Thyrohyoid Membrane Research Articles

Variations in the Origin of the Superior Laryngeal Artery and their Clinical Significance: A Case Report with a Proposal for a New Classification

The superior laryngeal artery is the primary vessel providing the blood supply to the larynx. Commonly, it is derived from the superior thyroid artery. Different variations in the origin have been described in the current literature; knowledge of such variations is crucial for various surgical interventions of the larynx and surgical procedures in the lateral region of the neck regarding the carotid triangle. It should be noted that radiological studies, such as selective angiography of the thyroid gland, can also be misleading in cases of variations. Herein, we describe a case of bilateral superior laryngeal artery originating directly from the external carotid artery of the neck. The arteries at first have a transverse course and then pierce through the thyrohyoid membrane alongside internal laryngeal nerves. Moreover, we also review the known variations in the origin of the superior laryngeal artery and propose a new classification of all known variations.

Thyroarytenoid botulinum toxin injection for refractory laryngeal contact granuloma

BackgroundAlthough there are many treatments for laryngeal contact granuloma (LCG), some patients still fail treatment. Botulinum toxin A injection vocal cords may be a salvage therapy. ObjectivesTo study the efficacy of thyroarytenoid botulinum toxin A injection for the treatment of refractory LCG. Material and methodsFrom May 2021 to March 2022, 23 male patients with refractory idiopathic LCG were treated by injection of botulinum toxin A into the thyroarytenoid muscle via the thyrohyoid membrane approach. Inspiratory-phase laryngoscopy images were collected before treatment and 3 months after injection treatment. The lesion size was evaluated with the Farwell granuloma endoscopic grading system and Image J software. ResultsThe average age of 23 patients was 49 years. The dose of botulinum toxin injection ranged from 2.5 to 5 units. Three months after injection, 17 patients were cured, 2 patients showed marked improvement, and 4 patients did not experience any effect. The total efficacy rate was 82.61% (19/23), and no serious complications occurred. Almost all patients experienced hoarseness within one week after injection; they gradually recovered after one month, and their voice returned to baseline at 3 months. ConclusionsThyroarytenoid botulinum toxin injection is an effective method for resolving refractory LCG.

Clinical anatomy of superior laryngeal artery via transoral approach.

ObjectiveHemorrhage is the most common complication caused by transoral laryngopharyngeal surgery. It is believed that proper management of the superior laryngeal artery (SLA), the main feeding artery for the larynx and pharynx, may reduce intra‐ and postoperative hemorrhage incidence. The aim of this study was to illustrate the anatomy of the SLA via transoral endoscopic approach.MethodsFourteen sides of SLA from heads of seven fresh‐frozen and silicone‐injected cadavers were dissected. Transoral dissections were performed for the intra‐laryngeal segment of SLA, and transcervical dissections were performed to confirm the anatomical measurements.ResultsSLA had a slightly descending course from the origin to the larynx, and there was a major branch supplying the epiglottis, named pharyngo‐epiglottic artery (PEA). Parallel with the internal superior laryngeal nerve (ISLN), SLA passed through the thyrohyoid membrane and ended into the hypopharynx. The distance from SLA to the superior horn of thyroid cartilage (SHTC) was (9.11 ± 0.58)mm on the left and (9.01 ± 0.37)mm on the right; the distance from SLA to the inferior margin of the hyoid bone (IMHB) was (2.00 ± 0.11)mm on the left and (1.95 ± 0.08)mm on the right; the distance from SLA to ISLN was (5.98 ± 0.48)mm on the left and (5.78 ± 0.36)mm on the right. No significant difference was found between bilateral sides (p > 0.05). Moreover, the distance from SLA to superior margin of thyroid cartilage (SMTC) was (5.52 ± 0.24)mm on the left and (5.80 ± 0.15)mm on the right. A significant difference was also found between bilateral sides (p = 0.03), which might suggest the SLA is located further from the SMTC on the right side.ConclusionSHTC, SMTC, and IMHB could be regarded as anatomical landmarks to locate SLA when applying a transoral approach. Moreover, a complete understanding of the detailed anatomy of the superior laryngeal artery may improve the detection of hemostasis in transoral laryngeal or hypo‐pharyngeal surgery.

