Sectional anatomy of the larynx: implications for the transcutaneous approach to endolaryngeal structures

A new and clinically symptomatic variant of thyroid cartilage anatomy

We present a previously undescribed variation in the anatomy of the superior cornu of the thyroid cartilage. In the five cases described, the tip of the cornu turned medially and caused an indentation into the pharynx. These indentations were symptomatic and caused pain and globus sensation. Resection of them led to resolution of the symptoms. A survey of the incidence of this variation of the thyroid cartilage in a clinic population is presented.

Management of unilateral vocal cord paralysis by injection medialization with teflon paste. Quantitative results

This paper prospectively analyzes eight patients who were selected for injection medialization of a unilateral vocal cord paralysis by a transcutaneous technique. Preoperative and postoperative videolaryngoscopic recordings of the position of the paralyzed cord were made with a scoring system correlated to the laryngeal airflow measurements. Quantitative acoustic recordings of the patient's voice were also taken and compared with the patient's own subjective analysis of his or her voice. Results indicate that Teflon injection by the transcutaneous method gives a statistically and clinically improved voice in the short term.

[Presymptomatic injury of the recurrent laryngeal nerve in benign thyroid disease: contribution of electromyography]

Diagnosis of recurrent laryngeal nerve palsy is usually possible through a clinical, laryngoscopical and electromyographical approach, but at a critical stage of the nerve injury. We observed four cases of benign thyroïd tumoral processes with a preoperative electromyographic examination showing neurogenic abnormalities in the thyroarytenoid muscle without any clinical symptoms. We presume that only laryngeal electromyography permits the diagnosis of mild, even asymptomatic laryngeal recurrent nerve injury. A recurrent laryngeal nerve palsy occurs in thyroid tumors, most often in malignant conditions, rarely in benign ones. Nevertheless early forms of nerve injury with benign thyroïd pathology could be underrated. Since the functional prognosis of symptomatic laryngeal nerve palsy is doubtful, laryngeal electromyography, through its ability to diagnose early nerve injury, provides helpful indications in thyroïd benign tumoral diseases for the therapeutic decision.

Morphometry of the larynx in horizontal sections

PURPOSE

Until recently, only few studies on laryngeal morphometry in the horizontal plane, which used unreliable techniques, have been reported. The established methods of whole-organ serial sectioning of the larynx serve the purpose of histological investigation very well. Because they cause major tissue shrinkage, these techniques are not useful for morphometry. Nevertheless, normal data of laryngeal horizontal anatomy are of great surgical and diagnostic interest. Data on endolaryngeal angles, airway lumina, and the thickness of parts of the laryngeal skeleton can be helpful in the planning of endolaryngeal surgical intervention or the transcutaneous placement of electrodes for laryngeal electromyography. The aim of this study was to establish a method for the production of whole-organ serial sections that allows for the collection of exact and reliable morphometrical data.

MATERIALS AND METHODS

A total of 20 fresh human cadaver larynges were investigated in this study. Nineteen measurements on three different planes were obtained in each larynx. The larynges were shock-frosted using liquid propane and nitrogen and then cut with a slicing machine. Measurements were obtained using a computer-aided analyzing system.

RESULTS

The collected data give an exact and extensive description of the morphometrics of laryngeal structures such as thyroid and cricoid cartilage, arytenoid cartilages, vocal cords, and endolaryngeal airways at different section levels.

CONCLUSION

This study is the first to provide detailed anthropometric data on whole-organ sections of the larynx following a new method. This technique of using serial sections of the investigated specimen avoids artifacts caused by tissue fixation. Thus, it may be considered being particularly suited to the conduction of anthropometric studies on human larynges.

Dimensions of the laryngeal framework in adults

The increasing application of sophisticated electrophysiological, radiological and surgical methods to the diagnosis and treatment of laryngeal disorders requires a profound knowledge of the size and proportions of the human larynx and it's cartilaginous components. Only inadequate data regarding this subject have so far been accessible. The larynges of 53 patients (28 male and 25 female, age 25-88 years, in the means 59 years) were removed during routine autopsy 12-48 h post mortem and immediately submitted to morphometric investigation. None of the patients had histories or visible signs of laryngeal disease. Anatomical preparations were performed with customary surgical tools and morphometric measurements then carried out with a pair of compasses and a calliper rule. A total of 95 measurements were performed on each larynx. These included, aside from evaluation of the whole organ, identification of the internal and external diameters of the cricoid cartilage, height and length of the thyroid alae in different planes, angle of thyroid laminae, height of arytenoid cartilage, width and length of epiglottic cartilage, and internal and external diameter of first tracheal ring. The results obtained provide a full scale of data determining the size and extent not only of it's cartilaginous components, but of the laryngeal framework as a whole. The knowledge of these data may contribute to a precise positioning of electrodes in laryngeal electromyography, to the planning of laryngeal framework surgery, and to the analysis of CT- and MRI-scans of the larynx.

Transcutaneous Teflon injection for vocal cord paralysis

In 1989, I reported a series of 19 cases of unilateral vocal cord paralysis treated by transcutaneous Teflon injection. At that time it was shown that unilateral vocal cord paralysis could be effectively treated in the office in the unanesthetized patient using a transcutaneous route of injection. Since that time, an additional 43 patients have been treated using a similar technique. The initial impression of safety and efficacy has been confirmed in this subsequent series. Several refinements in this technique have simplified its use and improved its reliability. No airway complications have been observed to date and no patients have required hospital admission. Transcutaneous Teflon injection can be considered a useful method for treatment of vocal cord paralysis in selected patients.

Intraoperative laryngeal electromyographic assessment of patients with immobile vocal fold

The differential diagnosis of laryngeal ankylosis versus paralysis is occasionally difficult in patients with immobile vocal folds. Eight patients with acute and chronic evidence of vocal fold immobility were investigated by intraoperative electromyography (IEMG) during planned microlaryngoscopy. Bipolar hook wire electrodes were inserted into the thyroarytenoid muscle, of which the electrical activity was monitored during neuromotor blockade and emergence from anesthesia. The normal side and the side with ankylosis or stenosis showed normal IEMG activity. There was progressive recruitment of larger motor units during recovery from muscle relaxation. Patients with laryngeal paralysis failed to show such recruitment patterns. Thus, IEMG can be used as a diagnostic tool during operative laryngoscopy to differentiate neuromotor injury from anatomic causes of vocal fold immobility. The advantages of IEMG are its ease of application and certainty of electrode position. It can also be used to monitor recurrent nerve integrity and detect early laryngospasm. Further IEMG clinical study is warranted.