was 49 months [21] after surgery. A total of 19 (7.7%) patients who were followed up reported recurrences of stenosis and 17 (6.9%) cases of reocclusion. The restenosis or occlusion rate of the responsible vessel during the follow-up period was low overall (RD 0.08, 95% CI [0.04–0.12], I2 = 42%, p < 0.0001) (Fig. 6).

Fig. 5.

Perioperative complications and deaths within 30 days after surgery.

Fig. 5.

Perioperative complications and deaths within 30 days after surgery.

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Fig. 6.

Follow-up of target vessel reocclusion or restenosis, with a follow-up time of at least 3 months (determined by CTA or DSA review).

Fig. 6.

Follow-up of target vessel reocclusion or restenosis, with a follow-up time of at least 3 months (determined by CTA or DSA review).

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The long-term stroke rate in individuals with CICAO is 8 times higher than that of the normal population. In particular, patients who have experienced TIA or minor stroke are at greater risk of stroke recurrence. Current treatment for CICAO mostly includes drug-based secondary prevention of stroke. Our study shows that hybrid surgery has a higher success rate for recanalizing occluded internal carotid arteries and is more likely to be successful than simple endovascular interventional surgery in recanalizing occluded vessels. The reason may be that hybrid surgery makes up for the difference between CEA and simple interventional surgery. CEA surgery is disadvantageous in that it is only suitable for occlusion of a short segment of the lower end of the carotid artery. Because of long segments occluded with several thrombi in the intracranial vessels, the guidewire may not be able to be advanced to the intracranial segment through the old thrombus, which reduces the likelihood of a successful surgery; however, hybrid surgery combined with carotid artery incision (CEA) has advantages in opening long-segment-occluded blood vessels. Similar to the results of previous studies, we found that the success rate of canalization for occluded segments at and below the clinoid segment of the internal carotid artery was significantly higher than that for those above the clinoid segment, and the latter had higher complication and perioperative mortality rates. Generally, the risk of serious complications during the perioperative period of composite surgery is low. The top three complications are brain tissue hyperperfusion syndrome, neck incision hematoma, and hoarseness caused by laryngeal nerve damage. These complications are controllable or can be remedied in time. Strict postoperative blood pressure control can reduce the occurrence of overperfusion. By improving the surgeon’s skills and proficiency, performing maneuvers carefully during the operation can avoid causing a hematoma and nerve damage around the incision to some extent. Injuries, some hematomas, and most nerve injuries usually resolve spontaneously without further surgical intervention. The 30-day mortality rate after composite surgery is low, and the main cause of death is underlying disease or heart disease. The secondary cause is postoperative cerebral hemorrhage or surgical failure. During long-term postoperative follow-up, it was found that the reocclusion rate of blood vessels after hybrid surgery was generally low, below 10%, confirming the effectiveness and safety of hybrid surgery for treating CICAO. Our research results can provide a theoretical basis for the formulation of surgical strategies for patients with chronic carotid artery occlusion. When there is difficulty in recanalizing the occluded internal carotid artery during simple interventional surgery or CEA surgery, hybrid surgery may be a better choice. Surgery may compensate for the shortcomings of both. Previous studies on CICAO composite surgery were limited by small sample sizes, and the conclusions reached were inconsistent. There are currently few systematic reviews and meta-analyses on CICAO composite surgery. Our study fills the gap in this field. In addition, our study found that the lower morbidity and mortality rates after hybrid surgery may increase the confidence of doctors who are preparing to complete internal carotid artery occlusion recanalization surgery, providing a positive outlook for hybrid surgical treatment of chronic carotid artery occlusion.

At present, it is recommended to control stroke risk factors for asymptomatic CICAO, such as hypertension, diabetes, hyperlipidemia, smoking, etc., while considering the high stroke recurrence rate in CICAO; thus, secondary prevention of stroke based on antiplatelet aggregation and statin therapy is particularly important. However, even with strict and intensive medical therapy, the annual stroke recurrence rate of CICAO is still as high as 6–20%. Revascularization techniques are mainly intracranial and extracranial vascular bypass surgery (such as superficial temporal artery-middle cerebral artery bypass surgery). Studies have shown that it can reduce the incidences of postoperative stroke recurrence and mortality, but there are not enough RCT studies to prove that revascularization therapy is better than medication alone [23]. It is generally believed that bypass surgery is recommended to reconstruct cerebral blood flow in patients with hemodynamic disturbance or recurrent stroke for whom drug therapy is ineffective, but the effect is uncertain. CEA is suitable for cases where the occlusion position is low and there is no long-segment thrombus formation in the distal end; however, its scope of application is limited. Our included studies also show that CEA combined with balloon thrombectomy may be more effective. Vascular recanalization therapy based on endovascular interventional surgery can recanalize intracranial occluded vessels, which provides the possibility for recanalization of long-segment carotid artery occlusions and is considered beneficial for patients with CICAO and hemodynamic disorders. Carotid artery color Doppler ultrasound, CTA, DSA, and MR plaque analysis should be comprehensively assessed before surgery, and suitable cases should be screened before surgery. Some studies have shown that nonlimited vascular occlusion of the clinoid segment and beyond is not recommended for vascular recanalization because of the low success rate, risk of complications, and high long-term reocclusion rate, while cases of localized vascular occlusion above the clinoid segment and long-segment occlusion below the clinoid segment have a higher surgical success rate, and recanalization can be attempted. ICARO-3, a prospective cohort analysis of 37 centers in 7 countries, showed that endovascular therapy for acute stroke secondary to carotid occlusion did not produce better functional outcomes than intravenous thrombolysis and may lead to a higher rate of intracranial hemorrhage, but a subgroup analysis excluding patients who were bridging endovascular therapy after intravenous thrombolysis showed a potential benefit of endovascular therapy, confirming the value of endovascular therapy [24].

