Discontinuity of marginal artery at splenic flexure and rectosigmoid junction: A systematic review and meta-analysis.

AIM: The aim of this study was to provide comprehensive evidence-based assessment of the discontinuity of the marginal artery at the splenic flexure (SF) and the rectosigmoid junction (RSJ). METHOD: A systematic review was conducted of literature published to 26 December 2022 in the electronic databases PubMed, SCOPUS and Web of Science to identify studies eligible for inclusion. Data were extracted and pooled into a meta-analysis using the Metafor package in R. The primary outcomes were the pooled PPEs of the marginal artery at the SF and the RSJ. The secondary outcome was the size of vascular anastomoses. RESULTS: A total of 21 studies (n = 2,864 patients) were included. The marginal artery was present at the splenic flexure in 82% (95% CI: 62-95) of patients. Approximately 81% (95% CI: 63-94%) of patients had a large macroscopic anastomosis, while the remainder (19%) had small bridging ramifications forming the vessel. The marginal artery was present at the RSJ in 82% (95% CI: 70-91%) of patients. CONCLUSION: The marginal artery may be absent at the SF and the RSJ in up to 18% of individuals, which may confer a higher risk of ischaemic colitis. As a result of high interstudy heterogeneity noted in our analysis, further well-powered studies to clarify the prevalence of the marginal artery at the SF and the RSJ, as well as its relationship with other complementary colonic collaterals (intermediate and central mesenteric), are warranted.

Cell-Free DNA, Neutrophil extracellular traps (NETs), and Endothelial Injury in Coronavirus Disease 2019- (COVID-19-) Associated Acute Kidney Injury.

Introduction: Neutrophil extracellular traps (NETs) release (i.e., NETosis) has been recently implicated in the pathomechanism underlying severe end-organ damage in Coronavirus Disease 2019 (COVID-19) and could present a novel therapeutic target. We aimed to determine whether circulating levels of cell-free DNA (cfDNA), a surrogate for NETosis, may be associated with the development of acute kidney injury (AKI), a major contributor to poor outcomes and mortality in COVID-19. Methods: Blood samples were collected prospectively from adult patients infected with SARS-CoV-2 presenting to the emergency department (ED). Circulating levels of cfDNA were quantified from patients' serum. Further assessment of correlations between cfDNA levels and markers of AKI (i.e., serum creatinine (SCr), cystatin C, neutrophil gelatinase-associated lipocalin (NGAL)), biomarkers of thrombotic microangiopathy and of inflammation in patients' serum was performed. Results: Fifty-one COVID-19 patients were enrolled. cfDNA levels were found to be significantly higher in those who developed severe AKI (p < 0.001) and those needing renal replacement therapy (p = 0.020). cfDNA positively correlated with ED SCr, NGAL, cystatin C, neutrophil count, neutrophil-to-lymphocyte ratio, C3a, C5a, Scb5-9, IL-6, IL-8, IL-10, TNF-α, LDH, CRP, ferritin, and fibrinogen and negatively correlated with ADAMTS13/von-Willebrand factor ratio and lymphocyte count. In a multivariate logistic regression, a one-unit increase in cfDNA value was associated with 4.6% increased odds of severe AKI (OR = 1.046; p = 0.040). Finally, cfDNA significantly correlated with established NETs components, myeloperoxidase, and neutrophil elastase. Conclusion: Intravascular NETosis could be an important contributing factor in the development of microthrombosis and COVID-19-associated AKI. Further research is urgently needed to understand the role of NETosis in COVID-19 and evaluate therapeutic avenues for targeting this process.

Rise and fall of total mesorectal excision with lateral pelvic lymphadenectomy for rectal cancer: an updated systematic review and meta-analysis of 11,366 patients.

