Modification of the inflammatory profile of mesenchymal stem cells using different culture conditions.

Aim: Mesenchymal stem cells (MSCs) are pluripotent cells with significant therapeutic potential. The objective of this study was to examine the inflammatory profile of MSCs cultured under different conditions. Methods: MSCs were cultured by three strategies: seeding on an extracellular matrix (ECM), spheroids in static culture and spheroids in a bioreactor. Paracrine factors and CD206, a marker of M2 macrophage phenotype, were measured. Results: MSCs grown as spheroids in a bioreactor produced more IL-6 and IL-8 (p < 0.05). Supernatant collected from spheroids under both culture conditions increased the M2 macrophage phenotype almost twofold. Conclusion: Results indicate that the inflammatory profile of the supernatant collected from MSCs can be modified through culture conditions which has impacts for the future of regenerative medicine.

Successful Treatment of Persistent Postcholecystectomy Bile Leak Using Percutaneous Cystic Duct Coiling.

Laparoscopic cholecystectomy is one of the most commonly performed operations worldwide. Cystic duct is the most common site of bile leak after cholecystectomy. The treatment of choice is usually conservative. Using sufficient percutaneous drainage of the biloma cavity and endoscopic retrograde cholangiography (ERCP) with sphincterotomy and/or stenting, the cure rate of bile leaks is greater than 90%. In very rare cases, all of these measures remain unsuccessful. We report a technique for the successful treatment of persistent cystic duct leak. After failed ERCP and stenting, bile leak was treated by coiling the cystic duct through a drain tract. This technique is safe and effective and helps avoid the morbidity of reoperation.

Bariatric aftercare and outcomes in the Medicaid population following sleeve gastrectomy.

BACKGROUND: Medicaid patients tend to have poor access to care and suffer from more obesity and obesity-related co-morbidities compared to their privately insured counterparts. The impact of Medicaid status on outcomes after laparoscopic sleeve gastrectomy (LSG) is unknown. The aim of this study was to identify factors that influence outcomes following LSG in the adult Medicaid population of Louisiana with particular focus on adherence to bariatric aftercare attendance and access to care. METHODS: A retrospective review of 63 Medicaid patients undergoing LSG was performed. Demographic data, access to care, weight, co-morbidities morbidity, and mortality were analyzed. Changes in weight and obesity-related co-morbidities were analyzed for patients with ≥12 months of follow-up. Regression analyses were used for estimating the relationships among variables. RESULTS: The majority of patients were female and non-Caucasian. The mean age was 38.6 years. Morbidity was 16% and mortality was 0%. The average distance traveled to clinic was 71.9 miles. Within the first year only 10% of the patients attended all post-operative clinic visits. A multiple logistic model showed that the only predictor of clinic attendance was increased age. At a mean follow-up of 17.7 months, the mean percent excess body weight loss was 47.2%. Greater pre-surgical weight was the only variable associated with suboptimal weight loss. Improvement or resolution of all major co-morbidities was seen in 65% of patients. CONCLUSION: Medicaid patients had a poor attendance at bariatric surgery follow up appointments. Since long-term follow-up is critical, we needed to develop strategies that will optimize follow-up in this patient population.

Watchful waiting for ventral hernias: a longitudinal study.

Ventral hernias are a common clinical problem. Immediate repair is recommended for most ventral hernias despite significant recurrence rates. This practice may be related to a lack of understanding of the natural history of ventral hernias. The purpose of this study was to determine the natural history of ventral hernias and to determine if watchful waiting is an acceptable and safe option. Forty-one patients with ventral hernias were enrolled in a longitudinal cohort study of watchful waiting. Primary outcomes were functional impairment resulting from hernia disease as measured by the Activities Assessment Scale (AAS) and changes from baseline to two years in the physical and mental component score of the SF-36 Health Survey. Secondary outcomes included complications such as incarceration. Mixed-effects model for repeated measures and Student's t tests were used to evaluate scale performance. The mean age of enrollees was 64 years, and the mean hernia size was 239 cm(2). Eleven patients were lost to follow-up, and seven patients died of other causes. All remaining patients were followed for two years. There was one incarceration during the follow-up period. There was no deterioration in the AAS score (baseline vs 24 months = 28 vs 25, P = 0.60). There was deterioration of the physical functioning dimension of the SF-36 (baseline vs 24 months = 40 vs 32, P < 0.01), but the mental functioning dimension was improved (45 vs 51; P = 0.01). Watchful waiting was a safe option for patients in this study with ventral hernias.

