Outcomes of extracorporeal life support for respiratory failure in children with primary immunodeficiencies.

OBJECTIVE: Extracorporeal Membrane Oxygenation (ECMO) may serve as a life-saving rescue therapy in critically ill children with respiratory failure. While survival rates of ECMO in children with secondary immunodeficiency is considered relatively poor, survival rates in children with primary immunodeficiencies (PID) has yet to be thoroughly investigated. DESIGN: Retrospective analysis of prospectively collected data from children (29 days-18 years old). PID patients were identified by using International Classification of Diseases (ICD) codes. SETTING: Data were retrieved from Extracorporeal Life Support Organization Registry (1989-2018). INTERVENTIONS: ECMO for a pulmonary support indication. The survival-to-discharge rate was calculated and factors influencing outcomes were compared between survivors and non-survivors. MEASUREMENTS AND MAIN RESULTS: A total of 73 eligible ECMO runs were included. The survival-to-discharge rate in pediatric PID patients was 45.2%. No differences were noted in survival based on type of immunodeficiency (p = 0.42) or decade of support (p = 0.98). There was no difference in the rate of pre-ECMO infection in survivors versus non-survivors (p = 0.69). The survival-to-discharge rate in patients with a culture positive infection during the ECMO run was 45.0% versus 45.3% in those with no infection (p = 0.98). In multivariate analysis, only cardiac complications (OR 5.09, 95% CI: 1.15-22.53), pulmonary complications (OR: 13.00, 95% CI: 1.20-141.25), and neurologic complications (OR: 9.86, 95% CI: 1.64-59.21) were independently associated with increased mortality. CONCLUSION: Children with a PID who require extracorporeal life support due to respiratory failure have a reasonable chance of survival and should be considered candidates for ECMO. The presence of a pre-ECMO infection should not be considered an ECMO contraindication.

Complement levels at admission as a reflection of coronavirus disease 2019 (COVID-19) severity state.

Complement system hyperactivation has been proposed as a potential driver of adverse outcomes in severe acute respiratory syndrome coronavirus 2 infected patients, given prior research of complement deposits found in tissue and blood samples, as well as evidence of clinical improvement with anticomplement therapy. Its role in augmenting thrombotic microangiopathy mediated organ damage has also been implicated in coronavirus disease 2019 (COVID-19). This study aimed to examine associations between complement parameters and progression to severe COVID-19 illness, as well as correlations with other systems. Blood samples of COVID-19 patients presenting to the emergency department (ED) were analyzed for a wide panel of complement and inflammatory biomarkers. The primary outcome was COVID-19 severity at index ED visit, while the secondary outcome was peak disease severity over the course of illness. Fifty-two COVID-19 patients were enrolled. C3a (p = 0.018), C3a/C3 ratio (p = 0.002), and sC5b-9/C3 ratio (p = 0.021) were significantly elevated in with severe disease at ED presentation. Over the course of illness, C3a (p = 0.028) and C3a/C3 ratio (p = 0.003) were highest in the moderate severity group. In multivariate regression controlled for confounders, complement hyperactivation failed to predict progression to severe disease. C3a, C3a/C3 ratio, and sC5b-9/C3 ratio were correlated positively with numerous inflammatory biomarkers, fibrinogen, and VWF:Ag, and negatively with plasminogen and ADAMTS13 activity. We found evidence of complement hyperactivation in COVID-19, associated with hyperinflammation and thrombotic microangiopathy. Complement inhibition should be further investigated for potential benefit in patients displaying a hyperinflammatory and microangiopathic phenotype.

The anti-inflammatory cytokine response characterized by elevated interleukin-10 is a stronger predictor of severe disease and poor outcomes than the pro-inflammatory cytokine response in coronavirus disease 2019 (COVID-19).