Comparison of landmark-guided and ultrasound-guided technique for superior laryngeal nerve block to aid fibreoptic intubation - An observational study.

Awake fibreoptic intubation (AFOI) is the gold standard in the management of the difficult airway. Several methods to achieve airway anesthesia to aid AFOI include superior laryngeal nerve block (SLNB). This study aimed to compare land-mark-guided and ultrasound-guided techniques for SLNB to aid AFOI. This was a prospective, observational study. Patients in both groups received 1 mg Midazolam and 50 μg of fentanyl for mild sedation before intubation, nasal passages were anaesthetized using lignocaine-coated nasopharyngeal airways, nebulization of 3 ml of 2% lignocaine, and intratracheal injection of 2 ml of 2% lignocaine given through cricothyroid membrane. Patients in Group L received SNLB, at the lateral end of the thyrohyoid membrane (2 ml of 1.5% lignocaine). Patients in Group U had their thyrohyoid membrane visualized using linear ultrasound probe (8 - 13 Hz) and the injection was placed just superficial to the membrane using out of plane method. The groups were compared with respect to quality of anesthesia (assessed on a 5-point scale), patient comfort during AFOI, time taken to intubation and Haemodynamics. A total of 25 patients were enrolled: 13 in Group L and 12 patients in Group U. The demographics were comparable. Quality of airway anesthesia, time taken to intubation, haemodynamics and patient comfort were comparable. All were intubated successfully and there were no complications. USG-guided SLNB was comparable to landmark-based method with respect to quality of airway anesthesia and patient comfort. USG-guided block did not add any advantage over the landmark-based method.

Ultrasound Guided Measurement of Anterior Neck Tissue for the Prediction of Difficult Airway: A Prospective Observational Study.

To determine that ultrasound (US) measurements of anterior neck soft tissue thickness at hyoid bone, thyrohyoid membrane, and anterior commissure levels can be used to predict difficult laryngoscopy. The present study included 100 patients of age group 18-60 years undergoing elective surgery under general anaesthesia. It was a prospective observational study which included patients with ASA physical status I and II. Excluded patients were with facial and neck deformities, neck trauma, or those undergoing surgery of the larynx, epiglottis and pharynx. Comparison analysis was performed using t-test for continuous variables and chi-square or Fisher exact test for non-continuous variables. Correlation analysis performed using Pearson test. There were 39 out of 100 patients categorised as difficult laryngoscopy. Thickness at hyoid bone (DSHB), thyrohyoid membrane (DSEM) and anterior commissure (DSAC), MMS (modified Mallampati score), and BMI (body mass index) were greater in the difficult laryngoscopy group (p < 0.001). TMD (thyromental distance) was less in the difficult laryngoscopy group (p < 0.001). There was a strong positive correlation between DSEM and DSAC (r = 0.784). Moderate positive correlation was between DSEM and DSHB (r = 0.559), DSEM and MMS(r=0.437). The area under curve (AUC) of DSHB, DSEM, DSAC, TMD and MMS is >0.7. The optimal cut-off values for DSEM, DSHB, DSAC and TMD were 1.34 cm, 0.98 cm, 1.68 cm and 6.59 cm, respectively, in predicting difficult airway. Ultrasound measurement of soft tissue thickness at hyoid bone, thyrohyoid membrane, and anterior commissure of vocal cord are good independent predictors for difficult laryngoscopy. When combined with traditional screening tests it improves the ability to predict difficult laryngoscopy.

Pyramidal Lobe Nodule or Thyroglossal Duct Lesion? Approach to Diagnosis and Treatment

A 63-year-old woman presented with a 12-year history of an enlarging high anterior midline neck mass. Surgical history was notable for left hemithyroidectomy 17 years prior for multinodular hyperplasia. She reported intermittent globus sensation but was otherwise asymptomatic. Her examination demonstrated a midline neck mass overlying the thyrohyoid membrane that elevated with tongue protrusion (Fig. 1). Ultrasound showed a solid mass, isoechoic to the thyroid, with cyst components. Computed tomography imaging showed a 1.5 × 2.0 × 1.7–cm heterogeneous enhancing lesion with multiple nodules high in the midline (Fig.

