External Auditory Canal: Computed Tomography Analysis and Classification

Abstract Introduction Computed tomography (CT) details of the external auditory canal (EAC) are not fully covered in the literature, so building up base for the CT evaluation and description is important. Preoperative details of the EAC are mandatory before any approach or procedure involving the canal. Objective To determine the different dimensions, measurements, and grading of the EAC by CT scan that were not previously published. Methods The CTscans of 100 temporal bones (200 sides) were included. Axial images were acquired with multiplanar reformates to obtain delicate details in coronal and sagittal planes for all subjects. Results At the EAC entry, the mean vertical length (height) was 7.75 ± 1 mm, and its mean horizontal length (width) was 6.1 ±0.8. At the bony cartilaginous junction of the EAC, the mean vertical length was 7.88 ±1 mm, and its mean horizontal length was 6.22 ± 0.9. At the EAC isthmus, the mean vertical length was 6.8 ± 0.97 mm, and its mean horizontal length was 5.2 ± 0.76. At the medial end of the EAC, the mean vertical length was 7.1 ±0.9 mm, and its mean horizontal length was 5.4 ± 0.85. There were no reported significant differences between right and left sides in all dimensions. Males showed significantly longer vertical and horizontal dimensions of the EAC entry, vertical dimension of the isthmus, and vertical dimension of the medial end of the EAC than females. Conclusion This study improves otologists and radiologists' awareness of EAC variations in the ear field and can be of help to residents in training.

A new species of Characidium (Characiformes: Crenuchidae) from the rio Doce basin, Brazil

A new species of Characidium is described from the tributaries of the upper and middle rio Doce basin, Minas Gerais, Brazil. The new species is distinguished from most congeners, except C. cricarense, C. hasemani, C. helmeri, C. kalunga, C. pterostictum, C. schubarti, C. summus, and C. travassosi by lacking scales in the area between the anterior limit of the isthmus and the anterior margin of cleithrum. The new species differs from the aforementioned species by a series of characters, including the presence of the adipose fin, 2­-4 scales between the anus and anal fin, two rows of dentary teeth, presence of the parietal branch of the supraorbital canal, 4 scale rows above the lateral line, and absence of two conspicuous inclined dark bands on each caudal-fin lobe. The new species further differs from most congeners with an unscaled ventral surface of the isthmus by the presence of 33-34 pored scales on the lateral line and by the dark dashes on the caudal fin-rays not forming well-defined bands.(AU)

Uma nova espécie de Characidium é descrita de afluentes do alto e médio curso da bacia do rio Doce, Minas Gerais, Brasil. A nova espécie se distingue da maioria das congêneres, exceto C. cricarense, C. hasemani, C. helmeri, C. kalunga, C. pterostictum, C. schubarti, C. summus e C. travassosi pela falta de escamas na área entre o limite anterior do istmo e a margem anterior do cleitro. A nova espécie difere das espécies acima mencionadas por uma série de caracteres, incluindo a presença de nadadeira adiposa, 2-4 escamas entre o ânus e a nadadeira anal, duas séries de dentes no dentário, ramo parietal do canal supraorbital presente, 4 séries de escamas acima da linha lateral e ausência de duas bandas escuras inclinadas em cada lobo da nadadeira caudal. A nova espécie difere ainda mais da maioria das congêneres com superfície ventral sem escamas no istmo por ter 33-34 escamas perfuradas na linha lateral e traços escuros nos raios da nadadeira caudal não formando bandas bem definidas.(AU)

Capacidad de Penetración y Difusión de la Medicación, Intraconducto en Túbulos Dentinales, Conductos Laterales e Istmos. Una Revisión Sistemática

