Dennis M. Moore

Laryngeal modeling: theoretical, in vitro, in vivo.

Because the larynx is situated anatomically in an area which is difficult to measure and visualize, theoretical, in vitro, and in vivo models are used in laryngeal research. Vocal fold vibration was studied in anesthetized dogs, while electrically stimulating independently the superior and recurrent laryngeal nerves under conditions of constant airflow. Photoglottographic (PGG), electroglottographic (EGG), and subglottic pressure signals were obtained while stroboscopically photographing the larynx. Specific points along PGG, EGG, and subglottic pressure waveforms were correlated with laryngeal events which occurred during vibration. The canine larynx, in an experimentally produced phonatory mode, vibrates in a two mass (upper and lower margin) system and appears comparable to modal human voice production. The recorded glottogrophic waveforms from experimentally produced phonation in the canine are similar to signals recorded from humans. However, observed differences can be related to anatomic differences.

The effect of laryngeal nerve stimulation on phonation: a glottographic study using an in vivo canine model.

The present investigation was designed to examine the effect of change in vocal fold mass and stiffness on vocal fold vibration. To do this, the effect of variation in superior laryngeal nerve stimulation (SLNS) and recurrent laryngeal nerve stimulation (RLNS) was studied Photoglottography (PGG), electroglottography (EGG), and subglottic pressure (Psub) were measured in seven mongrel dogs using an in vivo canine model of phonation. The PGG, EGG, and Psub signals were examined at three frequencies (100, 130, and 160 Hz) for SLNS and RLNS, using a constant rate of air flow. Increasing SLNS, which caused a contraction of the cricothyroid muscle, produced a marked increase in F0, little change in Psub, an increase in open quotient (OQ), and a decrease in the closed quotient (CQ) of the glottal cycle. Increasing RLNS, which caused activation of the intrinsic laryngeal muscles, produced a modest increase in F0, a marked increase in Psub, no change in the OQ, and an increase in CQ. Phase quotient (Qp), which describes the interval between opening of the lower and upper fold margins, decreased with increasing RLNS and did not change significantly with increasing SLNS. Based upon changes in F0, Psub, OQ, CQ, and Qp, SLNS provides a physiologic correlate of the tension parameter Q, and RLNS provides a physiologic correlate of the parameter Psub in the Ishizaka and Flanagan two-mass model.

Videostroboscopy of the canine larynx: The effects of asymmetric laryngeal tension†‡

The effects of simulated paralysis of the peripheral laryngeal nerves on patterns of vocal cord vibrations were studied. Videostroboscopy was used in seven anesthetized mongrel dogs to record laryngeal vibrations during direct electrical stimulation of the recurrent and superior laryngeal nerves under conditions of constant airflow. Stroboscopic images obtained from both supraglottic and subglottic aspects were analyzed frame‐by‐frame. Results indicated that simulated paralysis of the recurrent laryngeal nerve or combined paralysis of the recurrent and superior laryngeal nerves produced a diminished mucosal wave bilaterally, with loss of the two‐mass system of vibration and diminished lateral excursion of the normal cord. In contrast, simulated paralysis of the superior laryngeal nerve was characterized by an abnormally exaggerated vertical movement of the paralyzed cord in relation to the normal cord and a horizontal shifting of the glottis from the paralyzed to the normal side during each vibratory cycle. Clinical implications are discussed and the literature reviewed.

A preliminary study of particle velocity during phonation in an in vivo canine model

Summary The particle velocity across the glottis was measured with simultaneous electroglottography, photoglottography, and subglottic pressure in an in vivo canine model of phonation. A constant temperature anemometer measured flow velocity at five midline anterior to posterior glottal positions. Tracheal input air flow was varied in five steps from 175 to 500 cc/s, while vocal fold approximation was achieved by constant electrical stimulation of the laryngeal nerves. For all levels of air flow, a decreasing peak velocity gradient was observed from the anterior commissure to the arytenoids. Time-varying features of the flow velocity are discussed in relation to glottal vibratory events and aerodynamics.