Laryngeal spaces in the newborn larynx

ObjectivesDistributions of laryngeal spaces are important in understanding their functional significance. However, laryngeal spaces in the newborn larynx are enigmatic. MethodsFive normal human newborn larynges were investigated using whole organ serial section technique. ResultsThe chief newborn laryngeal spaces were the preepiglottic space, the paraglottic space and the cricoid area. They consisted of an areolar tissue area composed of brown adipose tissue (immature adipose tissue) and loose elastic and collagen fibers. The newborn preepiglottic space was immature and occupied a small area anterior to the epiglottis. The epiglottis lied on a somewhat horizontal axis and was partially obscured behind the hyoid bone. The hyoid bone overlapped the thyroid cartilage, partially obscuring the superior thyroid notch. The thyroid cartilage was present close to the hyoid bone and the thyrohyoid membrane ran between the superior surface of the thyroid lamina, and not the anteroinferior, but the posteroinferior surface of the hyoid bone. The preepiglottic space was located anterior, lateral and posterolateral to the thyroepiglottic ligament. However, the preepiglottic space was located anterior to the epiglottic cartilage. As seen in adults, the paraglottic space existed medial to the lamina of each bilateral thyroid cartilage. Each bilateral cricoid area was located along not only the superomedial but also the medial portion of the cricoid arch on both sides. ConclusionsAs the child grows, the preepiglottic space, occupying a small area anterior to the epiglottis, likely grows as the larynx descends and acquires the human adult vocal tract. From the functional histoanatomical point of view, the newborn laryngeal spaces appear to be favored for respiration and maintenance of a protective sphincter for the lower airway over phonation.

Comparative Study between two Ultrasound Aided Methods in PreoperativeAssessment of Difficult Airway in Obese Patients

Abstract Background Unpredictable difficult laryngoscopy remains a challenge for anaesthesiologists, especially if difficult ventilation occurs. So, accurate airway assessment should always be performed so as to provide appropriate planning and management of expected difficult intubation and to limit any unexpected difficulties. Airway assessment using ultrasound has been proposed recently as a useful, simple and non-invasive bed side tool as an adjunct to clinical methods. Objective To establish whether correlations existed between two ultrasound measurements and the Cormack–Lehane grade during direct laryngoscopy, and whether these measurements are useful in predicting are stricted or difficult view especially in morbid obese individuals. The first is the measurement of the hyomental distance of the patient in neutral position of the neck and in fully extended neck calculating the ratio between both of them. While the second is the measurement of anterior cervical soft tissue thickness at three anatomical levels (hyoid bone, thyrohyoid membrane or ‘pre epiglottic space’ and anterior commissure). We chose these two new measurements from among the various ultrasound assessments made in previous studies because of their simplicity of execution in normal clinical and in emergency settings. Patients and Methods The current study is a prospective comparative clinical trial of assessment of difficult air way using two different ultrasound aided techniques in comparison to Cormack and lehane scoring system. Those patients were chosen upon some inclusion and exclusion criteria; inclusion criteria were (Age of the patient (25-60y), ASA I-II patients, Obese patients with body mass index &amp;gt; 30 kg /m2 and Pts undergoing bariatric surgery) and exclusion criteria were (Pathology of the airway (tumors), Deformity of the airway anatomy (burns, scars), History of facial, cervical, pharyngeal and epiglottis surgery or trauma, Patients with most teeth lost and Patient refusal). Results Regarding U/S measurements in method A patients; the average HMD-neutral of A patients was (53.58±5.33) mm, the average HMD-extension was (58±7.82) mm, and the average HMDR was (1.07±0.06). It showed highly significant decrease in HMD extension and HMDR in difficult group, compared to easy group, in A group of patients (p &amp;lt; 0.01respectively). Non-significant difference as regards HMD-neutral U/S measurements in method A (p &amp;gt; 0.05). Conclusion Ultrasonography can be a valuable adjunct in this aspect of airway assessment. Ultrasound assessment of pre-epiglottic tissue thickness at the level of the thyrohyoid membrane may be useful to predict restricted/difficult direct laryngoscopy and difficult intubation. The ratio of hyomental distance between neutral and extended positions may also be a good predictor of difficult direct laryngoscopy.

The Superior Laryngeal Nerve and Its Vulnerability in Surgeries of the Neck.

