The electroglottogram (EGG) has been used to obtain details of vocal fold vibration. Applications of the EGG, however, are limited in use for voice disorders since characteristics of EGG waveforms associated with vocal fold vibrations are still poorly understood. We analysed the EGG waveform characteristics to compare them with simultaneous measurements of supra and subglottic pressure in the normal male subject sustaining the vowel /a/ at constant pitch with different intensity levels. The results are : The periodicities of the consequent frequency are completely coincident among the EGG wave, supra and subglottic pressure waveforms at different intensity levels. With regard to the amplitude variations of the EGG waveform in the vocal cycle, the increasing amplitude corresponded with a rapid increase of subglottic pressure and a decrease of supraglottic pressure which is indicative of the closing phase of the vocal folds. The gradual fall of amplitude associated with the parting of the vocal folds corresponded with an increase of supraglottic pressure from negative values and maintenance of negative subglottic pressure. The negative flatter portion of EGG wave corresponding to the opened phase exhibited higher positive supra glottal pressure and lower pressure of the subglottic even at different sound pressure levels. When increasing the intensity during constant pitch phonation, the values of the contact quotient and contact speed index decreased, and the contact closing slope became steeper.These findings reveal the tendency of increasing vocal tension following louder vocalization. Simultaneous measurement of EGG waveforms, and supraglottic and subglottic pressures might provide useful and detailed information for understanding EGG waveforms, laryngeal dysfunction and/or research for voice disorders.

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Cough in Laryngeal Allergy : A Review Cough is common in patients with laryngeal allergy. It is well known that irritant receptors and C-fiber endings participate in the cough reflex caused by mechanical and chemical stimulation of the laryngeal mucosa. Intraepithelial nerve fibers corresponding to the irritant receptors or C-fiber endings are observed in the laryngeal mucosa. These fibers are very dense in the arytenoid region, which is considered to be a primary site for the allergic reaction. Supposedly, susceptibility to the cough reflex is enhanced in patients with laryngeal allergy.The inflammatory mediators may stimulate or sensitize the sensory receptors related to cough reflex. Laryngeal C-fiber endings are stimulated by histamine, and applying histamine to the laryngeal mucosa elicits continual cough. Prostaglandin is likely to stimulate the irritant receptors and to trigger the cough reflex. There is controversy concerning the participation of leukotriene in cough reflex. Thromboxane is likely to participate in the cough reflex. Bradykinin stimulates airway C-fiber endings, which in turn invokes the cough reflex. Further investigations are needed to clarify the neural mechanism causing coughing in laryngeal allergy.

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[in Japanese]

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It is believed that smoking causes benign or malignant neoplasms in the larynx. One of the possible mechanisms proposed is the inactivation of folic acid and vitamin B₁₂ that occurs in smokers, thus leading to malignant changes in the respiratory epithelia. The serum concentrations of folic acid and vitamin B₁₂ of various patients in our outpatient clinic have been measured, and it was shown that these are relatively low in smokers and ex-smokers within 2 years from cessation. One of the vocal cord leukoplakia patients presented has shown dramatic improvement by the treatment of halting smoking and oral supplement of folic acid and vitamin B₁₂.

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Adductor spasmodic dysphonia is a vocal disorder of uncertain etiology. Section of recurrent laryngeal nerve or injection of botulinum toxin has been used as an effective treatment. But they are not satisfactory long-term treatments. Bilateral thyroaritenoid muscle myectomy is performed by microlaryngoscopic method to four patients of adductor spasmodic dysphonia. Good speech results are obtained immediately after the operation, and no side effect is observed. No patient has experienced a return of symptoms, after one-year follow-up. Bilateral thyroaritenoid myectomy may be a hopeful new long-term approach to spasmodic dysphonia treatment.

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Cases with malignant tumors of the larynx other than squamous cell carcinomas were reported. 595 patients (551 males, 44 females) with previously untreated malignant tumors of the larynx who had undergone treatment in the Kurume University Hospital from 1980 to 1996 were retrospectively reviewed. There were 13 cases (2.2%) with malignant tumors of the larynx other than squamous cell carcinomas : 3 patients with carcinoid tumor, 2 with carcinosarcoma, 2 with verrucous carcinoma, 2 with ATL, 1 with undifferentiated carcinoma, 1 with chondrosarcoma, 1 with pseudo sarcomatous squamous cell carcinoma and 1 with rhabdomyosarcoma. Histologically diagnosis before the operation was determined in only one case (carcinoid), while the other 12 cases were diagnosed after the operation. Since in many cases preoperative diagnosis based on biopsy was not reliable for these rare malignant tumors of the larynx, final true diagnosis was determined based on resected laryngeal specimens. On the other hand since the grade of malignancy depends strongly on the histological property, an appropriate choice of treatment is definitely important.

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A case of laryngopharyngeal fistula in 53 year-old man was reported. In this case, we suspected that his laryngopharyngeal fistula had been caused by poor blood circulation in the larynx, because he had been intubated and he had been a diabetic. To prevent recanalization the larynx and pharynx were reconstructed. In the reconstruction of a larynx with laryngopharyngeal fistula, we needed to take care not to obstruct the function of the larynx, deglutition, phonation and the air way.

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[in Japanese]

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