Anatomy of thyroid and parathyroid glands and neurovascular relations

Clinical Applied Anatomy in Trans-Areolar Endoscopic Thyroidectomy: Crucial Anatomical Landmarks

Introduction: Endoscopic thyroidectomy (ET) has been successfully established as an excellent surgical approach. This study summarizes and describes the crucial anatomical landmarks for clinical applied anatomy in trans-areolar ET, which may help further improve the quality and safety of trans-areolar ET. Materials and Methods: Five hundred forty patients who underwent trans-areolar ET from January 2015 to June 2018 at our institution were evaluated. Several crucial anatomical landmarks were described during the surgical procedures. The surgical outcomes, including the operative time, conversion, intraoperative blood loss, postoperative complications, and postoperative stay, were collected. Results: All patients successfully underwent trans-areolar ET without conversion. The mean operative time was 142.18 ± 49.91 minutes (150.84 ± 50.32 minutes for total thyroidectomy and 110.20 ± 32.4 for lobectomy with isthmusectomy). The mean intraoperative blood loss was 20.45 ± 10.89 mL. The postoperative stay was 5.42 ± 1.49 days. The postoperative complication rate was 7.78%, including transient hypocalcemia in 30 patients, transient recurrent laryngeal nerve palsy in 3 patients, and skin ecchymosis in 9 patients. Conclusions: An understanding of crucial anatomical landmarks for clinical applied anatomy may improve the quality and safety of trans-areolar ET and subsequently help promote the development of ET.

Postoperative Hypoparathyroidism in Thyroid Surgery: Anatomic-Surgical Mapping of the Parathyroids and Implications for Thyroid Surgery

Hypoparathyroidism remains one of the most common complications in thyroid surgery. This study aims for an improved understanding of the complexity of the blood supply and the localisation of the parathyroids compared to the two most important intraoperative landmarks: the inferior laryngeal nerve (ILN) and Zuckerkandl's tubercle (ZT). We examined 103 laryngeal compounds to classify the blood supply and the localisation of the parathyroids. For intraoperative localisation we defined a Cartesian coordinate system with the ZT plane as x-axis and the course of the inferior laryngeal nerve as y-axis. The inferior thyroid artery (ITA) mainly supplies the parathyroids, whereas the superior thyroid artery provides a backup supply. It must be pointed out that 8.2% of parathyroids receive their blood directly from the thyroid gland. 73.5% of all parathyroids lie within 1 cm of the ILN and 1 cm cranial and 2.5 cm caudal to the ZT plane. Our described perimeters mark the most crucial areas during surgery and provide the surgeon with an anatomic mapping showing areas of special carefulness needed. One should keep bearing in mind all possible blood supply types of the parathyroids and therefore all branches should be handled with care.

[Ectopic tissue of the thyroid gland and the parathyroid glands]

Ectopic thyroid tissue results from developmental defects of the early stages of thyroid embryogenesis, in which the median thyroid anlage descends from the floor of the mouth to its final pre-tracheal position. The most common sites of ectopic thyroid tissue are accordingly in the area of the floor of the mouth and in the course of the thyroglossal duct. Rare localizations are intrathoracic (mediastinal, cardiac, pulmonary) and sub-diaphragmatic (including the adrenals, liver, gall bladder, and gastrointestinal tract). The most important differential diagnosis of ectopic thyroid is metastasis of differentiated thyroid carcinoma.By contrast, the term parathyroidectopy is not uniformly defined. Usually, the cervical-central localizations are referred to as "positional variants" (with the exception of the maxillary sinus and high parapharyngeal), whereas the cervical-lateral localizations (carotid sheath, vagus nerve) and those below the brachiocephalic and mediastinal positions (extraligamentary, aortopulmonary window, paravagal) and other rare localizations are classified as "ectopic parathyroid tissue". Parathyroidectomy is very common (in autopsy studies in 28 to 42.8% of all humans). In the context of primary hyperparathyroidism (pHPT), there is a prevalence of 6.3 to 16% of ectopic hyperfunctional parathyroid tissue (predominantly adenomas), which play an important role in the surgical treatment of pHPT.

Morphometric Differences in the Recurrent Laryngeal Nerve in Patients with Vocal Fold Paralysis

OBJECTIVES

Injury to the recurrent laryngeal nerve (RLN), if severe enough, can result in vocal fold paralysis. Reinnervation surgery can improve patient outcomes, but previous studies have reported a negative correlation between time since onset of paralysis and surgical outcomes. The ability of the paralyzed nerve to serve as a conduit for donor nerve fibers may be a factor in the success of reinnervation; however, changes in RLN composition after paralysis have not been well studied. Therefore, we investigated the morphometric composition of explanted RLN sections from patients who had experienced vocal fold paralysis for varying length of times.

METHODS

Nine nerve sections from unilateral vocal fold paralysis (UVP) patients and seven control nerve sections were analyzed for morphometric parameters including fascicular area, fiber count, fiber density, fiber packing, mean g-ratio, and fiber diameter distribution. Nerves from UVP patients were also compared as a function of time since UVP onset.

RESULTS

In comparison to control nerves, paralyzed nerves were found to have significantly lower fiber densities and fiber packing, higher mean g-ratio values, and a shift in diameter distributions toward smaller diameter fibers. With respect to paralysis duration, no significant differences were observed except in fiber diameter distributions, where those with paralysis for >2 years had distributions that were significantly shifted toward smaller diameter fibers.

CONCLUSIONS

The morphometric data presented here suggest that correlations between the time since onset of vocal fold paralysis and reinnervation outcomes may be due to fiber size changes in the paralyzed nerve over time.

Design of a predictive score to assess the risk of developing hypocalcemia after total thyroidectomy. A retrospective study

Background: Temporary hypocalcemia is the most common complication in patients after total thyroidectomy. To date, according to the literature, various predictors of the above complication have been proposed, but none of them seems to be effective enough. Objectives: The aim of this study was to develop a reliable predictive tool for biochemical hypocalcemia in the first 48 hrs after total thyroidectomy without central dissection by analyzing several parameters relevant to this operation and to suggest a new score. Methods: A retrospective study was performed on patients who had undergone total thyroidectomy without central neck dissection from October 2017 until January 2018. Data were collected from 36 patients and studied if there was a statistically significant relationship between the risk of hypocalcemia and 10 preselected prognostic factors. Results: The prognostic score was formed, which included the 6 factors that showed a statistically significant relationship. Moreover, an extensive check of the predictive value of the above score was performed. It was found, therefore, that at a value of 3 and above the sensitivity was 100%, the specificity 79.16%, the positive prognostic value (PPV) 70.58% and the negative predictive value (NPV) 100%. Conclusions: High sensitivity of CaReBe'S TiP score makes it feasible to predict patients with postoperative hypocalcemia. High NPV would allow surgeons to exclude patients with a score less than 3 from supplementary calcium medication and achieve a shorter hospitalization for them.

