Bedside preoperative predictors of difficult laryngeal exposure in microlaryngeal surgery

PURPOSE

Successful microlaryngeal surgery relies on an adequate laryngeal exposure. Recognizing the likelihood of challenging exposure prior to microlaryngeal surgery may assist in selecting the appropriate surgical approach and even prompt consideration of alternative treatment options. We aim to apply the mini-Laryngoscore, a preoperative assessment tool, to our study population and incorporate novel variables to optimize the prediction model.

METHODS

This single-center prospective cohort study included 80 consecutive patients undergoing elective microlaryngeal surgery, from January 1, to June 30, 2023. Each patient underwent a presurgical evaluation of 15 parameters and an intraoperative scoring of the anterior commissure visualization. These parameters were assessed for their association with difficult laryngeal exposure, using multiple logistic regression analysis. We created a novel prediction model for DLE and compared it with the existing model, the mini-Laryngoscore.

RESULTS

Out of 80 patients, 24 (30%) patients had difficult laryngeal exposure, including 3 cases (3.8%) in which visualization of the anterior commissure was not possible. A large neck diameter (OR, 1.4; CI 1.1-1.9) and the presence of upper teeth (OR, 8.9; CI 1.3-62.8) were independent risk factors for a difficult laryngeal exposure, while a larger interincisors gap was the only independent protector factor (OR, 0.3; CI 0.1-0.8). The logistic regression model combining these three independent risk factors displayed a high discriminative value AUC = 0.89 (CI 0.81-0.97). The predictive performance of the mini-Laryngoscore was 0.73 (CI 0.62-0.85).

CONCLUSION

Combining two parameters from the mini-Laryngoscore (upper jaw dental state and interincisors gap distance) with neck circumference measurement can accurately predict the risk of difficult laryngeal exposure.

Assessment of Preoperative Predictors for Difficult Laryngeal Exposure in Endolaryngeal Surgery

Introduction

The proper visualisation of the larynx is required for the diagnostic assessment and therapeutic intervention. The most significant challenges for surgeon is to visualise the anterior commissure of the glottis region. The aim of this study is to record the preoperative laryngoscore in patients posted for endolaryngeal surgery and to assess preoperative predictors for intraoperative difficult laryngeal exposure by correlating with preoperative laryngoscore.

Design

Prospective, Cross-sectional, Observational study.

Setting

Department of Otorhinolaryngology in a tertiary care teaching facility.

Subjects

150 patients were included with an endolaryngeal disease who were planned for surgery with age > 18yrs.

Methodology

In 150 subjects preoperative laryngoscore was calculated, which comprised 11 parameters including thyromental distance, mandibular prognathism, macroglossia, micrognathia, trismus, inter incisor gap, degree of neck flexion-extension, history of prior open-neck surgery or radiotherapy, upper jaw dental status, modified Mallampati score and body mass index in order to produce a total score out of a possible maximum score of 17. According to the anterior commissure visualisation all patients were categorised into five classes, ranging from class 0 to class IV during surgery. The laryngoscore parameters were assessed and compared statistically with five classes of intraoperative anterior commissure visualisation.

Result

Out of 150 patients 70 (46.6%) were having 3-4 laryngoscore, followed by 45 (30%) patients with 5-6 laryngoscore. Total 123 (82%) patient had class 0,1 and 2 intraoperative anterior commissure visualisation while 27 (18%) had class 3 and 4 visualisation. If laryngoscore was either less or equal to 5, 90% of the patients had excellent laryngeal exposure whereas only 10% of the patients had challenging laryngeal exposure. At univariate analysis, thyromental distance, degree of neck flexion/extension, and modified Mallampati classification were found statistically significant for difficulty of anterior commissure visualisation independently.

Conclusion

A sound, easy and valid preoperative laryngoscore may be significantly helpful in identifying intraoperative difficult laryngeal exposure. This may prevent inadequacy of surgery, abandon of surgery, intra operative complication, and medico-legal cases for laryngologist.