An increasing number of large centers have established hybrid operating rooms, and advances in technology may improve the success rate of the recanalization of carotid artery occlusion. For cases where the occluded segment is located in the lower part of the carotid artery, such as the petrous segment and the lower segment of the petrous bone, CEA is the first choice. Hybrid surgery can be combined with balloon mechanical thrombectomy, which compensates for failure to reach the distal end of the carotid artery or deal with a long-segment thrombus in simple surgery. Our study also confirmed that the success rate of surgery is higher for patients with low occlusion segments. Although simple endovascular intervention is less traumatic, it has some limitations, such as being a blind operation, the guide wire or catheter cannot enter the true lumen of the vessel, and the increased risk of iatrogenic carotid artery dissection caused by a puncture. The operation combined with CEA allows complete removal of atherosclerotic plaque, and the backflow of blood flushes the thrombus, thus reducing the risk of distal embolism. Intraluminal puncture of the artery under direct vision can improve the success rate of puncture and make it easier to reach the distal end of the occluded vessel, which is key to achieving vascular recanalization during surgery. For long-segment occlusions from the initial segment to above the petrosal segment, hybrid surgery or simple endovascular intervention can be considered. If the vessel collapses or stenosis occurs after recanalization, it can be combined with carotid artery stent implantation and angioplasty. Hybrid surgery for perioperative complications is similar to simple CEA or endovascular interventional therapy. The main perioperative complication in our study was cerebral hyperperfusion after recanalization, which led to symptoms such as excitement and headache in patients. Severe cases are life threatening due to cerebral hemorrhage, so postoperative blood pressure control is particularly important. The common complication of CEA is cervical hematoma, which is related to the long-term use of antiplatelet drugs in patients with cerebral infarction and difficult hemostasis during the operation. It is necessary to operate carefully under a microscope and complete hemostasis to avoid damaging the laryngeal nerve and thereby causing the patient to choke and experience hoarseness. Puncture complications mainly include carotid-cavernous fistula caused by carotid artery puncture and bleeding at the groin puncture site. This complication is related to the technical experience of the surgeon.

Notably, the included studies have some limitations. First, almost all the studies that finally met the inclusion criteria were published by Chinese scholars. The reason may be due to China’s large population and the incidence of ischemic stroke. Chinese scholars are more active in exploring the application of hybrid surgery for the treatment of CICAO. Second, the study included a specific population, so the application of its findings to other populations is limited. This study mainly included patients with symptomatic internal carotid artery occlusion, such as patients with internal carotid artery system TIA or cerebral infarction, and lacked guiding significance for asymptomatic patients. There was a certain degree of heterogeneity in the included studies. Some studies included patients who were refractory to antiplatelet drug treatment, while others did not provide detailed explanations for this, such as the study by Jiao and Wang 2014. Jiao’s study only described perioperative mortality and did not describe the occurrence of complications in detail. Zhang 2014’s study included too few medical records and may be an early exploratory study. There are also gaps in the included studies in terms of follow-up time. Jiao and Wang 2014 and Li 2019 did not describe whether there was reocclusion of blood vessels after opening during follow-up. Only 4 studies were comparative in that hybrid surgery was compared with simple interventional surgery. In addition, the limitation of our study is that all the included studies were retrospective single-arm studies, and retrospective study data collection may be biased. Second, the sample size of the included studies was small. Finally, more RCT studies may be able to confirm the effectiveness and safety of hybrid surgery.

Hybrid surgery for CICAO is effective and possibly safe, and relevant randomized controlled trials are necessary.

An ethics statement is not applicable because this study is based exclusively on published literature.

The authors have no conflicts of interest to declare.

No funding was obtained.

Guanping Tan and Zhaohui He conceived and designed the study. Guanping Tan and Jing Wang performed search of the data. Wenli Xing conducted the systematic review and meta-analysis. Guanping Tan, Jing Wang and Zhaohui He drafted and critically revised the manuscript.

Additional Information

Guanping Tan and Jing Wang have contributed equally to this work and share first authorship.

All data generated or analyzed during this study are included in this article and its online supplementary files. Further inquiries can be directed to the corresponding author.

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