Diabetes mellitus and colorectal cancer prognosis: a meta-analysis.

BACKGROUND: Diabetes mellitus is associated with an increased incidence of colorectal cancer, but the impact of diabetes mellitus on colorectal cancer prognosis is not clear. OBJECTIVE: We conducted a meta-analysis of observational studies to examine the association between preexisting diabetes mellitus and colorectal cancer all-cause mortality, cancer-specific mortality, and recurrence. DATA SOURCES: Medline and Embase were searched through August 22, 2012. STUDY SELECTION: We included studies reporting all-cause mortality, cancer-specific mortality, disease-free survival, or recurrence in patients who have colorectal cancer according to diabetic status. INTERVENTION: Meta-analyses were performed by the use of random-effects models. MAIN OUTCOME MEASURES: The primary outcomes measured were all-cause mortality, cancer-specific mortality, and disease-free survival. RESULTS: Twenty-six articles met our inclusion criteria. Patients with colorectal cancer who had diabetes mellitus had a 17% increased risk of all-cause mortality (relative risk, 1.17; 95% CI, 1.09-1.25) and a 12% increased risk of cancer-specific mortality (relative risk, 1.12; 95% CI, 1.01-1.24) in comparison with those who did not have diabetes mellitus. Those with diabetes mellitus also had poorer disease-free survival (relative risk, 1.54; 95% CI, 1.08-2.18) compared with their nondiabetic counterparts. In subgroup analyses, diabetes mellitus was associated with all-cause mortality in both rectal (relative risk, 1.24; 95% CI, 1.07-1.29) and colon cancer patients (relative risk, 1.17; 95% CI, 1.07-1.29). Sensitivity analyses including only patients with nonmetastatic disease identified stronger associations between diabetes mellitus and both all-cause (relative risk, 1.32; 95% CI, 1.21-1.44) and cancer-specific (relative risk, 1.27; 95% CI, 1.06-1.52) mortality. LIMITATIONS: Some studies had short follow-up or did not report mean or median follow-up. The included studies were heterogeneous in study population, diabetes mellitus diagnostic criteria, and outcome ascertainment. CONCLUSION: Patients with colorectal cancer who have diabetes mellitus are at greater risk for all-cause and cancer-specific mortality and have worse disease-free survival than those who do not have diabetes mellitus. Studies are warranted to determine whether the proper treatment could attenuate the excess mortality among patients with colorectal cancer who have diabetes mellitus.

Doublecortin-like kinase 1 exhibits cancer stem cell-like characteristics in a human colon cancer cell line.

OBJECTIVE: Colon cancer stem cells (CSCs) are implicated in colorectal cancer carcinogenesis, metastasis, and therapeutic resistance. The identification of these cells could help to develop novel therapeutic strategies. Doublecortin-like kinase 1 (DCLK1) has been viewed as a marker for gastrointestinal stem cells that fuel the self-renewal process, however others view them as a marker of Tuft cells or as an enteroendocrine subtype. The purpose of this study was to use a colon cancer cell line to identify and characterize the stem-like characteristics of the DCLK1+ cell population. METHODS: To enrich stem-like cells, HCT116 cells (derived from colon adenocarcinomas) were cultured using serum-free media to form spheres under both normal oxygen and hypoxia condition. DCLK1 transcript expression in the adherent parental cells and spheroids was quantified using quantitative real time reverse transcription- polymerase chain reaction [(q)RT-PCR]. DCLK1 protein expression was determined using flow cytometry. Self-renewal capability from adherent parental cells and spheroids was determined using extreme limiting dilution analysis (ELDA). RESULTS: Under both normal oxygen and hypoxia condition, the adherent parental cells were composed of cells that express low levels of DCLK1. However, spheroids exhibited an increased frequency of cells expressing DCLK1 on both mRNA and protein levels. Cells derived from spheroids also possess stronger self-renewal capability. CONCLUSIONS: The higher fraction of DCLK1+ cells exhibited by spheroids and hypoxia reflects the stem-like characteristics of these cells. DCLK1 may represent an ideal marker to study and develop effective strategies to overcome chemo-resistance and relapse of colon cancer.

Repair of incisional hernias with biological prosthesis: a systematic review of current evidence.