RESUMEN: El objetivo de la terapia endodóntica consiste en tratar o prevenir la periodontitis apical. La efectiva eliminación o disminución de microbiota es esencial para la reparación periapical. Debido a esto, se utiliza el empleo de medicamentos intraconductos para tratar químicamente el sistema de conductos radiculares, y cobra relevancia la capacidad de penetración y difusión de dicho medicamento para entrar en contacto directo con los microorganismos que penetren dentro de los túbulos dentinales, conductos laterales e itsmos. Se realizó una revisión de la literatura en bases de datos electrónicas con los buscadores "Pubmed, Scielo y Google Académico", utilizando palabras clave para identificar la literatura publicada relevante en inglés. El análisis y los criterios de elegibilidad se documentaron de acuerdo con los elementos de informe para revisiones sistemáticas y meta-análisis (Preferred Reporting Items for Systematic Reviews and Meta-Analysis, PRISMA). No se impusieron restricciones sobre la fecha de publicación. Se recogieron datos sobre capacidad de difusión de medicación intraconductos en túbulos dentinales, conductos laterales e itsmos radiculares y se sometieron a análisis descriptivo de datos. La búsqueda bibliográfica en bases de datos electrónicas según los criterios de inclusión arrojó 45 títulos y resúmenes. Entre ellos, 7 artículos fueron seleccionados. Se determinó un rango de penetración del medicamento muy variable, entre 27,7 - 2350 μm y rango de difusión de 200-500 μm. Hay pocos estudios publicados que reporten la capacidad de penetración y difusión de la medicación intraconductos. El vehículo empleado y diámetro de las partículas en la preparación del medicamento y la eliminación de la capa de desecho aumentaría la capacidad de penetración/difusión del medicamento intraconductos dentro del túbulo dentinal, conductos laterales e itsmo.

ABSTRACT: The objective of endodontic therapy is to treat or prevent apical periodontitis. The effective elimination or reduction of the microbiota is essential for periapical repair. Due to this, the use of intracanal drugs is used to chemically treat the root canal system, and the penetration and diffusion capacity of said drug becomes relevant to come into direct contact with the microorganisms that penetrate inside the dentinal tubules, lateral canals and isthmus. A literature review was carried out in electronic databases with the search engines "Pubmed, Scielo and Google Academic", using keywords to identify the relevant published literature in English. The analysis and eligibility criteria were documented according to the reporting items for systematic reviews and meta-analyzes (Preferred Reporting Items for Systematic Reviews and Meta-Analysis, PRISMA). No restrictions were placed on the date of publication. Data on intracanal drug diffusion capacity in dentinal tubules, lateral canals and root isthmus were collected and subjected to descriptive data analysis. The bibliographic search in electronic databases according to the inclusion criteria yielded 45 titles and abstracts. Among them, 7 articles were selected. A highly variable drug penetration range was determined, between 27.7 - 2350 μm and a diffusion range of 200-500 μm. There are few published studies that report the penetration and diffusion capacity of intracanal medication. The vehicle used and the diameter of the particles in the preparation of the drug and the elimination of the waste layer would increase the penetration / diffusion capacity of the drug within the dentinal tubule, lateral canals and isthmus.

Are clinicopathological features of the isthmic thyroid nodule different from nodules in thyroid lobes? A single center experience

ABSTRACT Objectives: Thyroid nodules located in isthmus were found less prevalent, although papillary thyroid cancer in this location was reported to be more aggressive behaviour in some studies. Our aim was to evaluate hormonal,ultrasonographic, and cytopathologic features of nodules located in isthmus (isthmic nodules). Subjects and methods: Patients who underwent thyroidectomy between 2006-2014 reviewed retrospectively. Hormonal, ultrasonographic, and cytopathologic features compared between patients with isthmic (Group-1) and with lober (non-isthmic, Group-2) nodules. Results: Group-1 and Group-2 consisted of 251 and 2076 patients, respectively. 260 isthmic (5.5%) and 4433 non-isthmic (94.5%) nodules were compared.However,most ultrasonographical features such as presence of microcalcification and halo, diameters, echogenicity, texture, margin, and vascularity were similar between groups, macrocalcification rate was lower in isthmic nodules (18.8%, 25.9%; p = 0.012). Cytologic results were also similar.Although malignancy rate was lower in isthmic nodules (6.2%, 12.5%; p = 0.002), type of thyroid cancer was similar in isthmic and non-isthmic nodules.When malignant isthmic (n = 16,2.8%) and malignant non-isthmic nodules (n = 553, 97.2%) were compared, diameter and type of tumor, lymphovascular and capsular invasions, extrathyroidal extension and multifocality rates were not statistically significant.Malignant isthmic nodules (n = 16, 6.2%) had smaller size [10.1 (7.5-34.5) mm, 19.95 (8.4-74.1) mm; p = 0.002], and higher hypoechogenicity rate (31.3%, 5.7%, p = 0.003) compared to benign isthmic nodules (n = 244, 93.8%). Negative predictive value was higher and positive predictive value was lower in isthmic nodules compared to non-isthmic nodules (p = 0.033, p = 0.047, respectively). Conclusion: Isthmic nodules appear to be indolent because of having lower malignancy rate. FNAB might be required in isthmic nodules even if it has relatively small size.The surgery with limited extent or follow-up might seem to be reliable in the management of patients having isthmic nodules especially with indeterminate cytology.