Effect of superior laryngeal nerve stimulation on phonation in an in vivo canine model

We investigated the effect of variation in superior laryngeal nerve stimulation (SLNS) on vocal fold vibration. Photoglottography (PGG), electroglottography (EGG), and subglottic pressure (Psub) were measured in seven mongrel dogs using an in vivo canine model of phonation. The PGG, EGG, and Psub signals were examined at three SLNS frequencies (100 Hz, 130 Hz, and 160 Hz) using a constant rate of air flow. Increasing SLNS, which causes a contraction of the cricothyroid muscle, produced a marked increase in Fo, little change in Psub, an increase in the open quotient, and a decrease in the closed quotient of the glottal cycle.

Cancer of the Tongue Base Treated by a Transpharyngeal Approach

Tongue base resection plays an important role in the management of the patient with cancer of the posterior tongue. The considerable morbidity resulting from loss of functional tongue includes compromised deglutition, chronic aspiration, and altered speech articulation. The particular operative approach used dictates additional secondary morbidity, which may include cosmetic and functional defects of the mandibular arch, malocclusion, lip and chin scars, and postoperative changes in the oral cavity. Our recent experience with a transpharyngeal approach in 13 patients with tongue base cancer is reviewed. Adequate operative exposure was obtained in all cases. Persistent aspiration was not a problem, and all patients learned to swallow effectively. The transpharyngeal approach avoids unnecessary surgical trauma to the mandible and anterior oral cavity and minimizes cosmetic deformity. Our early experience with this approach is encouraging.

The effect of recurrent laryngeal nerve stimulation on phonation in an in vivo canine model.

The present investigation was designed to examine the effect of variation in recurrent laryngeal nerve stimulation (RLNS) on vocal fold vibration. Photoglottography (PGG), electroglottog‐raphy (EGG), and subglottic pressure (Psub) were measured in seven mongrel dogs using an in vivo canine model of phonation. The PGG, EGG, and Psub signals were examined at three fundamental frequencies (F0) (100 Hz, 130 Hz, and 160 Hz) for RLNS, using a constant rate of air flow. Increasing RLNS, which caused activation of the intrinsic laryngeal muscles, produced a modest increase in F0, a marked increase in Psub, no change in the open quotient (OQ), and an increase in the closing quotient (CQ). Phase quotient (Qp), which describes the interval between opening of the lower and upper fold margins, decreased with increasing RLNS.

Transtracheal stimulation of the recurrent laryngeal nerve

Phonation was induced in 10 mongrel dogs under general anesthesia by way of transtracheal stimulation of the recurrent laryngeal nerves under conditions of constant air flow. Although stimulation voltages were approximately 10 times the voltage required for direct stimulation, no cardiac or respiratory abnormalities were observed. Photoglottographic and electroglottographic signals were the same for both direct and transtracheally induced phonation. This phonation induction method can be used in chronic animal preparations to study vocal fold vibration sequentially and may be clinically applied to the treatment of patients with laryngeal problems that have failed to respond, or are not amenable, to standard forms of vocal rehabilitation.

Early vocal cord carcinoma in obese patients: a surgical lesion.

Early epidermoid carcinoma of the vocal cord is treated successfully by radiation therapy with high 5‐year survival rates, low morbidity, and preservation of excellent voice quality in most cases. Typically, surgery is reserved for salvage of radiation failure and provides overall 5‐year survival rates of 98% and 90% for T1 and T2 lesions, respectively. The extremely obese patient, often with a short neck and excessive amounts of subcutaneous fat, is difficult for both radiotherapist and surgeon to diagnose and treat. The recent observation of an unusually high rate of radiotherapy failure in a cluster of obese patients with early vocal cord cancer called attention to this problem. Because the larynx is near the thoracic inlet in obese patients, they are not suitable for administration of radiotherapy by accurate opposed lateral portals. The patients reported herein were treated entirely with anterior oblique portals. Of the five obese patients who underwent primary radiation therapy for early vocal cord cancer, three developed recurrent disease (60%) and a fourth developed a severe perichondritis requiring tracheostomy. Two patients with recurrent disease were successfully salvaged with total laryngectomy, while the third patient refused surgery and died 2 years later. The sixth patient was treated by partial laryngectomy with imbrication reconstruction and is alive and without evidence of disease 2 years following surgery.