BACKGROUND: No consensus has been reached on the use of bioprosthetics to repair abdominal wall defects. The purpose of this systematic review was to summarize the outcomes from studies describing this use of various bioprosthetics for incisional hernia repair. METHODS: Studies published by October 2011 were identified through literature searches using EMBASE, MEDLINE, and the Cochrane Central Register of Controlled Trials. RESULTS: A total of 491 articles were scanned, 60 met eligibility criteria. Most studies were retrospective case studies. The studies ranged considerably in methodologic quality, with a modified Methodological Index of Nonrandomized Studies score from 5 to 12. Many repairs were performed in contaminated surgical sites (47.9%). At least one complication was seen in 87% of repairs. Major complications noted were wound infections (16.9%) and seroma (12.0%). With a mean follow-up period of 13.6 months the hernia recurrence rate was 15.2%. CONCLUSIONS: There is an insufficient level of high-quality evidence in the literature on the value of bioprosthetics for incisional hernia repair. Randomized controlled trials that use standardized reporting comparing bioprosthetics with synthetic mesh for incisional hernia repair are needed.

Immunolocalization of DCAMKL-1, a putative intestinal stem cell marker, in normal colonic tissue.

Doublecortin and CaM kinase-like-1 (DCAMKL-1) is a microtubule-associated protein kinase which has been recently proposed as a gastrointestinal stem cell marker. The aim of our study was to characterize DCAMKL-1 expression in normal human colon by immunohistochemistry. DCAMKL-1 immunostaining was performed on histologically normal colorectal biopsies from 14 patients. Immunoreactivity was found in over 60% of colonic crypts and was represented by strong cytoplasmic staining, anti-luminal in distribution, and was reminiscent of cytoplasmic orientation of neuroendocrine cells. The highest number (48.5%) of DCAMKL-1 positive cells was found in the first 4 cells from the crypt base. Seventy percent of DCAMKL-1 positive cells were located in the lower third of the crypt, 26% in the middle third and 4% in the upper third. Therefore, in normal colonic mucosa, expression of DCAMKL-1 is not confined to the stem cell compartment. When we compared DCAMKL-1 immunostaining with that of the leucine-rich-repeat-containing G-protein-coupled receptor 5 (Lgr5), an intestinal stem cell marker, and chromogranin-A (CgA), an enteroendocrine cell marker, we found that DCAMKL-1 positive cells co-stained with Lgr5 only at the crypt base, but co-stained with CgA throughout the crypt. Our findings suggest that DCAMKL-1 marks a subset of colorectal stem cells, as well as a subset of enteroendocrine cells.

DCLK1 immunoreactivity in colorectal neoplasia.

INTRODUCTION: Microtubule-associated doublecortin and CaM kinase-like-1 (DCLK1) is a novel candidate marker for intestinal stem cells. The aim of our study was to assess DCLK1 immunoreactivity in colorectal carcinogenesis and its correlation with prognosis. METHODS: DCLK1 immunostaining was performed in colorectal tissue from 71 patients, including 18 adenomatous polyps, 40 primary adenocarcinomas, and 14 metastatic lesions. Each case was evaluated by a combined scoring method based on the intensity of staining (score 0-3) and the percentage of tissue staining positive (score 0-3). Immunoexpression for DCLK1 was considered as positive when the combined score was 2-6 and negative with a score of 0-1. RESULTS: Overall, 14/18 (78%) of polyps, 30/40 (75%) of primary adenocarcinomas, and 7/14 (50%) of distant metastases were positive for DCLK1. In adenomatous polyps and primary cancer there was no association between DCLK1 staining score and tumor pathology. However, after curative colorectal cancer resection, patients whose tumor had a high (≥5) combined staining score had increased cancer-specific mortality compared to patients with low (0-4) staining score (hazard ratio 5.89; 95% confidence interval: 1.22-28.47; P = 0.027). CONCLUSION: We found that DCLK1 is frequently expressed in colorectal neoplasia and may be associated with poor prognosis. Further studies are necessary to validate the use of DCLK1 as a prognostic marker.

Transaxillary gasless robotic thyroidectomy: a single surgeon's experience in North America.