Anatomical considerations of the superior laryngeal nerve (SLN), a branch of the vagus, provides information to minimize the potential for iatrogenic intraoperative injury, thereby preventing motor and sensory dysfunctions of the larynx. The present study aims to assess the variation of the SLN and its relationship to the superior thyroid artery (STA) and superior laryngeal artery (SLA). The study was done on 35 formalin-fixed cadavers at Oakland University in 2018–2019. In our study, we found that out of 21 cadavers, 52.4% of the external laryngeal branches (ebSLN) are related posteromedial to the STA, while 47.6% are related anteromedial to it. Out of 14 cadavers, 64.3% of the internal laryngeal branches (ibSLN) are related superoposterior to the SLA, while 35.7% are inferoposterior to it. In most cases, the SLA crosses above the ebSLN while traveling to pierce the thyrohyoid membrane to reach the larynx. The data demonstrate that both the ebSLN and ibSLN display variation in their relationship with the STA and the SLA, respectively. Awareness of these variable relationships is critical for identification and isolation of these structures in order to prevent consequences of nerve injury, primarily a reduction in the highest attainable frequency of the voice and aspiration pneumonia.

Early Internal Branch of Superior Laryngeal Nerve Bifurcation Passes Through Double Thyroid Foramen.

Internal branch of superior laryngeal nerve (ibSLN) provides sensory innervation mostly to the supraglottic part of the larynx and thus prevents aspiration during ingestion. Normally, it is distributed to the larynx after piercing the thyrohyoid membrane above the superior laryngeal artery. Multiple anatomical variations in the course of ibSLN have been reported. An early ibSLN bifurcation and course through double thyroid foramen constitutes an interesting anatomical variation that may easily lead to an injury during procedures in the thyroid gland and the larynx. Knowledge of the anatomical variability is essential in order to prevent surgical complications that could potentially impact the patient's quality of life.

Laryngeal Trauma

Introduction Laryngeal trauma can be an immediately life-threatening entity. Failure to recognize such injuries and delay in securing the airway may have fatal results. Early diagnosis and accurate evaluation with proper treatment is vital. Materials and Methods Fifteen patients with laryngotracheal injuries were analyzed prospectively. The outcome was assessed both in terms of voice and airway, on short term and long term basis. Result Commonest cause of injury was suicidal followed by road traffic accidents and strangulation. The main presenting symptoms and signs were stridor, hoarseness, haemoptysis and odynophagia. Five patients suffered penetrating trauma and ten patient sustained blunt trauma. Sites of laryngeal injury included; hyoid bone fracture, mixed soft tissue and cartilaginous injuries, thyrohyoid membrane and cricothyroid membrane injuries. Eleven patients presented within 24 hours of the injury. Outcome (airway and voice) was good in ten patients whereas it was poor in three patients. Poor results were seen in patients who had delayed surgical intervention. Conclusion Early surgical intervention is recommended for traumatic laryngeal injuries to ensure a good outcome; which further depends upon patient’s condition, injury and treatment-specific factors.

Local Triamcinolone Injection and Oral Steroid in the Patients with Thyrohyoid Syndrome

Background and Objectives Thyrohyoid syndrome is rare disease characterized by unilateral chronic neck pain on hyoid bone area. Currently, local triamcinolone injection was widely used, but oral steroid treatment was rarely tried. We compared the oral steroid and triamcinolone injection for the thyrohyoid syndrome. Subjects and Method Patients who had unilateral pain and tenderness at thyrohyoid membrane were enrolled while excluding those with other diseases, such as gastroesophageal reflux, by physical exam and history taking. Patients were treated with oral steroid (n=15) and local triamcinolone injection (n=11); pain scores based on the pretreatment and post-treatment numeric rating scale (NRS)-11 were compared between the groups.Results Patients with thyrohyoid syndrome were comorbid with globus (42.3%), sore throat (19.2%), and radiating pain (15.4%). In the oral steroid group, posttreatment pain scores (4.0± 2.2) significantly improved (p=0.001) more than pretreatment pain scores (7.7±1.2). In the triamcinolone injection group, posttreatment pain scores (2.3±1.7) also significantly improved (p=0.003) more than pretreatment scores (7.5±1.4). None of the patients revealed treatment related complications. Pretreatment scores were not significantly different, but post-treatment scores wre significantly better in the triamcinolone injection group than in the oral steroid group (p=0.047).Conclusion Oral steroid treatment could be easily performed and have significant effects for patients with thyrohyoid syndrome. Local triamcinolone injection was more effective than oral steroid treatment.