OBJECTIVES: Severe coronavirus disease 2019 (COVID-19) is associated with a dysregulated immune state. While research has focused on the hyperinflammation, little research has been performed on the compensatory anti-inflammatory response. The aim of this study was to evaluate the anti-inflammatory cytokine response to COVID-19, by assessing interleukin-10 (IL-10) and IL-10/lymphocyte count ratio and their association with outcomes. METHODS: Adult patients presenting to the emergency department (ED) with laboratory-confirmed COVID-19 were recruited. The primary endpoint was maximum COVID-19 severity within 30 days of index ED visit. RESULTS: A total of 52 COVID-19 patients were enrolled. IL-10 and IL-10/lymphocyte count were significantly higher in patients with severe disease (p<0.05), as well as in those who developed severe acute kidney injury (AKI) and new positive bacterial cultures (all p≤0.01). In multivariable analysis, a one-unit increase in IL-10 and IL-10/lymphocyte count were associated with 42% (p=0.031) and 32% (p=0.013) increased odds, respectively, of severe COVID-19. When standardized to a one-unit standard deviations scale, an increase in the IL-10 was a stronger predictor of maximum 30-day severity and severe AKI than increases in IL-6 or IL-8. CONCLUSIONS: The hyperinflammatory response to COVID-19 is accompanied by a simultaneous anti-inflammatory response, which is associated with poor outcomes and may increase the risk of new positive bacterial cultures. IL-10 and IL-10/lymphocyte count at ED presentation were independent predictors of COVID-19 severity. Moreover, elevated IL-10 was more strongly associated with outcomes than pro-inflammatory IL-6 or IL-8. The anti-inflammatory response in COVID-19 requires further investigation to enable more precise immunomodulatory therapy against SARS-CoV-2.

Lactate dehydrogenase levels predict coronavirus disease 2019 (COVID-19) severity and mortality: A pooled analysis.

Coronavirus disease 2019 (COVID-19) infection has now reached a pandemic state, affecting more than a million patients worldwide. Predictors of disease outcomes in these patients need to be urgently assessed to decrease morbidity and societal burden. Lactate dehydrogenase (LDH) has been associated with worse outcomes in patients with viral infections. In this pooled analysis of 9 published studies (n = 1532 COVID-19 patients), we evaluated the association between elevated LDH levels measured at earliest time point in hospitalization and disease outcomes in patients with COVID-19. Elevated LDH levels were associated with a ~6-fold increase in odds of developing severe disease and a ~16-fold increase in odds of mortality in patients with COVID-19. Larger studies are needed to confirm these findings.

The prevalence and anatomy of parathyroid glands: a meta-analysis with implications for parathyroid surgery.

PURPOSE: The anatomy of parathyroid glands (PTG) is highly variable in the population. The aim of this study was to conduct a systematic analysis on the prevalence and location of PTG in healthy and hyperparathyroidism (HPT) patients. METHODS: An extensive search of the major electronic databases was conducted to identify all studies that reported relevant data on the number of PTG per patient and location of PTG. The data was extracted from the eligible studies and pooled into a meta-analysis. RESULTS: The overall analysis of 26 studies (n = 7005 patients; n = 23,519 PTG) on the number of PTG showed that 81.4% (95% CI 65.4-85.8) of patients have four PTG. A total of 15.9% of PTG are present in ectopic locations, with 11.6% (95% CI 5.1-19.1) in the neck and 4.3% (95% CI 0.7-9.9) in mediastinum. The subgroup analysis of ectopic PTG showed that 51.7% of ectopic PTG in the neck are localized in retroesophageal/paraesophageal space or in the thyroid gland. No significant differences were observed between the healthy and HPT patients and cadaveric and intraoperative studies. CONCLUSIONS: Knowledge regarding the prevalence, location, and anatomy of PTG is essential for surgeons planning for and carrying out parathyroidectomies, as any unidentified PTG, either supernumerary or in ectopic location, can result in unsuccessful treatment and need for reoperation.

Tolerability and safety of long-term rituximab treatment in systemic inflammatory and autoimmune diseases.

Rituximab, an anti-CD20 monoclonal antibody causing selective B-cell depletion, is used for various systemic inflammatory and autoimmune diseases (SIADs). Long-term safety data on rituximab are limited. The objectives of this study were to evaluate the long-term safety and tolerability of rituximab treatment for SIADs. A retrospective, single-center observational study including all patients ≥ 16 years treated with rituximab for SIADs was performed. The electronic medical records were reviewed, and data concerning indication and duration of rituximab treatment, prior and concurrent immunosuppressive therapy, and adverse events such as infections requiring hospitalization, dysgammaglobulinemia and end organ damage, were collected. A total of 70 patients were included, with a median treatment duration of 54 months, ranging 30-138 months. The most common indications for rituximab treatment were granulomatosis with polyangiitis (22.9%), primary Sjögren's syndrome (20.0%) and systemic lupus erythematosus (14.3%). Infections and persistent dysgammaglobulinemia were the most common adverse events, occurring in 34.3% and 25.7%, respectively. A total of 64 infections were observed in 24 (34.3%) patients, including 1 case of fatal infection. Seventeen patients performed B-cell quantitation during the first 2 years following discontinuation, of which only four (19.0%) demonstrated B-cell reconstitution. End organ damage occurred in two patients, presenting as pyoderma gangrenosum and interstitial pneumonitis. No opportunistic infections were observed. Three patients died during the observational period, of which one was due to lethal infection. This study presents observational data with long treatment duration. It demonstrates that long-term rituximab treatment is relatively well tolerated, and that no cumulative side effects were observed.