Diagnostic pitfalls in a cystic ectopic intrathyroidal parathyroid adenoma mimicking a nodular goiter: A care-compliant case report

RATIONALE

Cystic parathyroid adenomas are rare and seldom arise in ectopically located glands which may be found within the carotid sheath, mediastinum, thymus, or thyroid grand. They cannot be detected consistently by any imaging methods. Unusual symptoms may bring about certain pitfalls and difficulties for the diagnosis of primary hyperparathyroidism (PHPT) caused by cystic parathyroid adenomas. Until now, there are no specific guidelines on the management of cystic ectopic intrathyroidal parathyroid adenoma (ETPA).

PATIENT CONCERNS

An 82-year-old male musician presented abrupt thyroid enlargement, hoarseness, and trachea compression when he was playing the clarinet. Thyroid and renal function tests were normal. Serum-free calcium and parathyroid hormone (PTH) were in high concentration. Thyroid ultrasonography (US) detected a giant and cystic nodule within right thyroid lobe, which is the very image of cystic nodular goiter. Parathyroid US was negative. The cystic nodule had a decreasing radioactive uptake of Technetium-99m-methoxyisobutylisonitrile (Tc-MIBI). At patient's request, the invasive fine-needle aspiration (FNA) was not conducted.

DIAGNOSES

The patient was initially diagnosed as cystic nodular goiter and inconclusive PHPT.

INTERVENTIONS

Enucleation of solitary cystic intrathyroidal nodule was conducted.

OUTCOMES

The cystic nodule strongly resembled a nodular goiter grossly, but it was proved cystic ETPA by histopathology. Postoperative follow-ups found that serum-free calcium and PTH decreased sharply into normal range, and hoarseness and trachea displacement were obviously improved.

LESSONS

The diagnosis of cystic ETPA is easily overlooked for its rarity. Diagnostic pitfalls, including atypical symptoms, inconclusive imaging manifestation, and unidentified gross specimen, are highlighted. They make the diagnosis of PHPT caused by cystic ETPA challenging. Patients would rather choose surgical excision directly than invasive FNA. Acute hemorrhage of the preexisting ETPA may account for the cystic degeneration.

Ultrasonographic study of the incidence of pyramidal lobe and agenesis of the thyroid isthmus in Nnewi population

Introduction: Ultrasound is the most reliable imaging modality for thyroid evaluation due to the limitations in the clinical examination of this gland. Thyroid gland developmental anomalies are rare. Most of its variations are due to the persistence of the thyroglossal duct and the absence of the isthmus. The aim of this study was to determine the incidence of pyramidal lobe and agenesis of the thyroid isthmus in Nnewi population using ultrasound. Materials and method: A total of 321 subjects resident in Nnewi, including 167 males and 154 females, were randomized. A written consent was obtained from all patients. The subjects were aged between 18 and 35 years. This was a prospective cross-sectional study. Thyroid glands were scanned using a 2-dimensional ultrasound machine with a 7.5 MHz transducer; model Siemens Sonoline Prima which was made in Japan for Siemens Medical System Incorporated, ultrasound Group, Issaquah, WA, 98029-7002, USA. Results: The study revealed no incidence of pyramidal lobe and agenesis of the thyroid isthmus in the study population. Conclusion: This study has clearly demonstrated no incidence of pyramidal lobe and agenesis of the thyroid isthmus in subjects resident in Nnewi, Nigeria.

The application of subcapsular saline injection during bilateral axillo-breast approach robotic thyroidectomy: a preliminary report

PURPOSE

Saving the parathyroid gland during robotic thyroidectomy is challenging. This study evaluated the application of a novel method, subcapsular saline injection (SCASI), to save the parathyroid gland during bilateral axillo-breast approach (BABA) robotic total thyroidectomy.

METHODS

Of the 81 included patients operated on from 2014 to 2016, 31 and 50 underwent BABA robotic total thyroidectomy with and without SCASI, respectively. Serum concentrations of parathyroid hormone (PTH), calcium, and ionized calcium were measured at 1 day and 9 months postoperatively. Transient hypoparathyroidism was defined as PTH < 10.0 pg/mL after 1 day and permanent hypoparathyroidism as PTH < 15.0 pg/mL at 9 months.

RESULTS

There were no significant clinicopathologic differences between the two groups. The rate of transient hypoparathyroidism was significantly lower in the SCASI group than in the non-SCASI group [16.1% (5/31) vs. 44% (22/50), p < 0.01]. However, the rates of permanent hypoparathyroidism [0% (0/31) vs. 4% (2/50), p = 0.699] did not differ significantly.

CONCLUSIONS

SCASI is a feasible and safe method of saving the parathyroid gland during BABA robotic total thyroidectomy.

Decision making for the central compartment in differentiated thyroid cancer

The central compartment is a common site for nodal spread from differentiated thyroid carcinoma, often occurring in patients without clinical or ultrasonographic (US) evidence of neck lymph node metastasis (cN0). However, the role of elective central compartment neck dissection (CND) among patients with DTC remains controversial. We performed a systematic literature review, also including review of international guidelines, with discussion of anatomic and technical aspects, as well as risks and benefits of performing elective CND. The recent literature does not uniformly support or refute elective CND in patients with DTC, and therefore an individualized approach is warranted which considers individual surgeon experience, including individual recurrence and complication rates. Patients (especially older males) with large tumors (>4 cm) and extrathyroidal extension are more likely to benefit from elective CND, but elective CND also increases risk for hypoparathyroidism and recurrent nerve injury, especially when operated by low-volume surgeons. Individual surgeons who perform elective CND must ensure the number of central compartment dissections needed to prevent one recurrence (number needed to treat) is not disproportionate to their individual number of central compartment dissections per related complication (number needed to harm).

Variations in the origins of the thyroid arteries on CT angiography

OBJECTIVE

To investigate the anatomical variations in the origins of the thyroid arteries on CT angiography images.

METHODS

The presence and the origins of the superior thyroid artery, the inferior thyroid artery, and the thyroidea ima artery were retrospectively evaluated based on carotid CT angiography examinations. The bifurcation level of the common carotid artery with respect to the cervical vertebrae and disc spaces was also determined. A total of 640 patients were included in the study.