Patterns of central lymph node metastasis of the cN0 papillary thyroid carcinoma located in the isthmus and their significance to the choice of operative method and scope / 中华内分泌外科杂志

Objective:To investigate the patterns and risk factors of central lymph node metastasis in node-negative neck (cN0) papillary thyroid carcinoma located in the isthmus. To discuss different operation methods and the postoperative complications to find out the appropriate surgical approach and scope.Methods:Forty-eight patients with cN0 papillary thyroid carcinoma located in isthmus for surgery at the First Hospital of Chongqing Medical University from Jan. 2013 to Dec. 2019 were reviewed retrospectively. They were divided into two groups: the lymph node metastatic group and the lymph node non-metastatic group. The metastatic lymph node group was further divided into the group with the number of lymph node metastasis ≤5 and the lymph node metastasis > 5. The clinical features, including gender, age, number and size of tumor, extrathyroidal extension, and whether combined with Hashimoto’s thyroiditis, the incidence of central lymph node metastasis and related factors, the scope of surgery, postoperative complications and recurrence were analyzed. SPSS 21.0 statistical software was used for statistical analysis, t test was used for measurement data, and χ2 test was used for counting data. Results:Among 48 patients, 27 had lymph node metastasis, with a metastatic rate of 56.25% (27/48) . Lymph node metastasis in pretracheal, prelaryngeal, left and right paratracheal lymph node was present in 47.9%, 22.9%, 20.8% and 16.7% of the patients respectively. The proportion and risk of lymph node metastasis were significantly increased in patients with tumor size>1 cm ( P=0.014, OR=6.78, 95% CI:1.59-28.95) . In patients with the number of lymph node metastasis > 5, the incidence of tumor size > 1 cm, prelaryngeal, left and right paratracheal lymph node metastasis was significantly higher than that of patients with lymph node metastasis ≤5 ( P=0.008, P=0.033, P=0.025, P=0.027) . There was a higher proportion of pretracheal or prelaryngeal lymph node metastasis in patients with left paratracheal lymph node metastasis ( ( P=0.008, P=0.007) . Multivariate analyses of risk factors associated with paratracheal lymph node metastasis indicated that the paratracheal lymph node metastasis correlated with the metastasis of pretracheal and (or) prelaryngeal lymph node ( P=0.016, OR=5.92, 95% CI:1.39-25.3) . In 48 patients with cN0 isthmic PTC, 43 cases underwent total thyroidectomy plus bilateral central lymph node dissection, and 5 patients reseived extended isthmus resection plus prelaryngeal and pretracheal lymph node dissection. 21 (41.8%) patients in total thyroidectomy group had PTH reduction, which was a transient hypoparathyroidism. 48 patients were followed up for 1-6 years without recurrence or metastasis. Conclusions:cN0 isthmic papillary thyroid carcinoma has a high incidence of central lymph node metastasis. Pretracheal and prelaryngeal lymph node are the most common metastatic location. For patients with tumor size>1 cm, a total thyroidectomy plus bilateral prophylactic central lymphadenectomy is needed. However, for patients without capsular invasion, tumor size≤1 cm, without pretracheal and prelaryngeal lymph node metastasis confirmed by intraoperative fast-frozen pathology, extended isthmus resection plus prophylactic pretracheal and prelaryngeal lymphadenectomy can be selected for reducing the complications of operation.

