Surgical approach to the thyroarytenoid branch of the inferior laryngeal nerve through the thyroid cartilage

Observation of Anatomical Structures in the Human Larynx Using Micro-Computed Tomography with Lugol's Solution Enhancement

Histological and naked-eye dissections are frequently used to investigate human anatomy. However, limitations of conventional methods include tissue damage and difficulty in observing structures, rendering findings limited. Micro-computed tomography (micro-CT) allows for a three-dimensional observation with whole-mount staining for contrast enhancement. A precise anatomical understanding of the larynx is essential for both the medical and surgical fields; however, the larynx is difficult to dissect because of its minuscule and complex structures. Therefore, we aimed to clarify the detailed anatomy of the larynx using micro-CT. The study was conducted on twelve specimens of cadavers using Lugol-based-contrast micro-CT. Using Lugol-micro-CT, relevant information on human structures was obtained. Consequently, we successfully employed the Lugol-micro-CT technique in the analysis of specific human soft tissue structures that are challenging to analyze using conventional methods.

Isolated Paresis of Laryngeal Adduction: What Are the Laryngoscopic and Stroboscopic Findings?

OBJECTIVES/HYPOTHESIS

This study aimed to describe the videolaryngostroboscopic (VLS) findings in a cohort of patients with isolated paresis of laryngeal adduction and identify predictive variables that may be related to voice recovery.

STUDY DESIGN

Chart review and VLS analysis of dysphonic patients diagnosed with isolated paresis of laryngeal adduction by laryngeal electromyography (LEMG).

METHODS

Demographic, clinical, VLS, and LEMG findings were analyzed according to the outcome of dysphonia.

RESULTS

There were 17 patients, 12 males (70.6%), mean age of 46.6 years, with median dysphonia duration of 4 months (range, 1-60 months) included in the study. In all patients, gross movement of both vocal folds were normal. Laryngoscopy showed limited adduction of the ipsilateral ventricular fold, contralateral interarytenoid region deviation, and vocal fold atrophy in 100%, 94.1%, and 76.5% of patients, respectively. VLS findings included: impairment of glottic closure (94.1%), phase asymmetry (94.1%), and reduced mucosal wave on the affected side (76.5%). Predictors of good voice outcome were sudden onset (P = .012), duration of dysphonia on presentation shorter than 5 months (P = .005), and absence of polyphasic potentials on LEMG (P = .041).

CONCLUSIONS

Findings on VLS as described suggest isolated paresis of laryngeal adduction and should warrant indication of LEMG for definite diagnosis. Voice improvement may be related to clinical and LEMG findings.

LEVEL OF EVIDENCE

4 Laryngoscope, 129:919-925, 2019.

Development of Excised Larynx

The larynx is a complex organ which has a role in a variety of functions such as phonation, breathing, and swallowing. To research these functions, it is widely accepted that in vivo studies provide more anatomically and physiologically relevant findings. However, invasive procedures are generally needed to measure variables such a subglottal pressure, vocal fold tension and stiffness, and cricothyroid muscle stretch. Performing studies using excised larynges is a useful technique which makes it possible to not only measure phonation parameters but control them as well. Early studies using excised larynges mainly focused on controlling specific parameters and mathematical modeling simulations. The use of these studies has helped further research in laryngeal anatomy, imaging techniques, as well as aerodynamic, acoustic, and biomechanical properties. Here, we describe the progress of this research over the past 5 years. The number of accepted animal models has increased and ideas from excised larynx studies are starting to be applied to treatment methods for laryngeal disorders. These experiments are only valid for an excised situation and must continue to be combined with animal experimentation and clinical observations.