RESULTS

The right and left superior thyroid arteries arose from the external carotid artery in 413 (64.5%) and 254 (39.7%) patients, from the bifurcation of the common carotid artery in 131 (20.5%) and 148 (23.1%) patients, and from the common carotid artery in 90 (14.1%) and 226 (35.3%) patients, respectively. We could not observe the right and the left superior thyroid arteries in 6 (0.9%) and 12 (1.9%) of the patients, respectively. However, the right and left inferior thyroid arteries were not identified in 14 (2.2%) and 45 (7%) of the patients, respectively. The thyroidea ima artery was detected in 2.3% of the patients.

CONCLUSION

The visualization of thyroid arteries on CT angiography images enables the anatomy of the arterial supply system of the thyroid gland to be explored in a noninvasive manner prior to surgery.

Intraoperative Assessment of Parathyroid Viability using Laser Speckle Contrast Imaging

Post-surgical hypoparathyroidism and hypocalcemia are known to occur after nearly 50% of all thyroid surgeries as a result of accidental disruption of blood supply to healthy parathyroid glands, which are responsible for regulating calcium. However, there are currently no clinical methods for accurately identifying compromised glands and the surgeon relies on visual assessment alone to determine if any gland(s) should be excised and auto-transplanted. Here, we present Laser Speckle Contrast Imaging (LSCI) for real-time assessment of parathyroid viability. Taking an experienced surgeon's visual assessment as the gold standard, LSCI can be used to distinguish between well vascularized (n = 32) and compromised (n = 27) parathyroid glands during thyroid surgery with an accuracy of 91.5%. Ability to detect vascular compromise with LSCI was validated in parathyroidectomies. Results showed that this technique is able to detect parathyroid gland devascularization before it is visually apparent to the surgeon. Measurements can be performed in real-time and without the need to turn off operating room lights. LSCI shows promise as a real-time, contrast-free, objective method for helping reduce hypoparathyroidism after thyroid surgery.

Subtotal Parathyroidectomy and Relocation of the Parathyroid Remnant for Renal Hyperparathyroidism: modification of a traditional operation

Background

We describe a modification of the conventional subtotal parathyroidectomy operation where the parathyroid gland(s) remnant is repositioned with intact vascular supply to a plane superficial to the infrahyoid strap muscles and immediately under the skin incision. This technique called Subtotal Parathyroidectomy and Remnant Relocation (SPARE) retains all the metabolic advantages of the conventional operation with the added advantage of easier identification of a recurrent hyperplastic remnant if re-exploration becomes necessary.

Methods

In the SPARE technique, four parathyroid glands were identified and the quality of each gland and the length of each vascular pedicle to the parathyroid glands were assessed. The optimal parathyroid gland was relocated to a plane superficial to the strap muscles. The remainder of the glands were removed.

Results

In total, 30 patients with hyperparathyroidism secondary to renal failure (HSRF) underwent parathyroidectomy with the SPARE technique. The mean age was 53.1±12.5 years and median follow-up was 17.1 months (range 1-78.9 months). There were no recurrent laryngeal nerve (RLN) injuries or hematomas. The pre- and post-operative value for corrected calcium and PTH were 158.4±109.4 pmol/L and 11.4±12.1 pmol/L, respectively (p < 0.05). Three recurrences were noted (10.0%), with a mean time to recurrence of 15.3±6.6 months. One patient had excision of the remnant parathyroid glands performed under local anaesthetic (29 min); one had re-exploration performed under general anaesthetic (81 min), and one was managed medically.

Conclusion

We described a novel parathyroidectomy technique for patients with HSRF, which provides the advantages of conventional subtotal parathyroidectomy while mitigating the challenges of thyroid bed re-exploration when recurrences arise.

Per Operative Study of Relation of Zuckerkandl Tubercle with Recurrent Laryngeal Nerve in Thyroid Surgery

To identify Zuckerkandl tubercle and to determine relationship between the recurrent laryngeal nerve and Zuckerkandl tubercle (ZT). Peroperative study. Intraoperatively Zuckerkandl tubercle was identified. Size of the thyroid lobe and Zuckerkandl tubercle were co-related and direction of tubercle in relation to recurrent laryngeal nerve was examined. Grading of tubercle on the basis of size was done. We studied its direction and relation with recurrent laryngeal nerve. ZT was identified in 87.86% (179 out of 206) of cases. In the study amongst the 179 cases in whom ZT could be identified, ZT was found on the right side (85.41% i.e. 123 out of 144), 81.41% (92 out of 113) to the left side and 15.68% (8 out of 51) were B/L. ZT was found posterior to the tubercle in 97.22%(175 out of 179) cases and anterior to the tubercle in 2.77% (5 out of 179) cases. The relationship between recurrent laryngeal nerve and ITA was studied. ITA was anterior to RLN (in 70.89%) and posterior to RLN in 29.10%. Thus, ZT is an important landmark for identification of RLN during thyroidectomy (p value 0.001). Level of evidence III.

Lymph node metastasis characteristics of papillary thyroid carcinoma located in the isthmus: A single-center analysis

The frequency and pattern of lymph node metastasis and the extent of dissection for isthmic papillary thyroid carcinoma (PTC) remain unclear, and the aim of this present study was to evaluate these characteristics and to attempt to detect the best surgical protocol for isthmic PTCs. A total of 3185 consecutive patients with PTCs were reviewed. Of these patients, 47 with a single isthmic PTC were enrolled in our study, and matched 47 patients with a single PTC located in the unilateral lobe were randomly selected and added for comparison of their baseline tumor characteristics and lymph node metastasis characteristics. Univariate and multivariate analyses were performed to determine the risk factors for central lymph node metastasis in PTCs. The isthmic PTCs showed a higher rate of capsule invasion (P = .013) and advanced pathological N stage (P = .038) compared to the PTCs located in the lobe; meanwhile, pathological evidence of central lymph node metastasis (P = .040) was more frequent in the isthmic PTC group than in the control group. The univariate and multivariate analyses indicated that the tumors located in the isthmus (hazard ratio [HR]: 2.769; 95% confidence interval [CI]: 1.124-6.826; P = .027) and those with advanced (T2-4) pathological classifications (HR: 4.282; 95% CI: 1.224-14.976; P = .023) were independent risk factors for central lymph node metastasis in PTC patients. Due to the higher rate of pathological central lymph node metastasis and independent risk factors for central lymph node metastasis, total thyroidectomy, and bilateral central lymph node dissection should be considered the standard surgical protocol for isthmic PTCs.