Clinicopathological characteristics and risk factors of lymph node metastasis in isthmus papillary thyroid microcarcinoma / 中华内分泌外科杂志

Objective:To investigate the clinicopathological characteristics of papillary thyroid microcarcinoma in the isthmus (PTMCI) and the independent risk factors of central lymph node metastasis.Methods:58 consecutive patients with PTMCI admitted from Jan. 2016 to Dec. 2018 (isthmus group) were retrospectively analyzed, including 15 males and 43 females,age (42.93±12.69) years old; According to the specific location of papillary thyroid microcarcinoma (PTMC) in isthmus, PTMCI were subdivided into the right PTMCI and the left PT-MCI 67 patients with a single PTMC located in the unilateral lobe were randomly selected as a control (lobe group) , including 13 cases of male and 54 cases of female, age (47.18±11.34) years old. Index included the patient’s age, gender, tumor diameter, TPOAb, aspect ratio, microcalcification, capsular invasion, lymph node metastasis, surgical methods, operation method, and scope of lymph node dissection. SPSS 21.0 software was used for statistical analysis. The quantitative data of normal distribution was expressed as ± s,and the difference between the two groups was compared by chi-square test.The risk factors of CLNM of the isthmus group were analyzed with univariate chi-square test and multivariate Logistic regression analysis.The difference was statistically significant if P<0.05. Results:Compared with PTMC, PTMCI showed a higher rate of capsule invasion ( P=0.003) ,lymph node metastasis ( P=0.049) ,lymph node metastasis in central region ( P=0.033) ,and surgical methods between the two groups were statistically significant ( P<0.05) ;But PTMCI was significantly lower than PTMC in aspect ratio>1 ( P<0.05) . Univariate analysis showed that capsule invasion ( P=0.001) and microcalcification ( P=0.012) were risk factors for PTMCI lymph node metastasis. Multivariate Logistic regression analysis showed that capsule invasion ( P=0.016) and microcalcification ( P=0.046) were independent risk factors for central lymph node metastasis in PTMCI. Conclusions:Compared with PTMC,PTMCI indicates a higher rate of capsular invasion,lymph node metastasis in prelaryngeal and central lymph node;Compared with PTMC, PTMCI indicates a lower rate of aspect ratio>1; Capsule invasion and microcalcification are independent risk factors for central lymph node metastasis in PTMCI. For patients with the right PTMCI or the left PTMCI and also without capsular invasion and calcification,ipsilateral central lymph node dissection should be considered.

Location, incidence and clinical implications of the root canal isthmus / 口腔疾病防治

@#Root canal isthmus(RCI) is defined as a narrow, ribbon-shaped communication between two root canals that contains pulp or tissue derived from pulp. Any root that contains two or more root canals has the potential to contain an isthmus. The incidence of RCI from different tooth positions varies, with the highest RCI incidences usually found in the mesial root of the mandibular first molar and the mesiobuccal root of the maxillary first molar. The presence of RCI increases the difficulty of root canal therapy and introduces uncertainty regarding the prognosis for dental treatment. It is recommended to use CBCT and dental microscopy to identify teeth with suspected RCI in clinical practice. At the same time, for treatment of teeth with RCI, appropriate instruments should be selected, and enhanced root canal irrigation assisted by ultrasound should be considered to improve the success rate of root canal treatment and endodontic root-end surgery. The current technology still has some limitations regarding the cleaning and filling of RCI and additional research and development. Improvement of the corresponding technology and equipment is a current research hotspot and a future research direction.

Isthmus agenesis with variant topography of levator glandulae thyroideae: A case report

The thyroid gland is an imperative endocrine gland present in the neck known commonly for its morphological variations. During routine dissection agenesis of the isthmus of the thyroid gland was observed with levator glandulae thyroidea extending from both the lateral lobes with stout stalks of pyramidal lobes bilaterally. The Levator glandulae thyroidea is a fibro-musculo-glandular band. usually, present unilaterally or extending from isthmus connecting the pyramidal lobe of the thyroid gland to the hyoid bone. The site of the isthmus is often associated with anastomosis of vessels supplying thyroid gland but strikingly no such anastomosis was observed. The presence of such variant of levator glandulae thyroidea with agenesis of the isthmus is a rare finding and knowledge of such topographical anatomical variations is crucial for understanding associated pathologies related to the thyroid gland and modus operandi in their management.

Risco de Fibrilação Atrial após Ablação de Flutter Dependente de Istmo Cavo-Tricuspídeo: Vale a Pena Fazer a Ablação da FA Simultaneamente? / Risk of Atrial Fibrillation after Ablation of Cavotricuspid Isthmus-Dependent Atrial Flutter: Is Combined Ablation of Atrial Fibrillation Worthwhile?