The role of lateral lymph node dissection (LLND) during total mesorectal excision (TME) for rectal cancer is still controversial. Many reviews were published on prophylactic LLND in rectal cancer surgery, some biased by heterogeneity of overall associated treatments. The aim of this systematic review and meta-analysis is to perform a timeline analysis of different treatments associated to prophylactic LLND vs no-LLND during TME for rectal cancer. METHODS: A literature search was performed in PubMed, SCOPUS and WOS for publications up to 1 September 2020. We considered RCTs and CCTs comparing oncologic and functional outcomes of TME with or without LLND in patients with rectal cancer. RESULTS: Thirty-four included articles and 29 studies enrolled 11,606 patients. No difference in 5-year local recurrence (in every subgroup analysis including preoperative neoadjuvant chemoradiotherapy), 5-year distant and overall recurrence, 5-year overall survival and 5-year disease-free survival was found between LLND group and non LLND group. The analysis of post-operative functional outcomes reported hindered quality of life (urinary, evacuatory and sexual dysfunction) in LLND patients when compared to non LLND. CONCLUSION: Our publication does not demonstrate that TME with LLND has any oncological advantage when compared to TME alone, showing that with the advent of neoadjuvant therapy, the advantage of LLND is lost. In this review, the most important bias is the heterogeneous characteristics of patients, cancer staging, different neoadjuvant therapy, different radiotherapy techniques and fractionation used in different studies. Higher rate of functional post-operative complications does not support routinely use of LLND.

A systematic review and meta-analysis of variants of the branches of the superior mesenteric artery: the Achilles heel of right hemicolectomy with complete mesocolic excision?

AIM: Dissection with subsequent ligation and resection of arteries at their origin (central vascular ligation) is essential for adequate oncological resection during right hemicolectomy with complete mesocolic excision. This technique is technically demanding due to the highly variable arterial pattern of the right colon. Therefore, this study aims to provide a comprehensive evidence-based assessment of the arterial vascular anatomy of the right colon. METHODS: A thorough systematic literature search through September 2020 was conducted on the electronic databases PubMed, Scopus and Web of Science to identify studies eligible for inclusion. Data were extracted and pooled into a meta-analysis using MetaXl software. RESULTS: A total of 41 studies (n = 4691 patients) were included. The ileocolic artery (ICA), right colic artery (RCA) and middle colic artery (MCA) were present in 99.7% (95% CI 99.4%-99.8%), 72.6% (95% CI 61.3%-82.5%) and 96.9% (95% CI 94.2%-98.8%) respectively of patients. Supernumerary RCA and MCA were observed in 3.2% and 11.4% respectively of all cases. The RCA shared a common trunk with the ICA and MCA in 13.2% and 17.7% respectively of patients. A retro-superior mesenteric vein course of the ICA and RCA was observed in 55.1% and 11.4% respectively of all cases. CONCLUSION: The vascular anatomy of the right colon displays several notable variations, namely the absence of some branches (RCA absent in 27.4% of cases), supernumerary branches, common trunks, and retro-superior mesenteric vein courses. These variations should be taken into consideration during right hemicolectomy with complete mesocolic excision to ensure adequate oncological resection while minimizing intra-operative complications.

Surgical anatomy of the accessory middle colic artery: a meta-analysis with implications for splenic flexure cancer surgery.

AIM: Surgical resection of splenic flexure cancers (SFCs) is technically demanding due to the complex regional anatomy, characterized by the presence of embryological adhesions, close proximity to the pancreas and spleen, and a highly heterogeneous arterial supply and lymphatic drainage. The accessory middle colic artery (AMCA) is increasingly being recognized as an important source of blood supply to the splenic flexure. The aim of this study is to determine the prevalence and anatomical features of the AMCA. METHOD: A systematic search of the scientific literature was conducted on PubMed and Embase from inception to November 2020 to identify potentially eligible studies. Data were extracted and prevalence was pooled into a meta-analysis using MetaXL and Meta-Analyst software. RESULTS: A total of 16 studies (n = 2203 patients) were included. The pooled prevalence (PP) of the AMCA was 25.4% (95% CI 18.1-33.4). Its prevalence was higher in patients without a left colic artery (LCA) (PP = 83.2%; 95% CI 70.4-93.1). The commonest origin for the AMCA was the superior mesenteric artery (PP = 87.9%; 95% CI 86.4-90.7). The AMCA shared a common trunk/gave rise to pancreatic branches in 23.1% of cases (95% CI 15.3-31.9). CONCLUSION: The AMCA contributes to the vascularization of the splenic flexure in approximately 25% of individuals, and may be an important feeder artery to SFCs, especially in the absence of a LCA. Preoperative identification of this artery is important to ensure optimal surgery for SFC and minimize complications.

Intracranial hemorrhage in coronavirus disease 2019 (COVID-19) patients.