OBJECTIVE: To describe a robotic technique for transaxillary gasless thyroidectomy with the addition of intraoperative peripheral nerve monitoring in the surgical management of thyroid disease. DESIGN: Prospective study. SETTING: Academic institution. PATIENTS: Fifty patients underwent robotic transaxillary thyroidectomy from September 1, 2009, to August 31, 2010. All the patients underwent preoperative and postoperative direct laryngoscopy. The patients' demographic information, operative times, complications, postoperative hospital stay, and the surgeon's learning curve were evaluated. MAIN OUTCOME MEASURES: Feasibility of the robotic approach, patient and gland characteristics, operative time, and complications. RESULTS: Thirty-nine females and 11 males with a mean age of 48.2 (age range, 13-76) years were included in the study. A total of 37 surgical procedures were lobectomies, and 13 were total or near-total thyroidectomies. The mean nodule size (range) was 24.9 (10-72) mm. The mean operative time (range) was 122.5 (81-280) minutes, mean docking time (range) was 10.1 (6-15) minutes, and mean console time (range) was 55.5 (10-140) minutes. Mean blood loss (range) was 25 (10-100) mL. There were no conversions to conventional open surgery. One patient developed transient radial nerve neuropathy that resolved spontaneously. There were no other postoperative complications. In addition, there was no evidence of vocal cord palsy or paresis on postoperative laryngoscopy. All the patients were discharged home within 24 hours. Subjectively, the cosmetic results were considered excellent owing to the hidden anatomical location of the incision site. CONCLUSIONS: We have demonstrated the technique to be feasible, safe, and applicable for patients with thyroid disease. We believe that the use of robotic technology for endoscopic thyroid surgical procedures could overcome the limitations of conventional endoscopic surgical procedures in the surgical management of thyroid disease. To our knowledge, this is the first reported large series using this novel technique in the United States.

Acute acalculous cholecystitis after gastrointestinal surgery.

Acute acalculous cholecystitis has been identified as a rare but potentially devastating entity after trauma, and burns, as well as in critically ill patients, and in the postoperative period. Gastrointestinal surgery is most frequently implicated in postoperative acute acalculous cholecystitis, especially after gastric and colorectal procedures. Review of the English literature identified 28 articles reporting 76 cases of acute acalculous cholecystitis after gastrointestinal operations, which included a case from Tulane University Medical Center of a 64-year-old man who developed postoperative acute acalculous cholecystitis after elective left hemicolectomy. A total of 52.4 per cent of the patients developed gangrenous acute acalculous cholecystitis, with a mortality rate of 21.1 per cent, much higher than that reported in postoperative calculous cholecystitis. This emphasizes the need for a high level of suspicion and early detection in the postoperative period to avoid devastating consequences.

Histologic and biomechanical evaluation of biologic meshes following colonization with Pseudomonas aeruginosa.

BACKGROUND: Biologic meshes have become increasingly popular for the repair of abdominal wall defects, especially in contaminated sites. The purpose of this study was to evaluate the histologic and biomechanical properties of biologic mesh in response to a bacterial encounter. MATERIAL AND METHODS: A rat model of Pseudomonas aeruginosa colonization and infection of subcutaneously implanted biologic mesh was used. Samples of biologic meshes [acellular human dermis (ADM) and porcine small intestine submucosa (SIS)] were inoculated with P. aeruginosa (10(5) or 10(9) cfu) or saline as a control prior to wound closure (n = 6 per group). After 10 or 20 d, the meshes were harvested. The recovered meshes were analyzed for histologic changes and bacterial recovery as well as the material strength properties. Statistical significance (P < 0.05) was determined using 1-way analysis of variance or Mann-Whitney test. RESULTS: ADM and SIS colonized with 10(9) cfu P. aeruginosa showed an increased inflammatory response with an associated decrease in neo-vascularization (P < 0.05) at 20 d post-implantation compared with controls. P. aeruginosa had no effect on the tensile strength of ADM, but the tensile strength and modulus of elasticity were reduced for SIS compared with controls at 20 d. CONCLUSION: Bacterial colonization of ADM and SIS with 10(9)cfu P. aeruginosa negatively effected neovascularization and cellular re-population of the material over time but only SIS showed alterations in their biomechanical properties in response to this gram-negative bacterial challenge.

Effective home laparoscopic simulation training: a preliminary evaluation of an improved training paradigm.