Resumo Fundamento A ablação da fibrilação atrial (FA) e do flutter atrial dependente de istmo cavo-tricuspídeo (FLA-ICT) pode ser realizada simultaneamente quando as duas arritmias tenham sido registradas antes do procedimento. Entretanto, a melhor abordagem não é clara quando pacientes com FLA-ICT são encaminhados para ablação sem o registro prévio de FA. Objetivos Avaliar a prevalência e identificar os preditores de ocorrência do primeiro episódio de FA após ablação de FLA-ICT em pacientes sem o registro prévio de FA. Métodos Coorte retrospectiva de pacientes submetidos exclusivamente a ablação por cateter para FLA-ICT, sem registro prévio de FA. As características clínicas foram comparadas entre os grupos em que houve ocorrência de FA pós-ablação de FLA-ICT vs. sem ocorrência de FA. O nível de significância estatística adotado foi de 5%. Na análise de preditores, o desfecho primário avaliado foi ocorrência de FA após ablação de FLA-ICT. Resultados De um total de 227 pacientes submetidos a ablação de FLA-ICT (110 com registro de FA e 33 sem seguimento adequado), 84 pacientes foram incluídos, dos quais 45 (53,6%) apresentaram FA pós-ablação. Não houve variáveis preditoras de ocorrência de FA. Os escores HATCH e CHA2DS2-VASC foram semelhantes nos dois grupos. As taxas de recorrência de FLA-ICT e complicações após a ablação foram de 11,5% e 1,2%, respectivamente. Conclusões A ablação de FLA-ICT é eficaz e segura, mas 50% dos pacientes desenvolvem FA após ablação. Entretanto, ainda é incerto o papel da ablação combinada (FLA-ICT e FA) visando prevenção da ocorrência de FA. (Arq Bras Cardiol. 2020; [online].ahead print, PP.0-0)

Abstract Background Simultaneous ablation of atrial fibrillation (AF) and cavotricuspid isthmus (CTI)-dependent atrial flutter can be performed when both arrythmias had been recorded before the procedure. However, the best approach has not been defined in case of patients referred for ablation with CTI-dependent atrial flutter, without history of AF. Objectives To assess the prevalence and to identify predictors of the first episode of AF after ablation of CTI-dependent atrial flutter in patients without history of AF. Methods Retrospective cohort of patients with CTI-dependent atrial flutter without history of AF undergoing catheter ablation. Clinical characteristics were compared between patients who developed AF and those who did not have AF after the procedure. Significance level was set at 5%. In the analysis of predicting factors, the primary outcome was occurrence of AF after CTI-dependent atrial flutter ablation. Results Of a total of 227 patients undergoing ablation of CTI-dependent atrial flutter (110 with history of AF and 33 without adequate follow-up), 84 were included, and 45 (53.6%) developed post-ablation AF. The HATCH and CHA2DS2-VASC scores were not different between the groups. Recurrence rate of CTI-dependent atrial flutter and complication rate were 11.5% and 1.2%, respectively, after ablation. Conclusions Although ablation of CTI-dependent atrial flutter is a safe and effective procedure, 50% of the patients developed AF after the procedure. However, the role of combined ablation (CTI-dependent atrial flutter plus AF) aiming at preventing AF is still uncertain. (Arq Bras Cardiol. 2020; [online].ahead print, PP.0-0)

Aortic isthmus doppler velocimetry in fetuses with intrauterine growth restriction: A literature review / Dopplervelocimetria do istmo aórtico em fetos com crescimento intrauterino restrito: Uma revisão da literatura