BACKGROUND: Emerging evidence suggests that a subset of coronavirus disease 2019 (COVID-19) patients may present with or develop cerebrovascular disease during the course of hospitalization. Whereas ischemic stroke in COVID-19 patients has been well described, data on intracranial hemorrhage (ICH) in these patients is still limited. We, therefore, conducted a rapid systematic review of current scientific literature to identify and consolidate evidence of ICH in COVID-19 patients. METHODS: A systematic search of literature was conducted between November 1, 2019, and August 14, 2020, on PubMed and China National Knowledge Infrastructure (CNKI) to identify eligible studies. RESULTS: A total of 23 studies describing ICH in 148 COVID-19 patients were included. The pooled incidence of ICH in COVID-19 patients was 0.7% (95% CI 0.5-0.9), with low levels of inter-study heterogeneity observed (I2 = 33.6%, Cochran's Q = 12.05, p = 0.149). Most of the patients were elderly male patients (65.8%) with comorbidities, the most common being systemic hypertension (54%). Hemorrhage involving multiple cranial compartments was reported in 9.5% of cases. Single compartments were involved in the rest, with intraparenchymal hemorrhage (IPH) being the most common variety (62.6%) and intraventricular hemorrhage (IVH) the least common (1.4%). Half of these patients were on some form of anticoagulation. Overall, the mortality rate in the COVID-19 patients with ICH was about 48.6%. CONCLUSION: Although relatively uncommon among COVID-19 patients, ICH is associated with a high mortality rate. Early identification of patients at risk of developing ICH, particularly with comorbid conditions and on anticoagulant therapy, may be important to improve outcomes.

Arterial Thrombosis in Coronavirus Disease 2019 Patients: A Rapid Systematic Review.

BACKGROUND: Emerging evidence suggests that severe form of coronavirus disease 2019 (COVID-19) is mediated, in part, by a hypercoagulable state characterized by micro- and macro-vascular thrombotic angiopathy. Although venous thrombotic events in COVID-19 patients have been well described, data on arterial thrombosis (AT) in these patients is still limited. We, therefore, conducted a rapid systematic review of current scientific literature to identify and consolidate evidence of AT in COVID-19 patients. METHODS: A systematic search of literature was conducted between November 1, 2019, and June 9, 2020, on PubMed and China National Knowledge Infrastructure to identify potentially eligible studies. RESULTS: A total of 27 studies (5 cohort, 5 case series, and 17 case reports) describing arterial thrombotic events in 90 COVID-19 patients were included. The pooled incidence of AT in severe/critically ill intensive care unit-admitted COVID-19 patients across the 5 cohort studies was 4.4% (95% confidence interval 2.8-6.4). Most of the patients were male, elderly, and had comorbidities. AT was symptomatic in >95% of these patients and involved multiple arteries in approximately 18% of patients. The anatomical distribution of arterial thrombotic events was wide, occurring in limb arteries (39%), cerebral arteries (24%), great vessels (aorta, common iliac, common carotid, and brachiocephalic trunk; 19%), coronary arteries (9%), and superior mesenteric artery (8%). The mortality rate in these patients is approximately 20%. CONCLUSIONS: AT occurs in approximately 4% of critically ill COVID-19 patients. It often presents symptomatically and can affect multiple arteries. Further investigation of the underlying mechanism of AT in COVID-19 would be needed to clarify possible therapeutic targets.

Laparoscopic surgery during the COVID-19 pandemic: detection of SARS-COV-2 in abdominal tissues, fluids, and surgical smoke.

BACKGROUND: There are still concerns over the safety of laparoscopic surgery in coronavirus disease 2019 (COVID-19) patients due to the potential risk of viral transmission through surgical smoke/laparoscopic pneumoperitoneum. METHODS: We performed a systematic review of currently available literature to determine the presence of severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) in abdominal tissues or fluids and in surgical smoke. RESULTS: A total of 19 studies (15 case reports and 4 case series) comprising 29 COVID-19 patients were included. The viral RNA was positively identified in 11 patients (37.9%). The samples that tested positive include the peritoneal fluid, bile, ascitic fluid, peritoneal dialysate, duodenal wall, and appendix. Similar samples, together with the omentum and abdominal subcutaneous fat, tested negative in the other patients. Only one study investigated SARS-COV-2 RNA in surgical smoke generated during laparoscopy, reporting negative findings. CONCLUSIONS: There are conflicting results regarding the presence of SARS-COV-2 in abdominal tissues and fluids. No currently available evidence supports the hypothesis that SARS-COV-2 can be aerosolized and transmitted through surgical smoke. Larger studies are urgently needed to corroborate these findings.

Cancer is associated with coronavirus disease (COVID-19) severity and mortality: A pooled analysis.