Transcutaneous Electrical Nerve Stimulation as a Treatment for Neuropathic Cough: A Tolerability and Feasibility Study.

Transcutaneous electrical nerve stimulation (TENS) is a form of electroanalgesia used for neuropathic pain disorders. Refractory chronic cough, or “neuropathic cough,” may be physiologically similar to other neuropathic pain conditions. This study explored the tolerability and feasibility of using TENS as a treatment for neuropathic cough. Laryngeal TENS was administered to five subjects with neuropathic cough. One electrode was placed over the lateral thyrohyoid membrane, and a second over the cricothyroid space. A frequency of 120 Hz was applied for 30 min. Participants rated symptoms pre-, during, and post-TENS treatment using a Likert scale. Laryngeal TENS was well tolerated by all subjects. Adverse effects included brief neck discomfort when increasing TENS intensity and an event of mild post-treatment hoarseness. The self-reported scores trended toward a reduction in symptom severity during and after treatment. Controlled trials using this method would elucidate the use of TENS for treatment of patients suffering from chronic cough.

Anterior neck soft tissue measurements on computed tomography to predict difficult laryngoscopy: a retrospective study

Predicting difficult laryngoscopy is an essential component of the airway management. We aimed to evaluate the use of anterior neck soft tissue measurements on computed tomography for predicting difficult laryngoscopy and to present a clear measurement protocol. In this retrospective study, 281 adult patients whose tracheas were intubated using a direct laryngoscope for thyroidectomy were enrolled. On computed tomography, the distances from the midpoint of the thyrohyoid membrane to the closest concave point of the vallecular (membrane-to-vallecula distance; dMV), and to the most distant point of the epiglottis (membrane-to-epiglottis distance; dME) were measured, respectively. The extended distances straight to the skin anterior from the dMV and dME were called the skin-to-vallecula distance (dSV) and skin-to-epiglottis distance (dSE), respectively. Difficult laryngoscopy was defined by a Cormack-Lehane grade of > 2. Difficult laryngoscopy occurred in 40 (14%) cases. Among four indices, the dMV showed the highest prediction ability for difficult laryngoscopy with an area under the receiver operating characteristic curve of 0.884 (95% confidence interval 0.841–0.919, P < 0.001). The optimal dMV cut-off value for predicting difficult laryngoscopy was 2.33 cm (sensitivity 75.0%; specificity 93.8%). The current study provides novel evidence that increased dMV is a potential predictive indicator of difficult laryngoscopy.

Comparison of Airway Ultrasound Indices and Clinical Assessment for the Prediction of Difficult Laryngoscopy in Elective Surgical Patients: A Prospective Observational Study.

Background:Ultrasound is evolving as a probable tool in airway assessment. The upper airway is a superficial structure and has sonographically identifiable structures which makes it ideal for evaluation with the ultrasound.Aims:The aim of this study was to evaluate the role of skin to hyoid and skin to thyrohyoid membrane distance in prediction of difficult laryngoscopy.Settings and Design:This is a prospective observational study included 150 patients aged 18–60 years of American Society of Anesthesiologists Physical Status I and II scheduled to undergo surgery under general anesthesia requiring laryngoscopy and endotracheal intubation.Materials and Methods:The modified Mallampati score, mouth opening, mentohyoid distance, thyromental distance were noted. Skin to hyoid bone distance and skin to thyrohyoid membrane distance were measured by ultrasound. Patients were clubbed retrospectively into easy and difficult laryngoscopy groups on the basis of Cormack Lehane grading, and the characteristics of both groups were compared.Statistical Analysis:Statistical Package for the Social Sciences, Version 23 was used for statistical analysis. Independent samples t-test was used to compare the means between difficult and easy laryngoscopy patients. Diagnostic accuracy of the significant (P < 0.05) variables between difficult and easy laryngoscopy patients was calculated using receiver operating characteristics curve in terms of their area under curve. Appropriate cutoff values (with corresponding sensitivity, specificity, and overall accuracy) were also identified.Results:Out of 150 patients, 13 (8.7%) were identified as difficult laryngoscopy whereas 137 patients (91.3%) were identified as easy laryngoscopy. The demographics of both groups were comparable. Mentohyoid distance, skin to hyoid bone distance, and skin to thyrohyoid distance were statistically different between easy and difficult laryngoscopy patients, with lower mentohyoid distance and higher skin to hyoid bone distance and skin to thyrohyoid distance in difficult laryngoscopy patients. Diagnostic accuracy of the mentohyoid distance (70.3%) was slightly superior to skin to hyoid bone distance (67.1%) and skin to thyrohyoid distance (68.1%).Conclusion:Ultrasound measurements of skin to hyoid bone and skin to thyrohyoid membrane distance fail to eclipse clinical parameters in accurately predicting a difficult laryngoscopy.