Anatomic Characteristics, Identification, and Protection of the Nonrecurrent Laryngeal Nerve during Thyroidectomy

Objective

We aimed to investigate the anatomical features and variation pattern of the nonrecurrent laryngeal nerve (NRLN), summarize the methods for identifying the NRLN before and during thyroidectomy, and share experiences regarding preventing and treating its injury.

Study Design

Retrospective case data analysis.

Setting

First Affiliated Hospital of Harbin Medical University.

Subjects and Methods

Between January 2002 and May 2016, 7392 patients underwent thyroidectomy in our hospital. Of them, 28 patients with NRLN were identified, and their clinical data were retrospectively analyzed.

Results

This study included 7392 patients in which the recurrent laryngeal nerves (RLNs) were routinely identified during surgery. The presence of NRLN was intraoperatively confirmed in 28 patients. All the NRLNs were located on the right side and its overall incidence was 0.37%. Five of the NRLNs were classified as type I, 19 as type IIa, and 4 as type IIb. Of the 28 cases, 4 NRLNs were injured during surgery, in which primary end-to-end anastomosis or local seal with corticosteroid injection was performed as a remedy. In the 4 patients with NRLN injury, 2 presented with postoperative hoarseness that indicated vocal cord paralysis confirmed by laryngoscope; the other 2 patients’ voices had no significant changes.

Conclusion

The NRLN, which is rare in clinical practice and predominantly right-sided, is anatomically more complex and variant at a higher risk of surgical injury. The key factors to accurately identify NRLN and to effectively prevent its injury include careful interpretation of auxiliary examination results before surgery, raising awareness of its presence, meticulous dissection, and routine exposure of the RLN during surgery.

Preserving Parathyroid Gland Vasculature to Reduce Post-thyroidectomy Hypocalcemia

BACKGROUND

The failure to preserve parathyroid function in patients who have undergone total thyroidectomy is of major concern, because hypocalcemia is difficult to prevent and remains a common postoperative complication. Here, we describe procedures designed to preserve the vasculature supplying the parathyroid glands and examine both recent outcomes and retrospective reports of results obtained prior to the application of these preservation techniques.

METHODS

Our technique for preserving parathyroid function during thyroidectomy was adopted in 2009 and involves separating a relatively long segment of a vessel distally from the thyroid gland. We reviewed the medical records of 1,411 patients who underwent total thyroidectomy, with or without lateral neck dissection, at the Samsung Medical Center from January 2006 through June 2014 to determine outcomes. Patients were divided into three groups according to the time period during which the surgery took place: Group A, 2006-2008 (before the vasculature-preserving technique was applied); Group B, 2009-2011 (the time when the technique was first adopted); and Group C, 2012-2014 (more recent results of the technique). We analyzed the incidence of hypoparathyroidism in the three groups, as well as risk factors that influenced its development.

RESULTS

The rates of transient and permanent hypoparathyroidism in Group A were 25.4 and 4.3 %, respectively. However, the incidence of hypoparathyroidism decreased significantly over time after the vasculature-preserving procedure was adopted. Transient hypoparathyroidism developed in 4.8 % of Group C patients, and only four (0.7 %) of the 565 patients in this group required calcium supplementation, despite the fact that a greater number of patients were included who underwent total thyroidectomy combined with lateral neck dissection. Although female sex and lateral neck dissection tended to increase the rate of transient hypoparathyroidism, multivariate analysis showed that the vasculature-preserving procedure was the only significant risk factor related to postoperative hypoparathyroidism.

CONCLUSION

The blood flow of the final branch to the parathyroid gland is mostly in the lateral-to-medial direction; therefore, mobilization and preservation of the vessels lateral to the gland is essential to prevent devascularization of the parathyroid gland.

Unilateral occurrence of five different thyroid arteries-a need of terminological systematization: a case report

This article highlights an unusual and unilateral variation in the blood supply to the inferior portion of the thyroid gland observed on the right lobe during anatomy dissection course. The rare variation of the occurrence of two anomalous arteries: the middle thyroid artery and the aberrant accessory inferior thyroid artery, and one uncommon variant, the thyroid ima artery, was detected in an adult female cadaver. The two generally constant arteries, the superior thyroid artery and the inferior thyroid artery, have been found in their usual anatomical location. Both the middle thyroid artery and aberrant accessory inferior thyroid artery arose from the right common carotid artery. The middle thyroid artery coursed as a very short branch ventromedially to enter the inferior lateral portion of the right lobe of the thyroid gland. It was at the same level, in which the inferior thyroid artery reached the lateral border of the thyroid gland. The aberrant accessory inferior thyroid artery originated similarly, from the ventromedial surface of the right common carotid artery and passed to supply the inferior pole of the right lobe. The thyroid ima artery was found to arise from the brachiocephalic trunk, entering the isthmus of the thyroid gland. Information about the embryological background might be helpful to clarify why such a type of variation occurs. It is necessary to understand the possible existence of this anomaly, to carry out successful radical neck dissection and to minimize the risk of postoperative complications in patients.

Enhanced identification and functional protective role of carbon nanoparticles on parathyroid in thyroid cancer surgery: A retrospective Chinese population study

The aim of this study was to determine the effects of nanocarbon particles in combination with meticulous capsular dissection on enhancing the identification and protecting the function of parathyroid glands in thyroid cancer surgery.The data of 97 patients with papillary thyroid tumors diagnosed and treated at the Second Affiliated Hospital, Harbin Medical University between January 2014 and February 2015 were reviewed. Data regarding the sex, age, calcium and parathyroid hormone (PTH) levels, tumor size, multifocality, T stage, and extrathyroid invasion were collected. The incidence of surgeries in which the parathyroid glands were cut mistakenly, the concentration of serum calcium and parathyroid hormone before surgery (baseline) and after surgery on days 1, 3, and 7, and 1 and 6 months in the patients of the two groups (the nanocarbon and control groups) were analyzed.Fifty-two patients underwent meticulous capsular dissection combined with nanocarbon treatment (nanocarbon group), and 45 underwent meticulous capsular dissection alone (control group). The nanocarbon group showed a significantly higher total and average number of revealed parathyroid glands (average number is the mean for different individuals have different number) and a lower incidence of the parathyroid glands being mistakenly cut, in addition to a lower level of hypoparathyroidism than control group following surgery (P < 0.05). Serum calcium and PTH levels were significantly lower in patients from both groups after surgery on days 1, 3, and 7 and after 1 month, compared with the preoperative levels (P < 0.05). Compared with the control group, the serum calcium and PTH levels were significantly higher in the nanocarbon group after surgery on days 1, 3, 7, than in the control group.Treatment with nanocarbon in combination with meticulous capsular dissection can significantly facilitate the identification of the parathyroid in thyroid cancer surgery, reduce the risk of mistakenly cutting the parathyroid, and reduce the incidence of postoperative hypoparathyroidism.