Incidence, Risk Factors, and Comorbidities of Vocal Cord Paralysis After Surgical Closure of a Patent Ductus Arteriosus: A Meta-analysis.

Surgical closure of a patent ductus arteriosus (PDA) is considered standard treatment for symptomatic neonates refractory to medical therapy. Sometimes, iatrogenic injury to the left recurrent laryngeal nerve during the procedure can result in vocal cord paralysis (VCP). This study aimed to estimate the incidence of VCP in patients after surgical PDA closure and to identify any associated risk factors and morbidities associated with VCP in the preterm infant population. A thorough search of the major electronic databases was conducted to identify studies eligible for inclusion into this meta-analysis. Studies reporting data on the incidence of VCP (primary outcomes) or risk factors and morbidities associated with VCP in premature infant population (secondary outcomes) were included. A total of 33 studies (n = 4887 patients) were included into the analysis. Overall pooled incidence estimate of VCP was 7.9% (95%CI 5.3-10.9). The incidence of VCP after PDA closure was significantly much higher in premature infants (11.2% [95%CI 7.0-16.3]) than in non-premature patients (3.0% [95%CI 1.5-4.9]). The data showed that VCP was most common after surgical ligation and in studies conducting universal laryngoscopy scoping. The risk factors for postoperative VCP in preterm infants included birth weight and gestational age. In addition, VCP was significantly associated with the occurrence of bronchopulmonary dysplasia, gastrostomy tube insertion, and increased duration of mechanical ventilation. Vocal cord paralysis remains a frequent complication of surgical closure of a PDA, especially in premature neonates, and is associated with significant post-procedural complications.

Purple urine bag syndrome. / Lilla urinpose-syndrom.

BACKGROUND: Purple urine bag syndrome (PUBS) can occur in cases of bacteriuria with species expressing enzymes capable of converting tryptophan metabolites to red and blue pigments which are excreted in urine, leaving a characteristic purple colour. Risk factors include urinary catheterisation, constipation and chronic kidney disease. Treatment includes catheter replacement, and antibiotics in case of urinary tract infection. CASE PRESENTATION: A man in his 70s with myelodysplastic syndrome, stage 5 chronic kidney disease and chronic indwelling urinary catheterisation due to benign prostatic hyperplasia was admitted for transfusion for symptomatic anaemia. On the second day of hospitalisation, his urine turned purple. There was no sign of transfusion reaction, haemoglobinuria, myoglobinuria or bilirubinuria. Urine cultures were positive for Proteus vulgaris and Enterococcus faecalis, two species associated with PUBS. INTERPRETATION: The constellation was consistent with PUBS. His bacteriuria was considered colonisation not requiring antibiotic treatment. The catheter was replaced and the urine colour returned to normal.

Tubulointerstitial nephritis and uveitis syndrome. / Tubulointerstitiell nefritt og uveitt-syndrom.

BACKGROUND: Uveitis and acute renal failure can be seen in various immune-mediated systemic diseases. Here we present a case of a young man with a rare inflammatory oculorenal syndrome. CASE REPORT: A man in his thirties was admitted with a constellation of fatigue, flank pain, weight loss and bilateral acute anterior uveitis. Laboratory tests showed anaemia, leukocytosis with eosinophilia, as well as elevated creatinine and C-reactive protein, and urine analyses demonstrated mild proteinuria. Work-up excluded sarcoidosis, Sjögren's syndrome, systemic lupus erythematosus, ANCA-associated vasculitides, Behçet disease, spondyloarthritis and infection. Renal biopsy showed severe tubulointerstitial nephritis. INTERPRETATION: Following exclusion of the abovementioned disorders, a diagnosis of tubulointerstitial nephritis and uveitis (TINU) syndrome was made. TINU syndrome is a rare inflammatory disorder which can be diagnosed in patients presenting with uveitis and tubulointerstitial nephritis after exclusion of other causes of similar oculorenal involvement.