BACKGROUND: Coronavirus disease 2019 (COVID-19) is a rapidly escalating pandemic that has spread to many parts of the world. As such, there is urgent need to identify predictors of clinical severity in COVID-19 patients. This may be useful for early identification of patients who may require life-saving interventions. In this meta-analysis, we evaluated whether malignancies are associated with a significantly enhanced odds of COVID-19 severity and mortality. METHOD: A systematic search of literature was conducted between November 1, 2019, to May 26th, 2020 on PubMed and China National Knowledge Infrastructure (CNKI) to identify studies reporting data on cancers in patients with or without severe COVID-19 were included. The primary outcome of interest was the association between malignancies and COVID-19 severity, while the secondary outcome was the association between malignancies and COVID-19 mortality. Data were pooled into a meta-analysis to estimate pooled odds ratio (OR) with 95% confidence interval (95% CI) for either outcome. RESULTS: A total of 20 studies (n = 4549 patients) were included. Overall, malignancies were found to be associated with significantly increased odds of COVID-19 severity (OR = 2.17; 95% CI 1.47-3.196; p < 0.001) and mortality (OR = 2.39; 95% CI 1.18-4.85; p = 0.016). No heterogeneity was observed for both outcomes (Cochran's Q = 6.558, p = 0.922, I2 = 0% and Cochran's Q = 2.91, p = 0.71, I2 = 0% respectively). CONCLUSION: Malignancies were significantly associated with a 2-fold increase in the odds of developing severe COVID-19 disease, as well as mortality. Larger studies are needed to corroborate these findings. These patients should be closely monitored for any signs of unfavorable disease progression.

Surgical anatomy of sigmoid arteries: A systematic review and meta-analysis.

BACKGROUND: The purpose of this systematic review and meta-analysis was to determine the prevalence of the number of sigmoid arteries (SA) and variations in their origins. METHODS: A thorough systematic search of literature through February 2020 was conducted on major electronic databases to identify eligible studies. Data were extracted and pooled into a meta-analysis using Metafor package in R. The primary outcome was the variations in the SA origin (according to modified Zebrowski classification), and the secondary outcome was the prevalence of the number of SA. RESULTS: A total of 22 studies (n = 2653 patients) were included. Type 1 modified Zebrowski (separated origins or common trunk of the SA originating from descending recto-sigmoid trunk (DRST)) was the most common origin type of the SA (pooled prevalence estimate (PPE) = 49.67% (95% CI 32. 67- 66.71)), while type 3 (separated origins or common trunk of 1 or 2 SA originating from DRST or superior rectal artery (SRA) and 1 or 2 SA originating from DRST or SRA) was the least common (PPE = 0.18%; 95% CI 0.00-2.82)). Of the Type 1 variants, the not specified (N.S) variant was by far the most prevalent. The number of SA ranged from one to five, with three being the mode (PPE = 42.3%). CONCLUSION: This is the most comprehensive analysis of arterial vascular anatomy of the sigmoid colon. In light of the highly variable anatomical pattern displayed by the SA, thorough pre-operative knowledge of their anatomy can be crucial in minimizing incidences of iatrogenic injury.

The prevalence of the Rouviere's sulcus: A meta-analysis with implications for laparoscopic cholecystectomy.

Rouvière's sulcus (RS) is increasingly being recognized as an important extra-biliary landmark during laparoscopic cholecystectomy (LC). The aim of this study was to conduct a systematic analysis of the prevalence and morphological types of RS. A systematic search was conducted through the major databases PubMed, ScienceDirect, Google Scholar, China National Knowledge Infrastructure (CNKI), SciELO, and the Cochrane Library to identify studies eligible for inclusion. The data were extracted and pooled into a random-effects meta-analysis using STATA software. The primary and secondary outcomes of the study were the pooled prevalence of RS and its morphological types, respectively. A total of 23 studies (n = 4,495 patients) were included. The overall pooled prevalence of RS was 83% (95% confidence interval [CI] [78, 87]). There were no significant differences in prevalence between cadaveric studies (82%, 95% CI [76, 87]) and laparoscopic studies (83%, 95% CI [77, 88]). The open RS constituted 66% (95% CI [61, 71]) of all cases, while the closed type was present in 34% (95% CI [29, 39]). RS is a relatively constant anatomical structure that can be reliably identified in most patients undergoing cholecystectomy. It can therefore be used as a fixed extra-biliary landmark for the appropriate site at which to start dissecting during LC to help prevent iatrogenic bile duct injury.