A Prospective Study to Correlate Difficult Intubation with Difficult Laryngeal Exposure for Microlaryngeal Surgery using Various Grading Scales of Difficult Intubation

Adequate visualization of the vocal folds is essential for optimal phonosurgery. Pre-operative knowledge of a difficult laryngeal exposure (DLE) can alert the surgeon regarding the need for alternative measures. Our study is based on the hypothesis that a patient who has difficult intubation (DI) is likely to have DLE, thus scales anticipating DI should also anticipate DLE. Our aims were to correlate patients of actual DI on table with patients who had DLE, secondly to assess the ability of grading scales of DI to predict DLE and finally to obtain a cut-off value of neck circumference and length for predicting DLE. This is a prospective, observational study wherein four grading scales; Modified Mallampati Classification (MMC), 3-3-2, Upper lip bite test (ULBT) and Neck Mobility (NM) were used for anticipating DI and correlated with DLE during MLS. Occurrence of actual DI and DLE was correlated. Neck circumference and neck length was correlated with incidence of DLE. Out of 42 patients, 22 were anticipated to have DI (52.38%). Actual incidence of DI was 6 (14.28%) and DLE was 10 (23.80%). Correlation between actual DI and DLE was statistically significant. Of the 4 grading scales, ULBT was significant in predicting DLE. Neck circumference more than 37.5 cm and neck length less than 15.3 cm was significant in anticipating DLE. There is a significant correlation between DI and DLE. A positive ULBT, neck circumference more than 37.5 cms and neck length less than 15.3 cms are independently suggestive of a DLE.

Sternum-mental angle: A new predictor of difficult. Laryngeal exposure in suspension microsurgery - An observational study

OBJECTIVES

In our study, we hypothesized that sternum-mental angle (SMA) was a totally new preoperative predictor of difficult laryngeal exposure (DLE). The main objective of this study was to evaluate the diagnostic utility of SMA in predicting DLE in patients undergoing suspension microlaryngeal surgery, and we also searched for risk factors among the selected parameters.

METHODS

A total of 95 patients with vocal cord dysfunction who underwent microlaryngeal surgery were collected. According to the Cormack-Lehane classification method, the patients were divided into non-DLE group (n=73) and DLE group (n=22). Preoperative assessments included age, sex, body mass index (BMI), Modified Mallampati's index (MMI), neck circumference (NC), thyroid-mental distance at neutral position (TMD-NP), TMD at full extension position (TMD-FE), sternum-mental distance at neutral position (SMD-NP), SMD at full extension position (SMD-FE), SMA at neutral position (SMA-NP) and SMA at full extension position (SMA-FE). SMA was defined as the angle between the horizontal line and the line from upper border of the manubrium sterni to mental prominence, and SMA's ability to predict difficult laryngoscopy was compared with that of established predictors.

RESULTS

The DLE incidence of the enrolled patients was 23%. Univariate analysis showed that patients in DLE group presented significantly smaller SMA values. SMA-NP less than 13 provided 68.2% sensitivity and 83.6% specificity and SMA-FE less than 22.5 provided 86.4% sensitivity and 80.8% specificity for the detection of DLE. SMA-FE (≤22.5) exhibited the largest area under the curve (AUC: 0.868; 95% CI: 0.784-0.952), confirming its better predictive ability. Binary multivariate logistic regression analyses identified four risk factors including MMI, TMD-FE, TMD-NP which were independently associated with DLE.

CONCLUSIONS

SMA is a new and simple predictor with a higher level of efficacy, and could help otorhinolaryngologist plan for managements in patients with DLE.

A Study of Application of Preoperative Clinical Predictors of Difficult Laryngeal Exposure for Microlaryngoscopy: The Laryngoscore in the Indian Population

Good exposure for visualisation of the glottis is an essential prerequisite for effective microlaryngoscopy. There is no definitive clinical predictor scoring system to predict difficult microlaryngoscopy. The aim of the study was to study the validity of the Laryngoscore scoring system as a preoperative clinical predictor score in Indian population for difficult laryngeal exposure during microlaryngoscopy. A prospective study was carried out in 32 patients undergoing microlaryngoscopy in a tertiary care hospital who were evaluated by a standardized preoperative assessment protocol (Laryngoscore) which included 11 parameters interincisors gap, thyro-mental distance, upper jaw dental status, trismus, mandibular prognathism, macroglossia, micrognathia, degree of neck flexion-extension, history of previous open-neck and/or radiotherapy, Mallampati's modified score, and body mass index. Each parameter was assessed to obtain a total score (Maximum-17). Patients were divided into five classes according to the anterior commissure visualization: class 0 to class IV. Class 0 being complete and class IV being impossible AC visualization. When the Laryngoscore was < 6, good laryngeal exposure was observed in 94% of patients. Laryngoscore had a sensitivity of 87.5% and specificity of 75% in predicting difficult laryngeal exposure. The positive and negative predictive values of the same are 53.8% and 94.7% respectively. Our study found that the Laryngoscore scoring system as a preoperative indicator for predictor of Difficult Laryngeal Exposure during Micro Laryngeal surgeries is very useful in the Indian population.