A case report of mediastinal ectopic parathyroid adenoma presented as parathyroid crisis localized by SPECT/CT

INTRODUCTION

Parathyroid crisis due to ectopic parathyroid adenomas can pose diagnostic and management challenges, since it is quite rare in clinical practice.

CLINICAL FINDINGS/PATIENT CONCERNS

A 67-year-old Chinese male presented as a parathyroid crisis due to an ectopic mediastinal parathyroid adenoma with his serum calcium and PTH markedly increased in short time. An ultrasonography and computed tomography (CT) scan of the neck did not reveal any parathyroid adenoma. Thoracic CT detected a contrast-enhanced mass in the mediastinum. Although the ectopic location is difficult to appreciate on anterior planar technetium-99m-sestamibi scintigraphy views but has been accurately localized with single photon-emission computed tomography/computed tomography. After fluid resuscitation, loop diuretic, and calcitonin treatment, a thoracoscope surgery was performed. The histopathology of the mediastinal nodule was consistent with a parathyroid adenoma. Hypocalcemia due to hungry bone syndrome occurred after surgery and was resolved quickly with large-dose calcium and calcitriol supplementation. He is asymptomatic and has normal serum calcium and PTH levels on regular follow-up.

DIAGNOSES

The ultrasonography, CT, sestamibi, and single photon-emission computed tomography/computed tomography provide limited sensitivity in the detecting ectopic parathyroid adenomas alone. The combination of these techniques has incremental value in localizing ectopic parathyroid adenomas over either technique alone.

CONCLUSION

Any parathyroid crisis without parathyroid adenoma in the neck should alert physicians to search for ectopic locations through combination of imaging techniques.

The differential diagnosis of central compartment radioactive iodine uptake after thyroidectomy: anatomic and surgical considerations

OBJECTIVE

Foci of increased radioactive iodine (RAI) uptake in the thyroid bed following total thyroidectomy (TT) indicate residual thyroid tissue that may be benign or malignant. The use of postoperative RAI therapy in the form of remnant ablation, adjuvant therapy, or therapeutic intervention is often followed by a posttherapy scan. Our objective is to improve the clinician's understanding of the anatomic complexity of this region and to enhance the interpretation of postoperative scans.

METHODS

We conducted a comprehensive review of the literature evaluating RAI uptake in the central compartment following thyroid cancer treatment and literature related to anatomic nuances associated with this region. Thirty-eight articles were selected.

RESULTS

Through extensive surgical experience and a literature review, we identified the 5 most important anatomic considerations for clinicians to understand in the interpretation of foci of increased RAI uptake in the thyroid bed on a diagnostic scan: 1) residual benign thyroid tissue at the level of the posterior thyroid ligament, 2) residual benign thyroid tissue at the superior portion of the pyramidal lobe and/or superior poles of the lateral thyroid lobes, 3) residual benign thyroid tissue that was left attached to a parathyroid gland in order to preserve its vascularity, 4) ectopic benign thyroid tissue, and 5) malignant thyroid tissue that has metastasized to central compartment nodes or invaded visceral structures.

CONCLUSION

By correlating anatomic description, medical illustrations, surgical photos, and scans, we have attempted to clarify the reasons for foci of increased uptake following TT to improve the clinician's understanding of the anatomic complexity of this region.

Medicolegal implications of surgical errors and complications in neck surgery: A review based on the Italian current legislation

Aim of the present paper is the review of the principal complications associated to endocrine neck surgery considering how expertise, full adoption of guidelines, appropriate technology and proper informed consent may limit the medicolegal claims at the light of the incoming new regulation of the medical professional legal responsibility. A literature search, using the Medline/PubMed database for full-length papers, was used. Postoperative recurrent laryngeal nerve (RLN) palsy and hypoparathy-roidism remain the principal causes of surgical malpractice claims . In the procedure of neck lymphadenctomy intra-operative haemorrhage, thoracic duct injury, injuries to loco-regional nerves can be observed and can be source of claims. After many years of increased medicolegal litigations, the Italian government is proposing a drastic change in the regulations of supposed medical malpractice in order to guarantee the patient's right to a safe treatment and in the meantime to defend clinicians from often unmotivated and prejudicial legal cases. Surgical errors and complications in neck surgery are a relevant clinical issue. Only the combination of surgical and clinical expertise, application of guidelines, appropriate technology and a routinely use of specific informed consent can contain potential medicolegal implications.

Analysis of the incidence and factors predictive of inadvertent parathyroidectomy during thyroid surgery

BACKGROUND

Inadvertent (or incidental) parathyroidectomy can occur during thyroidectomy. However, the factors associated with inadvertent parathyroidectomy remain unclear. This study aimed to report the rate of inadvertent parathyroidectomy during thyroidectomy and associated risk factors.

METHODS

Variables including fine needle aspiration cytology findings, age, sex, thyroid weight, concurrent neck dissection, extent of thyroidectomy, and the presence of cancer and parathyroid tissue within the specimen were recorded for 266 patients. The incidence of post-operative hypocalcaemia was also recorded. Univariate and multivariate analysis were performed to identify factors associated with inadvertent parathyroidectomy.

RESULTS

The inadvertent parathyroidectomy rate was 16 per cent. Univariate analysis revealed that cancer and concurrent neck dissection predicted inadvertent parathyroidectomy. On multivariate analysis, only concurrent neck dissection remained an independent predictor of inadvertent parathyroidectomy: it was associated with a fourfold increase in inadvertent parathyroidectomy.

CONCLUSION

The inadvertent parathyroidectomy rate was 16 per cent and concurrent neck dissection was identified as an independent predictor of inadvertent parathyroidectomy.

Towards automated spectroscopic tissue classification in thyroid and parathyroid surgery

BACKGROUND

In (para-)thyroid surgery iatrogenic parathyroid injury should be prevented. To aid the surgeons' eye, a camera system enabling parathyroid-specific image enhancement would be useful. Hyperspectral camera technology might work, provided that the spectral signature of parathyroid tissue offers enough specific features to be reliably and automatically distinguished from surrounding tissues. As a first step to investigate this, we examined the feasibility of wide band diffuse reflectance spectroscopy (DRS) for automated spectroscopic tissue classification, using silicon (Si) and indium-gallium-arsenide (InGaAs) sensors.