Diagnostic Accuracy of Ultrasound Measurements of Anterior Neck Soft Tissue in Determining a Difficult Airway.

Context:Airway management in the emergency department is challenging because conventional screening tools cannot be applied. Therefore, a rapid noninvasive means of identifying a difficult airway will be advantageous for emergency physicians.Aims:The aim of this study is to examine the association between ultrasound measurements of anterior neck soft tissue and difficult airway as judged by the Cormack Lehane grading.Settings and Design:A prospective study was done for 18 months on patients requiring intubation presenting to the emergency medicine department.Subjects and Methods:Ultrasound measurements of anterior neck soft tissue were obtained in 60 cases at the levels of thyrohyoid membrane, hyoid bone, and vocal cords. Another examiner who was blinded to the ultrasound measurements performed endotracheal intubation and noted Cormack–Lehane grading.Statistical Analysis Used:Descriptive statistics such as mean, standard deviation, frequency, and percentage were used. Inferential statistics such as Student's t-test and receiver operating characteristic (ROC) curve analysis were done using the SPSS software version 22.Results:The thickness of anterior neck soft tissues at the level of hyoid bone in difficult patients was 0.73 cm (95% confidence interval = 0.65–0.80) compared to easy patients 0.47 cm (95% confidence interval = 0.44–0.51) with a P = 0.001 and at the level of thyrohyoid membrane in difficult patients it was 1.83 cm (95% confidence interval = 1.7–1.89) compared to easy patients 1.46 cm (95% confidence interval = 1.41–1.51) with a P = 0.001. Area under the ROC curve was significant at all the three levels with the highest at the level of thyrohyoid membrane 0.99 and least at the level of vocal cords 0.79, the area under the curve was 0.92 at the level of hyoid bone.Conclusions:Sonographic measurements of the anterior neck soft tissue can be used as a screening tool by an emergency physician to detect difficult intubation.

Topographic anatomy of the ınternal branch of the superior laryngeal nerve.

The aim of this study was to investigate the surgical and topographical anatomy of the internal branch of the superior laryngeal nerve (ibSLN) in laryngectomy patients. Patients aged 36-90years old who underwent a total laryngectomy operation with a diagnosis of laryngeal carcinoma participated in the study. Fifteen patients who underwent a total laryngectomy operation between June 2015 and November 2016 were included in the study. A total of 29 superior laryngeal nerves (SLN) of 15 patients were studied. The position of the nerve was photographed before the thyrohyoid membrane (THM) was passed during dissection. The relationship and course of the ibSLN with respect to the superior laryngeal artery (SLA) were observed. The distance to adjacent formations and branching variants were examined along the course of the nerve. Of the total 29 ibSLN, 17 were divided into three branches and 12 into two branches. In all cases except for one, the ibSLN course after piercing the THM was determined. The ibSLN penetrated the THM at a mean of 12.0 ± 2.61mm (6-16mm) from the superior border of the thyroid cartilage. The ibSLN penetrated the THM with a mean distance of 9.34 ± 1.65 (6-12) mm from the inferior border of the hyoid bone. Our study demonstrated the surgical and topographical features of the ibSLN with respect to the THM, and provided a more precise knowledge of its anatomy in laryngectomy patients. It thus may help head and neck surgeons identify this nerve.