Consensus guidelines for the uniform reporting of study ethics in anatomical research within the framework of the anatomical quality assurance (AQUA) checklist.

Unambiguous reporting of a study's compliance with ethical guidelines in anatomical research is imperative. As such, clear, universal, and uniform reporting guidelines for study ethics are essential. In 2016, the International Evidence-Based Anatomy Working group in collaboration with international partners established reporting guidelines for anatomical studies, the Anatomical Quality Assurance (AQUA) Checklist. In this elaboration of the AQUA Checklist, consensus guidelines for reporting study ethics in anatomical studies are provided with in the framework of the AQUA Checklist. The new guidelines are aimed to be applicable to research across the spectrum of the anatomical sciences, including studies on both living and deceased donors. The authors hope the established guidelines will improve ethical compliance and reporting in anatomical research. Clin. Anat. 31:521-524, 2018. © 2018 Wiley Periodicals, Inc.

Systematic reviews versus narrative reviews in clinical anatomy: Methodological approaches in the era of evidence-based anatomy.

Two main types of review articles with distinct characteristics and goals are commonly found in the scientific literature: systematic reviews and narrative (also called expert or traditional) reviews. Narrative reviews are publications that describe and discuss the state of science on a specific topic or theme from a theoretical and contextual point of view with little explicit structure for gathering and presenting evidence. Systematic reviews are overviews of the literature undertaken by identifying, critically appraising and synthesizing the results of primary research studies using an explicit methodological approach. With the recent rise of evidence-based anatomy, important questions arise with respect to the utility of narrative reviews in clinical anatomy. The goal of this perspective article is to address the key differences between narrative and systematic reviews in the context of clinical anatomy, to provide guidance on which type of review is most appropriate for a specific issue, and to summarize how the two types of reviews can work in unison to enhance the quality of anatomical research and its delivery to clinicians and anatomists alike. Clin. Anat. 31:364-367, 2018. © 2018 Wiley Periodicals, Inc.

[Cardiac sarcoidosis]. / Kardial sarkoidose.

Sarcoidosis is characterised by granulomatous inflammation in one or more organs, including the heart. Cardiac sarcoidosis generally has non-specific symptoms, and the disease is often diagnosed at a late stage. The condition is associated with cardiomyopathy and arrhythmia and may be fatal.

Variations in the Arterial Blood Supply to the Penis and the Accessory Pudendal Artery: A Meta-Analysis and Review of Implications in Radical Prostatectomy.

PURPOSE: The aim of this meta-analysis was to analyze the available literature and provide comprehensive data on the prevalence and variations of the accessory pudendal artery and the 3 types of penile blood supply, including type 1-internal pudendal artery only, type 2-internal pudendal artery and accessory pudendal artery, and type 3-accessory pudendal artery only. MATERIALS AND METHODS: We performed an extensive search of the major databases and identified 23 studies in a total of 4,945 patients suitable for inclusion in this meta-analysis. Studies eligible for inclusion included cadaveric, imaging or intraoperative studies. Extracted data were pooled into a meta-analysis with a random effects model using MetaXL, version 5.0 (EpiGear International, Sunrise Beach, Queensland, Australia). The chi-square test and Higgins I2 statistics were used to assess heterogeneity among included studies. RESULTS: Our findings revealed that the most common type was type 1 with a pooled prevalence estimate of 61.9%, followed by types 2 and 3 with a pooled prevalence estimate of 32.8% and 5.4%, respectively. In our analysis of the accessory pudendal artery the vessel was present in 28.5% of patients. When present, unilateral accessory pudendal arteries were most common (pooled prevalence estimate 72.5%) or they were present on the right or the left side (pooled prevalence estimate 48.0% or 52.0%, respectively). They most commonly originated from the obturator artery and the inferior vesical artery (pooled prevalence estimate 48.9% and 29.6%, respectively). The most common type was apical accessory pudendal arteries (pooled prevalence estimate 60.9%). CONCLUSIONS: A penile blood supply originating at least in part from an accessory pudendal artery represents more than a third of cases. Based on the anatomical findings when an accessory pudendal artery is present, we advocate attempted preservation of the vessel during radical prostatectomy to best maintain the penile arterial blood supply, especially in patients with type 3 or in older patients with type 2.

The current state of intermittent intraoperative neural monitoring for prevention of recurrent laryngeal nerve injury during thyroidectomy: a PRISMA-compliant systematic review of overlapping meta-analyses.