Management of Difficult Laryngeal Exposure During Suspension Microlaryngoscopy

Difficult laryngeal exposure during suspension microlaryngoscopic surgeries is a common situation encountered by the phonosurgeons nowadays. It leads to unnecessary trauma, incomplete surgery and even abortion of the procedure. Although various methods have been described to counter the situation, they might not be adequate in some cases with very anteriorly placed larynx. This study is intended to determine the utility of angled rigid endoscope along with malleable endoscopic instruments to improve surgical access in cases with inadequate glottic exposure during suspension microlaryngoscopy. In this cross sectional study conducted at Lokmanya Tilak Municipal Medical College and General Hospital in Mumbai, 50 patients of voice disorders who underwent Suspension Microlaryngoscopy from July 2014 to December 2017 were included. Out of these patients, 5 patients (10%) presented with difficult laryngeal exposure that were operated using readily available angled rigid endoscope along with malleable endoscopic instruments, without requirement of any specially designed instruments. There was improvement in laryngeal exposure in all the cases following utilisation of angled endoscopes. The surgeries were carried out under video monitor guidance with complete excision of the vocal cord lesions. Our study concluded that the cases in which the laryngeal exposure cannot be improved even by various external procedures, can be enhanced by application of angled rigid endoscopes and the vocal cord lesions can be excised completely by using malleable endoscopic instruments.

Analysis of Pressure Distribution During Direct Microlaryngoscopy

OBJECTIVE

This study aimed to investigate the pressure distribution during direct microlaryngoscopy and its relation with the positioning of the patient.

STUDY DESIGN

This is a prospective study in cadavers.

MATERIALS AND METHODS

The pressure distribution during direct microlaryngoscopy was investigated in five adult fresh cadavers by using matrix-based piezoresistive thin-film sensors. The pressure among three head and neck positions (extension-extension, neutral, and flexion-extension) was studied.

RESULTS

The real-time pressure and its distribution were recorded as 3-D contours. The map commonly showed two peak pressure points, with one focused on the middle of the laryngoscope (peak pressure 1) and the other one focused on the distal part of the laryngoscope (peak pressure 2). The mean average pressure in this study was 38 ± 13 kPa, and the flexion-extension position had the lowest average pressure and peak pressure. However, the average pressure and peak pressure 1 showed no significant difference among the three positions (P > 0.05); peak pressure 2 in the flexion-extension position was significantly lower than that in the extension-extension position (P = 0.024) and the neutral position (P = 0.020).

CONCLUSIONS

The results of this study indicate that the flexion-extension position induced lower pressure exerted on the laryngoscope and is an optimal position for direct microlaryngoscopy. Hyoid bone may play an important role in the pressure exerted.

Preoperative clinical predictors of difficult laryngeal exposure for microlaryngoscopy: the Laryngoscore

OBJECTIVES/HYPOTHESIS

To identify a clinical predictor score for difficult laryngeal exposure (DLE) during operative microlaryngoscopy.

STUDY DESIGN

Prospective cohort study in two academic institutions.

METHODS

We evaluated 319 patients before microlaryngoscopy for benign and malignant glottic diseases by a standardized preoperative assessment protocol (Laryngoscore) that included 11 parameters: interincisors gap (IIG), thyro-mental distance, upper jaw dental status, trismus, mandibular prognathism, macroglossia, micrognathia, degree of neck flexion-extension, history of previous open-neck and/or radiotherapy, Mallampati's modified score, and body mass index (BMI). Each parameter was assessed to obtain a total score. Patients were divided into five classes according to the anterior commissure (AC) visualization: class 0, complete AC visualization with large-bore laryngoscopes in the Boyce-Jackson position; class I, as class 0 with external laryngeal counterpressure; class II, as class I in the flexion-flexion position; class III, as class II using small-bore laryngoscopes; and class IV, impossible AC visualization.

RESULTS

Class 0-I-II (good/acceptable laryngeal exposure) presented a median score < 6. This value was chosen as cutoff for distinguishing favorable versus difficult/impossible laryngeal exposures. When the Laryngoscore was < 6, good laryngeal exposure was observed in 94% of patients, whereas when ≥ 6, DLE was encountered in 40%. When considering a Laryngoscore of ≥ 9, 67% of patients had a DLE. At univariate analysis, IIG, upper jaw dental status, macroglossia, micrognathia, degree of neck flexion-extension, and BMI statistically impacted on DLE (P < 0.05).

CONCLUSIONS

The Laryngoscore is a good predictor of DLE and assists in selecting the ideal candidates for operative microlaryngoscopy.

LEVEL OF EVIDENCE

2b.