Validation of clinical versus ultrasound parameters in assessment of airway

Background & AimsEnsuring adequate ventilation and oxygenation requires comprehensive knowledge and specific skills to secure the airway. We hypothesized that airway assessment using ultrasound is superior in predicting difficult laryngoscopy and aimed to compare airway ultrasound with clinical assessment to predict it. MethodologyCross sectional study on 100 adults (65 females) undergoing elective surgeries with tracheal intubation in a tertiary centre were subjected to 2 staged airway assessment, both clinical and ultrasound. Airway ultrasound parameters recorded were anteroposterior thickness of geniohyoid muscle, distance from skin to hyoid bone, thyrohyoid membrane and true vocal cords. The Cormack and Lehane (CL) grade at laryngoscopy and Intubation Difficulty Scale (IDS) scores were noted. Results were analysed using Kappa statistics. ResultsNeck circumference and distance from skin to epiglottis at the level of thyrohyoid membrane (DSETM) were significant predictors of difficult laryngoscopy with a cut-off value of ≥35.8 cm (33% were predicted to be difficult however only 4% cases posed difficulty in laryngoscopy) and 1.9 ± 0.3 cm respectively. ConclusionAirway ultrasound is an objective and cost-effective modality in the anaesthesiologists’ armamentarium. DSETM ≥1.90 cm differentiated between easy and difficult laryngoscopy. Ultrasonography assessment adds an incremental diagnostic value to clinical screening tests.

Simplified four-step retropharyngeal approach for the upper cervical spine: technical note.

In this paper, we propose a simplified four-step retropharyngeal approach, whose aim is getting straight to the upper cervical spine minimizing complications. While the classical retropharyngeal approach includes about 11 steps, ours is a four-step approach: patient positioning, skin-platysma incision, hyoid bone superolateral dissection and retropharyngeal blunt exposure. We avoid several steps of the classical anterior retropharyngeal approach, particularly dissection of submandibular gland, facial veins, external carotid artery and thyroid artery, bellies of the digastric muscle, hypoglossal nerve, thyrohyoid membrane and the internal branch of superior laryngeal nerve. We have adopted this technique for five patients: two patients had a C2-C3 herniated disk with myelopathy, two patients had unstable Hangman fracture with no bone fusion after 2-month treatment with rigid collar, and one patient had a C2-C3 osteophyte with dysphagia. The intraoperative time needed for reaching the retropharyngeal space was 15 (first case), 9 (second case), 7min (third case-illustrative case-and fourth case), 8min (fifth case). No complications occurred. Our simplification, avoiding several steps, is simple, effective, safe, and rapid and requires a simple learning curve.

Effectiveness of four ultrasonographic parameters as predictors of difficult intubation in patients without anticipated difficult airway.

BackgroundPredicting difficult intubation (DI) is a key challenge, as no single clinical predictor is sufficiently valid to predict the outcome. We evaluated the effectiveness of four upper airway ultrasonographic parameters in predicting DI. The validity of the models using combinations of ultrasonography-based parameters was also investigated.MethodsThis prospective, observational, double-blinded cohort trial enrolled 1,043 surgical patients classified as American Society of Anesthesiologists physical status I–III without anticipated difficult airway. Preoperatively, their tongue thickness (TT), invisibility of hyoid bone (VH), and anterior neck soft tissue thickness from the skin to thyrohyoid membrane (ST) and hyoid bone (SH) were measured by sublingual and submandibular ultrasonography. The logistic regression, Youden index, and receiver operator characteristic analysis results were reported.ResultsOverall, 58 (5.6%) patients were classified as DI. The TT, SH, ST, and VH had accuracies of 78.4%, 85.0%, 84.7%, and 84.9%, respectively. The optimal values of TT, SH, and ST for predicting DI were > 5.8 cm (sensitivity: 84.5%, specificity: 78.1%, AUC: 0.880), > 1.4 cm (sensitivity: 81%, specificity: 85.2%, AUC: 0.898) and > 2.4 cm (sensitivity: 75.9%, specificity: 85.2%, AUC: 0.885) respectively. VH had a sensitivity and specificity of 72.4% and 85.6% (AUC: 0.790). The AUC values of the five models (with combinations of three or four parameters) ranged from 0.975–0.992. ST and VH had a significant impact on the individual models.ConclusionsSH had the best accuracy. Individual parameters showed limited validity. The model including all four parameters offered the best diagnostic value.