PURPOSE: Recurrent laryngeal nerve (RLN) injury is one of the most common and detrimental complications following thyroidectomy. Intermittent intraoperative nerve monitoring (I-IONM) has been proposed to reduce prevalence of RLN injury following thyroidectomy and has gained increasing acceptance in recent years. METHODS: A comprehensive database search was performed, and data from eligible meta-analyses meeting the inclusion criteria were extracted. Transient, permanent, and overall RLN injuries were the primary outcome measures. Quality assessment via AMSTAR, heterogeneity appraisal, and selection of best evidence was performed via a Jadad algorithm. RESULTS: Eight meta-analyses met the inclusion criteria. Meta-analyses included between 6 and 23 original studies each. Via utilization of the Jadad algorithm, the selection of best evidence resulted in choosing of Pisanu et al. (Surg Res 188:152-161, 2014). Five out of eight meta-analyses demonstrated non-significant (p > 0.05) RLN injury reduction with the use of I-IONM versus nerve visualization alone. CONCLUSIONS: To date, I-IONM has not achieved a significant level of RLN injury reduction as shown by the meta-analysis conducted by Pisanu et al. (Surg Res 188:152-161, 2014). However, most recent developments of IONM technology including continuous vagal IONM and concept of staged thyroidectomy in case of loss of signal on the first side in order to prevent bilateral RLN injury may provide additional benefits which were out of the scope of this study and need to be assessed in further prospective multicenter trials.

Development of the anatomical quality assessment (AQUA) tool for the quality assessment of anatomical studies included in meta-analyses and systematic reviews.

Critical appraisal of anatomical studies is essential before the evidence from them undergoes meta-epidemiological synthesis. However, no instrument for appraising anatomical studies with inherent applicability to different study designs is available. We aim to develop a generic yet comprehensive tool for assessing the quality of anatomical studies using a formal consensus method. The study steering committee formulated an initial conceptual design and generated items for a preliminary tool on the basis of a literature review and expert opinion. A Delphi procedure was then adopted to assess the validity of the preliminary tool. Feedback from the Delphi panelists was used to improve it. The Delphi procedure involved 12 experts in anatomical research. It comprised two rounds, after which unanimous consensus was reached about the items to be included. The preliminary tool consisted of 20 items, which were phrased as signaling questions and organized into five domains: 1. Aim and subject characteristics, 2. Study design, 3. Characterization of methods, 4. Descriptive anatomy, and 5. Results reporting. Each domain was set to end with a risk of bias question. Following round 1, some of the items underwent major revision, although agreement was reached regarding inclusion of all the domains and signaling questions in the preliminary tool. The tool was revised only for minor language inaccuracies after round 2. The AQUA Tool was designed to assess the quality and reliability of anatomical studies. It is currently undergoing a validation process. Clin. Anat. 30:6-13, 2017. © 2016 Wiley Periodicals, Inc.

Variations in the origin of the deep femoral artery: A meta-analysis.

The deep femoral artery (DFA) is the largest branch of the femoral artery (FA) and is responsible for vascularization of the thigh muscles. Knowledge of the anatomical variations in its origin point is important for surgeons and interventional radiologists. The aim of our study was to provide a comprehensive evidence-based assessment of its anatomical properties. An extensive search through the major electronic databases was conducted to find all articles reporting data on the anatomical characteristics of the DFA. No date limits or language restrictions were imposed. A total of 25 articles (n = 2,502 lower limbs) were included in the meta-analysis. Six different patterns of origin of the DFA from the FA were identified, the most common type being a posterior origin (38.8%, 95% CI 22.8-49.5%). The DFA most commonly branched off in the proximal third of the thigh, with a prevalence of 47.6% (95% CI 35.8-59.2%). The pooled mean distance of the DFA from its point of origin to the mid-inguinal point was 41.15 mm (95% CI 32.39-53.73). The point and level of origin of the DFA from the FA varies widely in the general population. Owing to this variability, accurate anatomical knowledge regarding the DFA is crucial for clinicians if iatrogenic injuries are to be avoided during procedures in the femoral region. Clin. Anat. 30:106-113, 2017. © 2016 Wiley Periodicals, Inc.

Development of the Anatomical Quality Assurance (AQUA) checklist: Guidelines for reporting original anatomical studies.