METHODS

DRS (350-1830 nm) was performed during (para-)thyroid resections. From the acquired spectra 36 features at predefined wavelengths were extracted. The best features for classification of parathyroid from adipose or thyroid were assessed by binary logistic regression for Si- and InGaAs-sensor ranges. Classification performance was evaluated by leave-one-out cross-validation.

RESULTS

In 19 patients 299 spectra were recorded (62 tissue sites: thyroid = 23, parathyroid = 21, adipose = 18). Classification accuracy of parathyroid-adipose was, respectively, 79% (Si), 82% (InGaAs) and 97% (Si/InGaAs combined). Parathyroid-thyroid classification accuracies were 80% (Si), 75% (InGaAs), 82% (Si/InGaAs combined).

CONCLUSIONS

Si and InGaAs sensors are fairly accurate for automated spectroscopic classification of parathyroid, adipose and thyroid tissues. Combination of both sensor technologies improves accuracy. Follow-up research, aimed towards hyperspectral imaging seems justified. Copyright © 2016 John Wiley & Sons, Ltd.

Lingual Thyroid Ectopia: Diagnostic SPECT/CT Imaging and Radioactive Iodine Treatment

BACKGROUND

Lingual thyroid is a rare abnormality of thyroid development that is usually treated conservatively with levothyroxine replacement. Rarely, it becomes large enough to cause obstructive symptoms in the oral cavity, requiring definitive treatment.

PATIENT FINDINGS

This study reports on three patients with lingual thyroid treated with radioactive iodine-131 ((131)I) with successful radioablation of their ectopic thyroid tissues. Measurement of 24-hour radioactive iodine uptake within thyroidal tissues and hybrid single-photon emission computed tomography/computed tomography imaging using either iodine-123 or technetium-99m pertechnetate scans were performed in all patients demonstrating the location and size of lingual thyroid and absence of an orthotopic thyroid gland.

SUMMARY

The aim of this study was to describe nonsurgical management of obstructive lingual thyroid tissue with (131)I therapy for lingual thyroid radioablation. Patients were prepared with a low-iodine diet and levothyroxine withdrawal prior to radioablation for optimizing (131)I uptake in ectopic thyroid tissues. Hybrid single-photon emission computed tomography/computed tomography measurement of anatomic size of lingual thyroid tissue and radioactive iodine uptake guided the selection of therapeutic doses, resulting in administration of 10.7, 17.5, and 15.4 mCi of (131)I, respectively. There were no post-therapy complications, and clinical follow-up demonstrated resolution of obstructive oropharyngeal symptoms.

CONCLUSIONS

Ectopic lingual thyroid tissue is rarely associated with obstructive oropharyngeal symptoms due to progressive enlargement. Radioiodine therapy with (131)I is an effective treatment modality for ablation of ectopic thyroid tissue as an alternative to surgery.

The nonrecurrent laryngeal nerve: A clinical anatomic mapping with regard to intraoperative neuromonitoring

BACKGROUND

We investigated the nonrecurrent inferior laryngeal nerve (nrILN), an important variant in the course of the inferior laryngeal nerve (ILN; 0.5-6.0%). Its importance was demonstrated in a clinical case as well as in cadaver specimens, and the pattern was identified with intraoperative neuromonitoring (IONM).

METHODS

The ILN and the presence of an nrILN were investigated in 36 formaldehyde-embalmed specimens. Our anatomic findings showed differences in the anatomic course of the ILN and thus produced possible explanations for different IONM signals that would correlate with differences in the anatomic course of the ILN. Preoperative ultrasonographic evaluation of the brachiocephalic trunk and the recurrent laryngeal nerve were used for the exclusion or identification of an nrILN, respectively.

RESULTS

We found 2 nrILNs (ascending, horizontal; 6%) in the anatomic specimens. These 2 specimens each showed an aberrant right subclavian artery (lusorial artery) and were, therefore, associated with the absence of a brachiocephalic trunk. The intraoperative case displayed a descending nrILN. Signals derived from the vagus nerve were positive if derived proximal to and negative if derived distal to the branching of an nrILN. By ultrasonographic identification of a normal brachiocephalic trunk, an nrILN could be excluded.

CONCLUSION

Surgeons need a working knowledge about nrILNs to avoid recurrent nerve palsy and should be familiar with all the possible course variations in the ILN when IONM signals are absent with vagal stimulation. Moreover, endocrine surgeons need to be able to interpret correctly negative as well as positive signals. Preoperative ultrasonography should ideally be performed, because the presence of a normal brachiocephalic trunk is a quick method to exclude or identify a nrILN.

[Avoidance and management of hypoparathyroidism after thyroid gland surgery]

Postoperative hypoparathyroidism after bilateral thyroid gland surgery or after interventions for recurrence is defined as intact parathyroid hormone levels (iPTH) < 15 pg/ml with simultaneous normal, below normal and markedly decreased serum calcium levels. After bilateral thyroid surgery and after reoperations a single iPTH measurement performed 12-24 h postoperatively can be used to predict parathyroid metabolism. Patients with an iPTH level ≥ 15 pg/ml may be discharged safely, patients with an iPTH < 10 pg/ml must be substituted with calcium and vitamin D and patients with an iPTH between 10 and 15 pg/ml (grey zone) may be discharged if a second measurement 48 h after surgery documents an iPTH ≥ 15 pg/ml. This procedure increases the length of hospital stay. Patients in the (grey zone) must be substituted. The iPTH level and its course determine the necessity, dose and length of calcium and vitamin D substitution.

Surgical options for primary hyperparathyroidism

Over the last two decades, surgery for primary hyperparathyroidism has evolved to offer a panel of procedures based on improvements in imaging, new technology and, consequently, novel surgical techniques. Multiple courses of action are possible, consistent with varying degrees of complexity. From the simplest scenario of a single adenoma localized by at least two preoperative tests in the context of sporadic primary hyperparathyroidism, to revision surgery related to recurrent, persistent or multiglandular disease, the surgeon has the opportunity to adapt his strategy. However, whatever surgical approach is used, even in the absence of formal guidelines, the clinical judgment of an experienced and skilled practitioner in endocrine surgery is the real guide and key of success in complex situations.