Abstract Intrauterine growth restriction (IUGR) is associated with poor perinatal prognosis and a higher risk of stillbirth, neonatal death, and cerebral palsy. Its detection and the evaluation of its severity by new Doppler velocimetric parameters, such as aortic isthmus (AoI), are of great relevance for obstetrical practice. The AoI is a vascular segment that represents a point of communication between the right and left fetal circulations. It is considered to be a functional arterial shunt that reflects the relationship between the systemic and cerebral impedances, and has recently been proposed as a tool to detect the status of hemodynamic balance and prognosis of IUGR in fetuses. In the present review, we noticed that in healthy fetuses, the AoI net flow is always antegrade, but in fetuses with IUGR the deterioration of placental function leads to progressive reduction in its flow until it becomes mostly retrograde; this point is associated with a drastic reduction in oxygen delivery to the brain. The more impaired the AoI flow is, the greater is the risk of impairment in the Doppler velocimetry of other vessels; and the alterations of the AoI Doppler seem to precede other indicators of severe hypoxemia. Although there seems to be an association between the presence of retrograde flow in the AoI and the risk of long-term neurologic disability, its role in the prediction of perinatal morbi-mortality remains unclear. The AoI Doppler seems to be a promising tool in the management of fetuses with IUGR, but more studies are needed to investigate its employment in clinical practice.

Resumo O crescimento intrauterino restrito (CIUR) está associado a um prognóstico perinatal adverso, com maior risco de óbito intrauterino e neonatal, bem como de paralisia cerebral. Assim, sua detecção e a determinação de sua gravidade por novos parâmetros Dopplervelocimétricos, como o istmo aórtico (IAo), são de fundamental importância na prática obstétrica. O IAo é um segmento vascular que representa um ponto de comunicação entre os sistemas circulatórios fetais esquerdo e direito. É considerado um shunt arterial funcional, capaz de refletir a relação entre as impedâncias dos circuitos cerebral e sistêmico, e foi proposto como uma ferramenta para detecção do status do equilíbrio hemodinâmico e do prognóstico de fetos com CIUR. Na presente revisão, observou-se que, em fetos saudáveis, o fluxo predominante no IAo é sempre anterógrado; mas em fetos com CIUR a deterioração do estágio de insuficiência placentária acarreta reduções progressivas no fluxo ístmico até este apresentar sentido predominantemente retrógrado e levar a uma drástica redução no aporte de oxigênio ao sistema nervoso central. Quanto mais alterado estiver o fluxo no IAo, maior a chance de haver alteração na Dopplervelocimetria de outros vasos; e as alterações no Doppler do IAo parecem preceder outros indicadores de hipoxemia severa. Embora o fluxo retrógrado no IAo pareça se correlacionar com maior risco de alteração no desenvolvimento neurológico a longo prazo, ainda não está claro o seu papel na predição de morbimortalidade perinatal. O Doppler do IAo parece ser um parâmetro promissor no manejo do CIUR; entretanto, mais estudos são necessários para avaliar seu emprego na prática clínica.

Cerebroplacental ratio and aortic isthmus systolic index in evaluation on pregnancy outcome of late-onset fetal growth restriction / 中国介入影像与治疗学

Objective: To explore the value of cerebroplacental ratio (CPR) and aortic isthmus systolic index (ISI) in evaluation on pregnancy outcome of late-onset fetal growth restriction (FGR). Methods: Totally 88 pregnant women with clinically confirmed late-onset FGR were retrospectively analyzed, among them 39 had poor pregnancy outcomes (case group) and 49 had good pregnancy outcomes (control group). CPR and ISI of fetuses were compared between 2 groups. ROC curve was used to analyze the value of CPR and ISI in predicting fetal pregnancy outcomes. Results: CPR and ISI of case group were lower than those of control group (both P<0.01). ROC curve results showed that taken 1.25 as the cut-off value of CPR, the sensitivity and specificity of adverse pregnancy outcome was 82.1% and 59.7%, respectively, and AUC was 0.814; while taken -0.44 as the cut-off value of CPR, the sensitivity, specificity and AUC was 94.9%, 82.7% and 0.930, respectively. Conclusion: Both CPR and ISI had predictive value for fetal adverse pregnancy outcome of late-onset FGR, and ISI was superior to CPR.