BACKGROUND: Laparoscopic simulation training has proven to be effective in developing skills but requires expensive equipment, is a challenge to integrate into a work-hour restricted surgical residency, and may use nonoptimal practice schedules. The purpose of this study was to evaluate the efficacy of laparoscopic skills training at home using inexpensive trainer boxes. METHODS: Residents (n = 20, postgraduate years 1-5) enrolled in an institutional review board-approved laparoscopic skills training protocol. An instructional video was reviewed, and baseline testing was performed using the fundamentals of laparoscopic surgery (FLS) peg transfer and suturing tasks. Participants were randomized to home training with inexpensive, self-contained trainer boxes or to simulation center training using standard video trainers. Discretionary, goal-directed training of at least 1 hour per week was encouraged. A posttest and retention test were performed. Intragroup and intergroup comparisons as well as the relationship between the suture score and the total training sessions, the time in training, and attempts were studied. RESULTS: Intragroup comparisons showed significant improvement from baseline to the posttest and the retention test. No differences were shown between the groups. The home-trained group practiced more, and the number of sessions correlated with suture retention score (r(2) = .54, P < .039). CONCLUSIONS: Home training results in laparoscopic skill acquisition and retention. Training is performed in a more distributed manner and trends toward improved skill retention.

Motor and sensory branching of the recurrent laryngeal nerve in thyroid surgery.

INTRODUCTION: Recognition of extralaryngeal bifurcation of the recurrent laryngeal nerve (RLN) is crucial, because inadvertent intraoperative division may lead to significant morbidity. The purpose of this study was to examine the incidence of extralaryngeal bifurcation of the RLN and the distance that the initial bifurcation occurs from the cricothyroid insertion site of the RLN. We also sought to demonstrate the location of the RLN branches containing a predominance of motor fibers. METHODS: This prospective study of 220 patients with data on 310 RLNs collected the type of operation, incidence of bifurcation, distance from the cricothyroid insertion point to the point of initial bifurcation, and location of the motor fibers by assessing a stimulus response on the Medtronic NIMS as they relate to the laryngeal muscles. RESULTS: A total of 310 RLNs in 220 patients were studied. There were 133 RLNs (42.9%) that bifurcated before entering the larynx. These bifurcations occurred 51.1% on the right, 48.9% on the left, and 33.3% bilaterally. The median branching distance from the cricothyroid membrane on the right was 6.33 mm, and on the left was 6.37 mm. In all bifurcated RLNs, the motor fibers were located exclusively in the anterior branches. CONCLUSION: Extralaryngeal bifurcation was found in 42.9% of the RLNs in this case series. The motor fibers are located in the anterior branches. Great caution is therefore required after the presumed identification of the RLN to ensure there is no unidentified anterior branch.

Colonic large cell neuroendocrine carcinoma obscured by an initial diagnosis of diverticulitis.

Large cell neuroendocrine carcinomas are rare and aggressive colorectal malignancies that have a dismal prognosis. We present the following case of a patient who presented with signs and symptoms of diverticulitis. After failure of medical management, surgical intervention revealed a poorly differentiated adenocarcinoma with a component of large cell neuroendocrine carcinoma.

Circulation of progenitor cells in obese and lean colorectal cancer patients.

BACKGROUND: Colorectal cancer (CRC) is a common life-threatening malignancy; risk and progression are elevated in obesity. The purpose of this study was to measure the frequency of circulating CD34-positive endothelial and progenitor cells in the circulation and evaluate their potential values as CRC biomarkers. METHODS: Blood was collected from 45 patients with CRC and compared with cancer-free control donors. Detection and enumeration of cells was carried out by flow cytometry on the basis of immunophenotypes established for the cell populations of interest: hematopoietic and endothelial circulating progenitor cells, endothelial cells, mesenchymal stromal cells (MSC), and CD34bright leukocytes (CD34b LC). Groups were compared using multivariate regression analysis. Receiver-operating characteristic (ROC) curve analysis was used to evaluate the diagnostic values. RESULTS: After adjusting for age and body mass index (BMI), the mean frequencies of MSCs and CD34b LCs were significantly higher in the circulation of patients with CRC than in controls. The areas under the ROC curve were 0.77 and 0.82 for MSCs and CD34b LCs, respectively. The frequency of circulating MSCs, but not of the other cell populations, was also found to be significantly higher in the circulation of obese patients with CRC (BMI ≥ 30 kg/m(2)) than in lean patients with CRC and obese controls. CONCLUSIONS: Increased frequency of MSCs and CD34b LCs in the peripheral blood may represent a new diagnostic marker for CRC. IMPACT: BMI-dependent changes in circulating MSCs, potentially mobilized from white adipose tissue may reveal their trafficking to tumors, which could be one of the mechanistic links between obesity and cancer progression.