Non-functional parathyroid carcinoma: a case report and review of the literature

Non-functional parathyroid carcinoma is an exceedingly rare disease with 31 reported cases since 1909. Because of the scarce number of cases of non-functional parathyroid carcinoma, there are no evidence-based recommendations for its optimal treatment. Surgery, including en bloc resection of the carcinoma, ipsilateral thyroid lobe and isthmus together with a neck dissection only in case of lymph node involvement, is the main treatment for non-functioning parathyroid carcinoma. The patient usually has a poorer prognosis because of detection at advanced stages, the relative ineffectiveness of adjuvant treatment modalities and the lack of adequate parameters for clinical follow-up. In this report, we present a case of non-functional parathyroid carcinoma at our institution, and we review the previous literature to discuss the latest advances in the diagnosis and treatment of this rare disease.

Carbon nanoparticle-guided central lymph node dissection in clinically node-negative patients with papillary thyroid carcinoma

BACKGROUND

Distinguishing the involved lymph nodes from other tissues during surgery is critical for lymph node dissection. The purpose of this study was to assess the feasibility by using carbon nanoparticles as guidance for lymph node dissection in patients with papillary thyroid carcinoma (PTC).

METHODS

Eighty-one patients were injected with carbon nanoparticles (carbon nanoparticle group), whereas the other 81 patients were not (control group). Routine pathological examination was performed.

RESULTS

The lymph node dissection and metastatic lymph node dissection rates of the carbon nanoparticle group were significantly higher than that of the control group. In the carbon nanoparticle group, the number of mistakenly dissected parathyroid gland, the case number of postoperative hypocalcemia, the case number of postoperative hypoparathyroidism, and the recovery time from hypocalcemia were 4, 6, 8, and 2.33 ± 0.58 weeks, respectively, significantly less than 14, 17, 20, 3, and 3.8 ± 0.92 weeks in the control group (p < .05).

CONCLUSION

Carbon nanoparticles can be applied to more accurately guide the dissection of lymph nodes during thyroidectomy in patients with PTC. © 2015 Wiley Periodicals, Inc. Head Neck 38: 840-845, 2016.

Surgical strategy for primary hyperparathyreoidism with thyroid hemiagenesis

BACKGROUND

Thyroid hemiagenesis is a rare congenital anomaly, and still more rarely associated with primary hyperparathyroidism (pHPT). Due to the embryologic pathways of the thyroid and parathyroid glands, it remains unclear whether or not thyroid hemiagenesis may be linked to ipsilateral parathyroid agenesis, and consequently, surgical strategy for thyroid hemiagenesis associated pHPT (THAP) does not only depend on preoperative localization but also on the thyroid anomaly.

METHODS

Including the present case report, a total of nine cases with THAP retrieved from the literature were reviewed. Seven of nine cases had thyroid hemiagenesis on the left side, three out of nine showed a parathyroid adenoma on the contralateral side to the thyroid hemiagenesis.

CONCLUSIONS

Based on these cases, it can be concluded that the embryologic pathways of the thyroid and parathyroid glands are different, and in cases of THAP, parathyroid exploration should follow standard recommendations for pHPT surgery.

Papillary thyroid microcarcinoma in a thyroid pyramidal lobe

We report an extremely rare case of papillary thyroid microcarcinoma (PTMC) in the thyroid Epub ahead of print pyramidal lobe (TPL). A 48-year-old woman underwent ultrasound-guided fine-needle aspiration for a small thyroid nodule in the right lobe in local clinic, and it revealed a malignant cytology. On preoperative ultrasonography for tumor staging in our hospital, another small suspiciously malignant hypoechoic nodule was detected in the left TPL. Total thyroidectomy and central nodal dissection were performed. Histopathology confirmed PTMCs in the left TPL and both thyroid lobes. Ultrasonography for TPL should be required for complete evaluation of possible multifocality of thyroid malignancy.

Identification of parathyroid glands: anatomical study and surgical implications

While performing thyroid surgery, the unintentional lesion of parathyroid glands and laryngeal nerves results in a profound alteration in patient's quality of life. To minimize thyroid surgery morbidity, the surgeon must have an in-depth knowledge of the thyroid gland morphology and its anatomical relations in the anterior compartment of the neck. This work intended to simulate total thyroidectomies using cadaver parts and isolate fragments that may correspond to parathyroid glands. The thyroid glands and "eventual" parathyroid glands were then submitted to histological study. Ninety-two cadaver parts were used for macroscopic dissection. A total of 242 fragments were isolated, 154 of which were confirmed through histological study to be parathyroid glands. In 36 cases, all "eventual" parathyroid glands isolated during dissection were confirmed through histological verification. In 40 cases, some glands were confirmed. In 16 cases, none of the "eventual" parathyroid glands was confirmed. The 92 thyroid glands isolated during dissection were also submitted to histological study. In 21 thyroid glands, 16 parathyroid glands were identified in the histological cuts: 8 sub-capsular, 8 extra-capsular, 6 intra-thyroidal. There was no statistical difference between the dimensions of the parathyroid glands. Parathyroid gland identification and preservation are sometimes a challenge during thyroid surgery, difficulty that has been demonstrated during dissection of cadaver parts.

Thyroid surgery in children

Although surgical conditions of the thyroid gland are uncommon in children, the increased incidence of thyroid cancer, combined with the fact that children's hospitals are increasingly treating older adolescents, means that it is important that all pediatric surgeons have a knowledge of these conditions. Abnormalities of the thyroid can be associated with abnormalities of thyroid function (hyperthyroidism or hypothyroidism) and/or can be associated with symmetrical or asymmetrical enlargement of the gland.

Errors and mistakes in ultrasound diagnostics of the thyroid gland

Ultrasound examination of the thyroid gland permits to evaluate its size, echogenicity, margins, and stroma. An abnormal ultrasound image of the thyroid, accompanied by other diagnostic investigations, facilitates therapeutic decision-making. The ultrasound image of a normal thyroid gland does not change substantially with patient's age. Nevertheless, erroneous impressions in thyroid imaging reports are sometimes encountered. These are due to diagnostic pitfalls which cannot be prevented by either the continuing development of the imaging equipment, or the growing experience and skill of the practitioners. Our article discusses the most common mistakes encountered in US diagnostics of the thyroid, the elimination of which should improve the quality of both the ultrasound examination itself and its interpretation. We have outlined errors resulting from a faulty examination technique, the similarity of the neighboring anatomical structures, and anomalies present in the proximity of the thyroid gland. We have also pointed out the reasons for inaccurate assessment of a thyroid lesion image, such as having no access to clinical data or not taking them into account, as well as faulty qualification for a fine needle aspiration biopsy. We have presented guidelines aimed at limiting the number of misdiagnoses in thyroid diseases, and provided sonograms exemplifying diagnostic mistakes.

