Sensory stimuli to the larynx evoke a laryngeal adductor reflex mediated by the brain stem via superior and recurrent laryngeal nerve. There are some reports that abnormal laryngeal reflex results in disorders of phonation and respiration. The clinical use of Larynx-evoked Brain Stem Response (LBR) as a research tool to study polysynaptic reflex pathway is considered to have a great advantage. The purpose of this report is to review the literature concerning LBR and to speculate the clinical application of LBR. In present time, there are detailed reports of LBR about validity of response, latencies, generator sources, on cat. However, there are a few reports of adaptation for use in humans.

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The authors investigated vibratory mode of the vocal fold seen from the tracheal side utilizing a high speed cinematography. Twelve excised canine larynges were used in the experiment. Several marks were made with Indian ink on the lower surface of the vocal folds. After taking cinematography, the larynges were fixed, sectioned in a frontal plane and stained for histologic examination. Movements of the free edge, lower lip, mucosal upheaval and marks were analyzed. The mucosal upheaval appeared on the lower surface of the vocal fold during vibration. Mucosal waves started from the mucosal upheaval, which itself vibrated with a small amplitude. The mucosal upheaval was placed more laterally when the air flow rate was increased. But the mucosal upheaval occured at the same location on the mucosa as that before the increase of air flow rate. This was because the increased subglottic pressure displaced the vocal fold laterally and upward. When vocal fold tension was increased, the mucosal upheaval was situated more medially. The location of the mucosal upheaval on the mucosa moved medially compared to its original position before the tension increase. Histologic examination indicated that the mucosal upheaval arose on the lower surface of the vocal fold between the free edge and the area where the muscular layer was close to the epithelial layer.

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The change in fundamental frequency (Fo) with the change in transglottal pressure (Ps) in phonation was studied at two different Fo levels within modal registers and at one Fo level in falsetto using ten human subjects. The method employed was a sudden increment of intraoral pressure during sustained phonation. The magnitudes of Fo change with respect to Ps change in falsetto were larger than those in high-pitched modal register in nine out of the ten subjects. The magnitudes of Fo change with respect to Ps change in high-pitched modal register were smaller than those in low-pitched modal register in six out of the ten subjects. Three subjects, however, showed the contrary results. One subject showed no difference. These rather unstable results obtained in high-pitched modal register against low-pitched modal register imply that the Fo change due to the transglottal pressure change during speech is not significant in linguistic realization.

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The purpose of this study was to obtain normative data for acoustic analysis of voice. Four acoustic parameters, pitch perturbation quotient (PPQ), amplitude perturbation quotient (APQ), normalized noise energy for 0 to 4 kHz (NNEa) and normalized noise energy for 1 to 4 kHz (NNEb) were measured in sixty normal subjects (thirty males and thirty females). The subjects uttered /e/ vowel three times at the comfortable pitch and loudness level. Each sample was acoustically analyzed with the use of Rion SH-10. Intra-subject variation was small in the majority of the subjects but a few subjects presented large variations. The distribution of the measured values of NNEb differed significantly between the males and females whereas that of the other three parameters did not differ significantly between the two sexes. The normal limit (p < 0.05) was 0.43% for PPQ, 1.71% for APQ and20.4 dB for NNEa in both sexes. The normal limit for NNEb differed between men and women ;-9.8 dB for men and-4.4 dB for women. Values greater than these limits should be regarded to be abnormal.

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The glottal efficiency defined by van den Berg was measured with two different techniques. 1. The glottal airway resistance and efficiency during vowel production were estimated using the Painters modified noninvasive method of the device of Smitheran and Hixon (1981). Five normal males were the subjects. Measurements were conducted when the subjects uttered sylabble /pa : / three times successivly. 2. By means of Nagashima PS-77-201, glottal efficiency was determined in 38 normal adults, 23 males and 15 females. Problems inherent to the two methods were discussed.

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A mouthpiece is frequently used when the maximum phonation time (MPT), fundamental frequency (F₀) and sound pressure level (SPL) are measured simultaneously with measurements of airflow. The purpose of this study was to determine the influences of the mouthpiece on MPT, F₀ and SPL. Forty normal adults (20 males and 20 females) were the subjects. The mouthpiece did not significantly influence MPT. The mouthpiece tended to lower F₀ but the influence of the mouthpiece on F₀ was small and clinically not important. SPL was significantly affected by the mouthpiece : the SPL value for the softest phonation was greater by 2 dB, that for the loudest phonation was smaller by 8-9 dB, and the SPL range was smaller by 10 dB when the subjects Phonated into the mouthpiece than when phonated without the mouthpiece.

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This paper presents a rare case of poorly differentiated adenocarcinoma of the larynx. The patient was 59-year-old man who had been surgically treated for mucinous adenocarcinoma of the stomach in 1971. In 1988, he developed transitional cell carcinoma of the urinary bladder and adenocarcinoma of the larynx and both lesions were surgically treated. Vertical partial laryngectomy was conducted for the laryngeal lesion. The patient has been disease free for 25 months. The combination of the three primaries seen in this case is a very rare condition. A brief review of literature was given.

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The adductory movement of the vocal fold is produced mainly by the lateral cricoarytenoid muscle and the abductory movement is produced by the posterior cricoarytenoid muscle. In recurrent laryngeal nerve paralysis, the position of the paralized vocal fold can be largely influenced by the balance of the tonus of these antagonistic muscles. Marked medialization of the paralyzed vocal fold was obtained by transection of the posterior cricoarytenoid muscle in a patient with left recurrent laryngeal nerve paralysis, resulting in a remarkable improvement of hoarse voice. Experimental studies proved that transection of the posterior cricoarytenoid muscle caused medial displacement of the vocal fold.

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There are many kinds of therapeutic methods for laryngeal papilloma. However, it is even now exceedingly difficult to eradicate lesions completely. Recurrences after surgery occur frequently. One of the causes of recurrences is considered to be an incomplete removal. We believe an incomplete removal of papilloma is caused by lack of precise visualization of the lesion during surgery. Bleeding, coagulated blood and/or carbonized tissue produced by laser obscures the image of remaining papilloma. We have developed a new surgical method, called “tow-stage operation”. Two successive surgeries are conducted with an interval of 10 days. At the second operation, bleeding, coagulated blood and carbonized tissue of the first operation disappear and the laryngeal image is much clearer. When some lesions are still found, they are removed at the second operation. This paper presents a case of 26-year-old male with laryngeal papilloma who had been operated one month before at another hospital. A laryngeal endoscopic examination revealed multiple papillomas especially at the glottis. The first surgery was performed with carbon dioxide laser on 16th Apr. 1990. Visible lesions appeared to be removed completely. The second operation was carried out 10 days after the first operation and small remaining lesions was removed with CO₂ laser. The patient has been disease free for eight months.

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