The rise of evidence-based anatomy has emphasized the need for original anatomical studies with high clarity, transparency, and comprehensiveness in reporting. Currently, inconsistencies in the quality and reporting of such studies have placed limits on accurate reliability and impact assessment. Our aim was to develop a checklist of reporting items that should be addressed by authors of original anatomical studies. The study steering committee formulated a preliminary conceptual design and began to generate items on the basis of a literature review and expert opinion. This led to the development of a preliminary checklist. The validity of this checklist was assessed by a Delphi procedure, and feedback from the Delphi panelists, who were experts in the area of anatomical research, was used to improve it. The Delphi procedure involved 12 experts in anatomical research. It comprised two rounds, after which unanimous consensus was reached regarding the items to be included in the checklist. The steering committee agreed to name the checklist AQUA. The preliminary AQUA Checklist consisted of 26 items divided into eight sections. Following round 1, some of the items underwent major revision and three new ones were introduced. The checklist was revised only for minor language inaccuracies after round 2. The final version of the AQUA Checklist consisted of the initial eight sections with a total of 29 items. The steering committee hopes the AQUA Checklist will improve the quality and reporting of anatomical studies. Clin. Anat. 30:14-20, 2017. © 2016 Wiley Periodicals, Inc.

Median and ulnar nerve anastomoses in the upper limb: A meta-analysis.

INTRODUCTION: The most frequently described anomalous neural connections between the median and ulnar nerves in the upper limb are: Martin-Gruber anastomosis (MGA), Marinacci anastomosis (MA), Riche-Cannieu anastomosis (RCA), and Berrettini anastomosis (BA). The reported prevalence rates and characteristics of these anastomoses vary significantly between studies. METHODS: A search of electronic databases was performed to identify all eligible articles. Anatomical data regarding the anastomoses were pooled into a meta-analysis using MetaXL 2.0. RESULTS: A total of 58 (n = 10,562 upper limbs) articles were included in the meta-analysis. The pooled prevalences were: MGA, 19.5% (95% confidence interval [CI], 16.2%-23.1%); MA, 0.7% (95% CI, 0.1%-1.7%); RCA, 55.5% (95% CI, 30.6%-79.1%); and BA, 60.9% (95% CI, 36.9%-82.6%). The results also showed that MGA was more commonly found unilaterally (66.8%), on the right side (15.7%), following an oblique course (84.8%), and originating from the anterior interosseous nerve with a prevalence of 57.6%. CONCLUSIONS: As anastomoses between the median and ulnar nerves occur commonly, detailed anatomical knowledge is essential for accurate interpretation of electrophysiological findings and reducing the risk of iatrogenic injuries during surgical procedures. Muscle Nerve 54: 36-47, 2016.

Extralaryngeal branching of the recurrent laryngeal nerve: a meta-analysis of 28,387 nerves.

INTRODUCTION: The recurrent laryngeal nerves (RLN) are branches of the vagus nerve that go on to innervate most of the intrinsic muscles of the larynx. Historically, the RLN has been considered to branch after it enters the larynx, but numerous studies have demonstrated that it often branches before. The wide variability of this extralaryngeal branching (ELB) has significant implications for the risk of iatrogenic injury. We aimed to assess the anatomical characteristics of ELB comprehensively. METHODS: Articles on the ELB of the RLN were identified by a comprehensive database search. Relevant data were extracted and pooled into a meta-analysis of the prevalence of branching, branching pattern, distance of ELB point from the larynx, and presence of positive motor signals in anterior and posterior ELB branches. RESULTS: A total of 69 articles (n = 28,387 nerves) from both intraoperative and cadaveric modalities were included in the meta-analysis. The overall pooled prevalence of ELB was 60.0 % (95 % CI 52.0-67.7). Cadaveric and intraoperative subgroups differed with prevalence rates of 73.3 % (95 % CI 61.0-84.0) and 39.2 % (95 % CI 29.0-49.9), respectively. Cadavers most often presented with a ELB pattern of bifurcation, with a prevalence of 61.1 %, followed by no branching at 23.4 %. Branching of the RLN occurred most often at a distance of 1-2 cm (74.8 % of cases) prior to entering the larynx. A positive motor signal was most often noted in anterior RLN branches (99.9 %) but only in 1.5 % of posterior branches. CONCLUSIONS: The anatomy of the RLN is highly variable, and ELB is likely to have been underreported in intraoperative studies. Because of its high likelihood, the possibility of ELB needs to be assessed in patients to prevent iatrogenic injury and long-term postoperative complications.