A systematic review and meta-analysis of iliocapsularis muscle: an important landmark in orthopedic surgery.

PURPOSE: Iliocapsularis (IC) is a small muscle overlying the capsule of the hip joint. Although recent attention is being given to this muscle by orthopedic surgeons who encounter it during the anterior approach to total hip arthroplasty, little is known about its anatomical features. The aim of this study was to review the anatomy of IC, and describe its' origin, insertion, blood supply, innervation, muscle fiber characteristics and size. The function, clinical relevance and comparative anatomy of IC were also appraised. METHODS: Using Evidence-Based Anatomy methodology, electronic databases were searched with the terms "iliocapsularis", "iliacus minor", "iliotrochantericus", and "ilioinfratrochantericus" to identify eligible studies. RESULTS: Six studies (n = 287 lower limbs) examining the anatomy of IC were included. The pooled prevalence (PP) of the IC was 98.7% (95% CI 96.5-100.0). It arises from the inferior facet of the anterior inferior iliac spine (AIIS) and attaches inferior to the lesser trochanter. Attached to the anteromedial capsule along its entire length, IC has the largest capsular contribution of any of the hip muscles (73.8 ± 27.3 × 16.1 ± 4.4 mm). Thus, it is an important landmark in anterior surgical approaches to the hip joint. CONCLUSION: The anatomy of IC is becoming more relevant with the increasing use of anterior approaches to hip surgery. With attachments to the AIIS, the lesser trochanter as well as the length of the capsule, this muscle is an important landmark in total hip arthroplasty. LEVEL OF EVIDENCE: Level V.

Prevalence and pubo-umbilical index of pyramidalis muscle in a select Kenyan population.

PURPOSE: Pyramidalis is a lower anterior abdominal wall muscle that is considered vestigial and shows variations in prevalence and size. It's been utilized as an anatomical landmark and harvested for use in various surgical procedures. Despite knowledge of its clinical importance, data on the prevalence of pyramidalis remain absent from the Kenyan population with few studies globally reporting on its pubo-umbilical index. We therefore aimed to determine the prevalence and relative lengths (pubo-umbilical index) of pyramidalis muscle in a sample Kenyan population. MATERIALS AND METHODS: Fifty-two cadavers (41 males, 11 females) from the Department of Human Anatomy, University of Nairobi were used. Prevalence and length of the muscle (l) were established, and the distance between pubic symphysis and umbilicus (L) measured and used to calculate pubo-umbilical index (l/L ×100%). Independent and paired T tests were done, using SPSS® version 22. A p value of ≤ 0.05 was considered statistically significant at a 95% confidence interval. RESULTS: Pyramidalis was present in 84% (44) of cadavers; 83% (43) bilaterally, 2% (1) unilaterally, and 85.4% (35) in males, 81.8% (9) in females. Mean length in males and females was 71.8 ± 35 mm and 63.5 ± 37.5 mm, respectively. Mean pubo-umbilical index was 38% ± 18 (39 % ± 18 males, 35% ± 19 females). No statistically significant difference was found. CONCLUSION: Pyramidalis is a highly prevalent muscle in the Kenyan population and, hence, could be exploited for its clinical and surgical utilities. The muscle terminates largely within the 2nd quarter (25-50%) of the infra-umbilical linea alba measured from pubic symphysis. Its pubo-umbilical index would be useful to surgeons making midline infra-umbilical incisions and performing procedures involving the muscle.

Anatomical variations of the pyramidalis muscle: a systematic review and meta-analysis.

PURPOSE: To provide a comprehensive evidence-based assessment of the anatomical characteristics of the pyramidalis muscle (PM). MATERIALS AND METHODS: A thorough systematic search of the literature through August 31st 2020 was conducted on major electronic databases PubMed, Scopus and Web of Science (WOS) to identify studies eligible for inclusion. Data were extracted and pooled into a meta-analysis using MetaFor package in R and MetaXL. A random-effects model was applied. The primary outcome of interest was the prevalence of PM. The secondary outcomes were the dimensions (length and width) of the PM. RESULTS: A total of 11 studies (n = 787 patients; 1548 sides) were included in the meta-analysis. The multinomial pooled prevalence estimate (PPE) for a bilateral absence of the PM was 11.3% (95% CI [7.2%, 16.2%], 82.3% (95% CI [76.2%, 87.6%]) for a bilateral presence, and 6.3% (95% CI [3.3%, 10.2%]) for a unilateral presence. Of four studies (n = 37 patients) that reported the side of a unilateral presence, the PPE of a unilateral right-side presence was 42.2% (95% CI [23.0%, 62.3%]) compared to 57.8% for a unilateral left-side presence (95% CI [37.7%, 77.0%]). The mean length of the PM displayed high levels of heterogeneity, ranging from 3.12 to 12.50 cm. CONCLUSION: The pyramidalis muscle is a rather constant anatomical structure being present in approximately 90% of individuals.