Pitfalls in sonographic evaluation of thyroid abnormalities

Ultrasound of the thyroid has become increasingly common, with evaluation of thyroid nodules representing the main indication for its use. While detection of thyroid nodules with modern high-resolution sonographic equipment is generally not a challenge, pitfalls may occur by which normal structures or pathology in neighboring organs are mistaken for thyroid nodules. Numerous reports in the literature describe various sonographic features of nodules in an attempt to stratify lesions into benign or malignant categories. While neither nodule size nor number is reliable, echogenicity, microcalcifcation, shape, and composition have been reported to be helpful in classifying thyroid nodules. No single feature should be used in isolation, and consensus guidelines have been established as to when fine-needle aspiration is indicated. Pitfalls remain in the evaluation of thyroid nodules demonstrating atypical features, such as cystic papillary carcinomas. Focal presentation of typically diffuse processes, such as Graves' disease and Hashimoto thyroiditis, may mimic malignant nodules, but carcinomas occur in these settings as well as in a background of normal thyroid parenchyma. Finally, because ultrasound is commonly used for surveillance of patients with thyroid carcinoma after thyroidectomy, sonographers should be familiar with the ultrasound appearance of disease recurrence and its mimics.

Neurological complications in thyroid surgery: a surgical point of view on laryngeal nerves

THE CERVICAL BRANCHES OF THE VAGUS NERVE THAT ARE PERTINENT TO ENDOCRINE SURGERY ARE THE SUPERIOR AND THE INFERIOR LARYNGEAL NERVES: their anatomical course in the neck places them at risk during thyroid surgery. The external branch of the superior laryngeal nerve (EB) is at risk during thyroid surgery because of its close anatomical relationship with the superior thyroid vessels and the superior thyroid pole region. The rate of EB injury (which leads to the paralysis of the cricothyroid muscle) varies from 0 to 58%. The identification of the EB during surgery helps avoiding both an accidental transection and an excessive stretching. When the nerve is not identified, the ligation of superior thyroid artery branches close to the thyroid gland is suggested, as well as the abstention from an indiscriminate use of energy-based devices that might damage it. The inferior laryngeal nerve (RLN) runs in the tracheoesophageal groove toward the larynx, close to the posterior aspect of the thyroid. It is the main motor nerve of the intrinsic laryngeal muscles, and also provides sensory innervation to the larynx. Its injury finally causes the paralysis of the omolateral vocal cord and various sensory alterations: the symptoms range from mild to severe hoarseness, to acute airway obstruction, and swallowing impairment. Permanent lesions of the RNL occur from 0.3 to 7% of cases, according to different factors. The surgeon must be aware of the possible anatomical variations of the nerve, which should be actively searched for and identified. Visual control and gentle dissection of RLN are imperative. The use of intraoperative nerve monitoring has been safely applied but, at the moment, its impact in the incidence of RLN injuries has not been clarified. In conclusion, despite a thorough surgical technique and the use of intraoperative neuromonitoring, the incidence of neurological complications after thyroid surgery cannot be suppressed, but should be maintained in a low range.

Preoperative Localization of Parathyroid Adenomas Using 4-Dimensional Computed Tomography: A Pictorial Essay

Accurate preoperative localization is the key to successful parathyroid surgery in the era of minimally invasive parathyroid surgery. This article presents and discusses the embryologic basis of parathyroid gland and ectopic location and different imaging modalities helpful in diagnosing and localizing parathyroid adenomas and/or hyperplasia. We also aim to review the current surgical concepts in treatment of parathyroid adenomas and/or hyperplasia, the utility of 4-dimensional computed tomography for accurate preoperative localization of hyperfunctioning parathyroid glands, imaging classification of adenomas and/or hyperplasia, and, finally, present some of the limitations of 4-dimensional computed tomography.

Thyroid papillary carcinoma arising in ectopic thyroid tissue within a branchial cleft cyst

Ectopic thyroid tissue comprises a rare clinical entity which can clinically manifest with the whole spectrum of thyroid disorders, including thyroid malignancy. Thyroid carcinoma arising in ectopic thyroid tissue is extremely rare, with only a few cases described in the literature so far. We present a very unusual case of a primary papillary thyroid carcinoma arising in a left lateral branchial cyst, describing our diagnostic and therapeutic approach for this uncommon clinical entity. This is the first case where recombinant thyrotropin was used along with radioiodine treatment in primary ectopic thyroid cancer.

Thoracic duct relationships to abnormal neurovascular structures in cervicothoracic regions: case study and clinical relevance

The presence of variant intercostal and bronchial arteries and variable position of left recurrent laryngeal nerve (LRLN) along the course of thoracic duct (TD) may have clinical relevance in various cervicothoracic surgeries.

Interrelationships between the innervations from the laryngeal nerves and the pharyngeal plexus to the inferior pharyngeal constrictor

PURPOSE

The inferior constrictor is innervated by the pharyngeal plexus and the external and recurrent laryngeal nerves. The communication between these nerves may influence the innervations. However, the relations of their anastomoses with the innervations have been unclear. This gross anatomical study re-examined the configuration of the inferior constrictor and investigated the variations of the anastomoses and the innervations of the constrictor to clarify their interrelationships.

METHODS

The inferior constrictor and the branches of the superior and recurrent laryngeal nerves and the pharyngeal plexus were examined under a binocular microscope in 30 Japanese cadavers.

RESULTS

The inferior constrictor consisted of the oblique fibers from the thyroid and cricoid cartilages and the horizontal ones from the cricoid. The oblique fibers were innervated by the pharyngeal plexus from the dorsal and ventral surfaces. The external laryngeal nerve gave twigs to the oblique fibers and the cricothyroid from the lateral surface. The recurrent laryngeal nerve supplied the horizontal fibers from the ventral surface. The internal laryngeal nerve sometimes and the main trunk of the superior laryngeal nerve rarely supplied the upper oblique fibers. The communicating branches between the laryngeal nerves and the pharyngeal plexus sometimes gave twigs to the constrictor from the dorsal surface.

CONCLUSIONS

The innervations to the inferior constrictor from the laryngeal nerves and the pharyngeal plexus are classified into some types based on their branching patterns and anastomoses, suggesting that the dysfunctions of the laryngopharyngeal region vary according to the positional relationships between the affected part and the innervations types.