The effect of bacterial infection on the biomechanical properties of biological mesh in a rat model.

BACKGROUND: The use of biologic mesh to repair abdominal wall defects in contaminated surgical fields is becoming the standard of practice. However, failure rates and infections of these materials persist clinically. The purpose of this study was to determine the mechanical properties of biologic mesh in response to a bacterial encounter. METHODS: A rat model of Staphylococcus aureus colonization and infection of subcutaneously implanted biologic mesh was used. Samples of biologic meshes (acellular human dermis (ADM) and porcine small intestine submucosa (SIS)) were inoculated with various concentrations of methicillin-resistant Staphylococcus aureus [10(5), 10(9) colony-forming units] or saline (control) prior to wound closure (n = 6 per group). After 10 or 20 days, meshes were explanted, and cultured for bacteria. Histological changes and bacterial recovery together with biomechanical properties were assessed. Data were compared using a 1-way ANOVA or a Mann-Whitney test, with p<0.05. RESULTS: The overall rate of staphylococcal mesh colonization was 81% and was comparable in the ADM and SIS groups. Initially (day 0) both biologic meshes had similar biomechanical properties. However after implantation, the SIS control material was significantly weaker than ADM at 20 days (p = 0.03), but their corresponding modulus of elasticity were similar at this time point (p>0.05). After inoculation with MRSA, a time, dose and material dependent decrease in the ultimate tensile strength and modulus of elasticity of SIS and ADM were noted compared to control values. CONCLUSION: The biomechanical properties of biologic mesh significantly decline after colonization with MRSA. Surgeons selecting a repair material should be aware of its biomechanical fate relative to other biologic materials when placed in a contaminated environment.

Clinical significance of magnetic resonance imaging findings in rectal cancer.

Staging of rectal cancer is essential to help guide clinicians to decide upon the correct type of surgery and determine whether or not neoadjuvant therapy is indicated. Magnetic resonance imaging (MRI) is currently one of the most accurate modalities on which to base treatment decisions for patients with rectal cancer. MRI can accurately detect the mesorectal fascia, assess the invasion of the mesorectum or surrounding organs and predict the circumferential resection margin. Although nodal disease remains a difficult radiological diagnosis, new lymphographic agents and diffusion weighted imaging may allow identification of metastatic nodes by criteria other then size. In light of this, we have reviewed the literature on the accuracy of specific MRI findings for staging the local extent of primary rectal cancer. The aim of this review is to establish a correlation between MRI findings, prognosis, and available treatment options.

Recurrent laryngeal nerve: significance of the anterior extralaryngeal branch.

INTRODUCTION: Recognition of extralaryngeal branching of the recurrent laryngeal nerve (RLN) is crucial, because inadvertent operative division may lead to significant postoperative morbidity. The purpose of this study was to examine the incidence of extralaryngeal bifurcation of the RLN and to demonstrate the location of the motor fibers within the branches of the RLN. METHODS: Prospective study on 99 patients over 1 year with operative data collected on the branching of a total of 137 RLNs. Operative data obtained included the type of operation, incidence of nerve bifurcation, the distance from the inferior border of the cricothyroid to the point of bifurcation, and the location of the motor fibers to the intrinsic muscles of the larynx within the branches of the RLN. RESULTS: The RLN was seen intra-operatively in all patients. A total of 137 (right 69, left 68) RLNs in 99 patients undergoing thyroidectomy (total 29; hemi 51), parathyroidectomy (16) and central lymph node dissection (3) were studied. Overall, 46 RLNs (34%) bifurcated prior to entry into the larynx. These bifurcations occurred on the right in 27 (59%) and left 19 (41%). Bilateral bifurcation occurred in 12 (27%) of the 44 patients who underwent bilateral dissections. The median branching distance from the cricothyroid membrane on the right was 8.3 ± 2.5 mm, and on the left was 7.5 ± 1.8 mm. In all bifurcated RLNs, the motor fibers to the vocal cords were located exclusively in the anterior branches. CONCLUSION: Extralaryngeal bifurcation was found in 34% of the RLNs in this case series. The motor fibers of RLN are located in the anterior branch while the posterior branch is only sensory in function. Great caution is, therefore, required after the presumed identification of the RLN to ensure there is no unidentified anterior branch. Identification of the anterior branch may lead to decreased risk of postoperative nerve injury.