Study of root canal isthmus dentin structure and mineral content and microhardness / 口腔疾病防治

Objective@#To investigate the differences in dentin structure, mineral content and microhardness of single premolar roots with or without an isthmus.@*Methods @#Thirty single-root premolars with a canal isthmus (experimental group) and thirty single-root premolars without a canal isthmus (control group) were collected and analyzed by scanning electron microscopy, X-ray energy spectrometry and a Vickers microhardness tester. Structure, mineral content and microhardness were compared. Results In the experimental group, the dentinal tubules were not obvious, and the structure was disordered. In the control group, the dentin tubules of the root canal wall were arranged regularly, and the lumen opening was clear. The Ca and P contents and Ca/P ratio of the experimental group were lower than those of the control group (P < 0.05). The microhardness of the experimental group was less than that of the control group (P < 0.05).@* Results@# In the experimental group, the dentinal tubules were not obvious, and the structure was disordered. In the control group, the dentin tubules of the root canal wall were arranged regularly, and the lumen opening was clear. The Ca and P contents and Ca/P ratio of the experimental group were lower than those of the control group (P < 0.05). The microhardness of the experimental group was less than that of the control group (P < 0.05).@*Conclusion@#The dentin structure of the root canal isthmus was changed, and the Ca, P contents and microhardness were low. The root canal isthmus was a weak link in the root, which could weaken the resistance of the hard tissue of the root tooth, which may be one of the important factors that could cause vertical root fracture.

A Study Of The Variations In The Morphology Of The Thyroid Gland And Its Surgical Correlations

Introduction: Being a highly vascular and one of the essential endocrine glands, the knowledge of the variationsin the morphology of the thyroid gland stands an important role with respect to their identification, isolation orpreservation, and prevention of any untoward complication during the surgeries around the neck region, thusincreasing the chances of favourable surgical outcome.Aim: The aim of the present study was to identify the frequent variants in the structure of the thyroid gland, andto compare the same with the work of other authors.Materials and Methods: The present study was conducted on total 86 thyroid glands with morphological variations,out of which 42 were of males and 44 were of females. These were obtained during routine dissection of the neckin the adult human cadavers aged above 50 years.Results: The most common variation in the present study was the presence of pyramidal lobe (50% in males and65.9% in females), followed by the levator glandulae thyroidae (45.2% in males and 52.3% in females), absenceof the isthmus (7.1% in males and 20.5% in females), accessory thyroid tissue (2.4% in males and 2.8% infemales), and the least common was presence of groove in the thyroid tissue (0% in males and 2.8% in females).There were also combination of variants in some thyroids.Conclusion: The study emphasizes on the common anatomical variations in the thyroid gland morphology andtheir surgical correlations.

Morphological Variations of the Thyroid Gland in the North Indians: A Cadaveric Study with its Clinical Relevance

Introduction: The morphological variations of the thyroid gland are not an uncommon phenomenon and may due to embryological remnant or non-specific development of different parts of it. Prior anatomical knowledge of these variations is of immense importance to prevent catastrophies during or after thyroid surgeries. Therefore, in this study we aimed to investigate the prevalence of morphological variations of the thyroid glands in north Indian cadavers. Subjects and Methods: This study was conducted on 50 formalin embalmed adult human cadavers aging between 40–65 years, of which 40 were males and 10 were females. Thyroid glands were dissected and examined properly for the presence of pyramidal lobe, levator glandulae thyroidae, accessory thyroid tissue and complete absence of isthmus. Results: The pyramidal lobe was present in 9 (18%) and frequently arising from the right side of the isthmus. LGT was found in 7 (14%) and almost in all cases it was extending from the apex of the pyramidal lobe to the hyoid bone. Only 2 (4%) cadavers did not show an isthmus while accessory thyroid tissue was found only in one case. Morphological variations were more common in females than in males and the difference was statistically significant (p value<0.05). The means of all measured parameters were higher in female than in male but these gender differences were not significant (p>0.05). Conclusion: Morphological variation of the thyroid gland is a common phenomenon, particularly in female. Hence it requires proper detection and documentation prior to any thyroid surgery, so that iatrogenic catastrophies can be avoided

A Morphometric Study Of The Thyroid Gland In Human Cadavers

Introduction: The size and shape of the thyroid gland may alter remarkably with age, gender, physiologicalcondition, race, and geographical location. Thus the knowledge of the various parameters and position ofthyroid gland are important while doing surgeries on thyroid gland as well as during tracheostomy in emergencycondition.Materials and methods: The study was structured to investigate the morphometric as well as topographicalfeatures of the thyroid gland in 100 cadavers (58 males and 42 females) from Maharashtrian populationResult: The right lobe of the thyroid gland was found to be larger than the left lobe. An average length and widthof isthmus were 1.38 cm and 1.02 cm. An average weight of thyroid gland was 14.5grams. The P value was 0.00it shows that gender wise difference in different parameters was highly significant. Most commonly the isthmuswas lying opposite to 1st 2nd and 3rd tracheal rings. Gender wise difference in position of isthmus was statisticallyinsignificant.Conclusion: This study highlights the various parameters of thyroid gland as well as shows the gender wisedifference in it.