Computed Tomography Scan Assessment of the Anatomy of the Pterygomaxillary Junction and Its Relevance in Le Fort I Osteotomy.

Knowledge of the morphometry and types of pterygomaxillary junction (PMJ) during Le-Fort I osteotomy is an important consideration in the reduction of intraoperative complications. The PMJ is known to display population variations and with the recent increase in these surgical interventions in Kenya, a detailed description of the PMJ is warranted. Computed tomography scan images of PMJ obtained from 63 patients were analyzed at the level of the posterior nasal spine to assess types and the morphometry of the PMJ. A fissure type of PMJ was present in 65.9% (83/126 sides) while a synostosis type was present in 34.1% (43/126). Bilateral fissures were found in 58.73% (37/63), bilateral synostosis in 26.98% (17/63), and an asymmetric PMJ in 15.25% (9/63). The average height, width, and thickness of the PMJ were 17.45 ±â€Š5.26 mm, 10.24 ±â€Š1.97 mm, and 6.40 ±â€Š1.97 mm respectively. Males had a significantly greater height (P = 0.003) and width (P = 0.000). The average width was greater in cases with a synostosis as compared with those with a fissure (P = 0.019). Average distance of greater palatine canal was 40.41 ±â€Š2.28 mm and 7.19 ±â€Š2.20 mm from the piriform rim and the pterygoid fossa respectively. The PMJ among Kenyans is characterized by a higher occurrence of synostosis, greater height, and thickness compared with previous findings from other populations. The results of this study can be helpful for surgeons in selecting the most appropriate techniques to achieve successful pterygomaxillary disjunction and minimize avoid attendant complications such as vascular and nerve injuries.

Surgical anatomy of the external branch of the superior laryngeal nerve: a systematic review and meta-analysis.

PURPOSE: To provide a comprehensive evidence-based assessment of the anatomical characteristics of the external branch of the superior laryngeal nerve (EBSLN). MATERIALS AND METHODS: A thorough systematic search was performed on the major electronic databases PubMed, EMBASE, Cochrane library, and ScienceDirect to identify eligible studies. Data were extracted and pooled into a meta-analysis. The primary outcomes were the EBSLN identification rate (total number of EBSLN identified divided by the total number of dissected hemilarynges) and the prevalence of various EBSLN types. RESULTS: A total of 56 studies (n = 13,444 hemilarynges) were included. The overall pooled EBSLN identification rate was 89.24% (95% CI 85.49-92.49). This rate was higher for cadaveric (95.00%; 95% CI 89.73-99.35) compared to that reported in intraoperative studies (86.99%; 95% CI 82.37-91.01). Significantly higher identification rates were reported for studies in which intraoperative nerve monitoring was used (95.90%; 95% CI 94.30-97.25) compared to those which only relied on direct visual identification of the EBSLN (76.56%; 95% CI 69.34-83.08). Overall, Cernea type IIa (nerves crossing the superior thyroid artery less than 1 cm above the upper edge of the superior thyroid pole) and Friedman type 1 (nerves running their entire course superficial to the inferior pharyngeal constrictor) were the most prevalent (41.84%; 95% CI 33.28-48.08 and 50%; 95% CI 29.90-65.62, respectively). The combined prevalence of Cernea IIa and IIb (nerves crossing the superior thyroid artery below the upper edge of the superior thyroid pole) was higher in intraoperative studies compared to that in cadaveric studies (64.3% vs 49.4%). The EBSLN coursed medial to the superior thyroid artery in 70.98% (95% CI 55.14-84.68) of all cases. CONCLUSION: The use of intraoperative nerve monitoring improves EBSLN identification rates. In light of the highly variable anatomical patterns displayed by the EBSLN, thorough pre-operative knowledge of its anatomy can be crucial in minimizing incidences of its iatrogenic injury.