Mandibular tori as a cause of inability to visualize the larynx

Mandibular Tori Limiting Treatment of Carcinoma of the Upper Aerodigestive Tract

Background:

Mandibular tori are a rare cause of difficult direct visualization of the upper aerodigestive tract. In the setting of aerodigestive tract pathology necessitating direct visualization, removal of mandibular tori may be required to facilitate treatment.

Methods:

In the first case, large bilateral symmetric mandibular tori were removed to facilitate access to the anterior commissure and removal of a T1 glottic squamous cell carcinoma (SCC). In the second case, large bilateral mandibular tori were removed to access a markedly exophytic SCC in the right vallecula. Subsequently, the tumor was removed with robotic assistance with excellent exposure.

Results:

Both patients were free of recurrence at last follow-up.

Conclusion:

Mandibular tori are an uncommon cause of difficult direct laryngoscopy. In situations that require direct visualization of the anterior commissure or base of tongue for diagnosis and management of lesions, surgical removal of the tori may be required as in the cases presented here.

Effect of Mandibular Tori on Glottic Exposure During Simulated Suspension Microlaryngoscopy

Objectives:

Mandibular tori have been identified as a contributing factor in difficult exposure during intubation. However, no investigation has measured the effect of mandibular tori on glottic exposure during suspension microlaryngoscopy (SML). The objective of this study was to measure how the size and location of mandibular tori affect glottic exposure during simulated SML at different thyromental distances.

Methods:

Suspension microlaryngoscopy was modeled on an anatomically accurate skull and larynx with thyromental distances between 6 and 12 cm. Mandibular tori were simulated by protruding screws 5 to 15 mm from the lingual aspect of the mandible. The tori were positioned either 15 mm (anterior) or 25 mm (posterior) from the midline of the symphysis. The glottic exposure for the various-size tori in each location was measured by recording the displacement of the glottiscope tip relative to the most anterior exposure achievable without tori. The glottiscope angle relative to the horizontal plane was measured for each condition.

Results:

Mandibular tori of more than 10 mm had a significant impact on glottic exposure. Displacement of the glottiscope tip ranged from 2 to 9 mm for anteriorly placed tori and from 7 to 29 mm for posteriorly placed tori, with larger tori causing greater displacement. Increasing the thyromental distance increased the posterior glottiscope tip displacement regardless of torus size or location. The glottiscope angle increased with larger tori (12º to 28º), but this angle did not change with increasing thyromental distance.

Conclusions:

Larger size and more-posterior location of mandibular tori more significantly reduce glottic exposure during SML. The inner table of the mandible is the most relevant anatomic constraint on glottic exposure, which varies with the presence or absence of mandibular tori independent of thyromental distance.

Assessment of difficult laryngoscopy by electronically measured maxillo-pharyngeal angle on lateral cervical radiograph: A prospective study

Background:

Difficult airway continued to be a major cause of anesthesia-related morbidity and mortality. Successful airway management depends on direct laryngoscopy and tracheal intubation. Difficult laryngoscopy is a resultant of incomplete structural arrangements during the process of head positioning. Through clinical history, examination of the patients along with craniofacial indices alerts the anesthetist for difficult laryngoscopy. But it does not predict all causes of difficult laryngoscopy during pre-anesthetic evaluation. The maxillo-pharyngeal angle, an upper airway anatomical balance, was proposed for better understanding the pathophysiology of difficult laryngoscopy. In our study we have assess difficult laryngoscopy by electronically measuring maxillo-pharyngeal angles on a lateral cervical radiograph. This angle is normally greater than 100°. Less than 90° angle suggests either impossible or difficult direct laryngoscopy when all known craniofacial indices were within the normal range. Cervical radiographic assessment is a simple, economical, and non-invasive predictive method for difficult laryngoscopy. It should be used routinely along with other indices as pre-anesthetic airway assessment criteria to predict the difficult laryngoscopy.

Context:

Difficulties with airway management continue to be a major cause of anesthesia-related morbidity, mortality, and litigation. Pre-operative assessment of difficult laryngoscopy by the simple and non-invasive radiological method can help to prevent them.

Aims:

To assess the difficult laryngoscopy pre operatively by a simple and non invasive radiological method by electronically measuring maxillo-pharyngeal angle on a lateral cervical radiograph and it’s correlation with Cormack and Lehane grading.

Settings and Design:

This is a controlled, nonrandomized, prospective, cohort observation study.

Patients and Methods:

The 157 adult consented patients of ASA grade I to III of either sex, scheduled for elective surgery under general anesthesia with endo-tracheal intubation, were studied. The patients with identified difficult airway indices were excluded from the study. The maxillo-pharyngeal angle was electronically measured on a lateral cervical radiograph and was correlated with ease or difficulty of laryngoscopy under general anesthesia. Their degree of laryngeal exposure according to Cormack and Lehane classification grade was also noted.

Statistical Analysis used:

We performed univariate analyses to evaluate the association between the covariates and direct laryngoscopy.

Results:

In 148 patients (94.28%), the maxillo-pharyngeal angle was more than 100°, in 7 patients (4.45%) it was less than 90°, and in 2 patients (1.27%) the M-P angle was less than 85° with normal craniofacial indices. When the MP angle was less than 90°, the direct laryngoscopy was difficult which could be compared with to Cormack and Lehane classification grade III and IV.

Conclusions:

Lateral cervical radiographic assessment should be used as pre-anesthetic airway assessment criteria to predict the difficult laryngoscopy as it is a simple, safe and non-invasive method.