Agenesis Of Isthmus Of Thyroid Gland – A Rare Case Report In An Adult Male Cadaver

Introduction: The thyroid gland is a highly vascular endocrine gland. The congenital anomalies of thyroid glandincludes thyroglossal cyst, ectopic thyroid tissue and rarely agenesis of one of the lobes or isthmus of thyroidgland. One such rare finding observed in the present study which is highly relevant both to the non – operativeclinician and in operative surgery.Materials and Methods: During routine dissection on an adult male cadaver in the department of anatomy,Ponnaiyah Ramajayam Institute of medical sciences, Chennai, we report agenesis of isthmus of thyroid gland.Results and Discussion: The lobes of the thyroid gland appear to be normal in size, shape and position. Anotherimportant rare finding was the presence of levator glandulae thyroideae which arises from the left lobe to thehyoid bone. Agenesis of isthmus and presence of levator glandulae thyroideae from the left lobe might occur dueto high separation of thyroglossal duct.Conclusion: The knowledge of normal anatomy and its variation of this vital endocrine gland is highly essentialfor physicians and surgeons for the repair of any thyroid ailment and also during tracheostomy

Minimally Invasive Horizontal Intercartilaginous Incision during Tracheostomy – A Cadaveric Study / 체질인류학회지

The paper describes a minimally invasive tracheostomy technique that uses an intercartilaginous incision without resection of the tracheal cartilage and discusses its feasibility. A total of 20 adult cadavers (13 males and 7 females) were included in this study. The distance from the arch of the cricoid cartilage to the thyroid isthmus, maximal displacement of the thyroid isthmus, number of tracheal rings underneath the thyroid isthmus, and maximally opened distance resulting from an intercartilaginous incision were measured. The mean distance from the arch of the cricoid cartilage to the thyroid isthmus was 21.4±5.0 mm. The thyroid isthmus mainly overlaid the 3rd and 4th tracheal rings. The mean maximal displacement of the thyroid isthmus was 9.0±2.8 mm. Minimally invasive tracheostomy via an intercartilaginous incision is a feasible technique. A skin incision 2 cm below the cricoid cartilage enables exposure of the thyroid isthmus and anular ligament between the 2nd and 3rd tracheal rings. The intercartilaginous incision allows sufficient space for the tracheostomy tube. An intercartilaginous incision without resection of a tracheal ring can be a good alternative tracheostomy technique, especially for patients who require transient tracheostomy.

Research progresses of hemodynamics in aortic isthmus of fetuses during the second and third trimester / 中国医学影像技术

The aortic isthmus (AOI) connects the blood circulation of fetal supraphrenic and subphrenic organs,reflecting fetal blood distribution directly and quickly.The waveform of AOI can demonstrate the fetal blood supply,the presence of intrauterine hypoxia and so on.Measurement of fetal AOI Doppler spectrum and related hemodynamic parameters may provide reliable indicators for early detection and positive intervention in fetal growth retardation,which is of great significance for increasing the detection rate of FGR and reducing the incidence and mortality of perinatal period.The research progresses of hemodynamics in AOI of fetuses during the second and third trimester were reviewed in this article.

Research progresses of hemodynamics in aortic isthmus during fetal period / 中国医学影像技术

In the fetal circulation,the right and left cardiovascular system are positioned in parallel,and the aortic isthmus behaves as a shunt that connecting both up-and downstream circulations,allowing the fetuses to increase or reduce the amount of blood directed to the brain and heart depending on the degree of oxygen supply from the placenta.Doppler blood flow waveform of the fetal aortic isthmus can be obtained from the traditional longitudinal aortic arch view or the more recently described three vessels and trachea view of the fetal upper mediastinum.The aortic isthmus blood flow has a characteristic shape with end-systolic notch during the third trimester pregnancy and gradually deepen with the increase of gestational age.Doppler blood flow waveform of the aortic isthmus is closely related to fetal brain and heart function,and its reverse signal in the diastolic phase shows the poor intrauterine fetus.