We have investigated the respiratory function of human glottis, over the past 10 years. This paper present results of three consecutive studies for evaluation of the respiratory glottic movements. We have carried out two human and one animal study, including (1) A video fluoroscopic measurement of the glottic airway width in healthy subjects and patients with pulmonary emphysema during eupnea, (2) Effects of a positive pressure lung inflation on respiratory glottic movements in anesthetized dogs, and (3) A glottic area determination by newly developed Acoustic Reflection System in normal subjects and patients with pulmonary emphysema. The results were as follows : “The expiratory glottic narrowing” were a significant phenomenon in subjects with some type of disease condition such as pulmonary emphysema (in study 1). We observed that a positive air way pressure narrows the glottis more markedly than a decrease of the lung volume. The airway pressure was one of the most important contributing factor in expiratory glottic movement (in study 2).Also, We were able to measure dynamic changes of glottic airway area by the acoustic reflection technique introduced by Jackson and Fredberg in 1977 (in study 3). Respiratory glottic movements may reflect airway-lung condition especially changes of the intra-airway pressure caused by changes of the airway resistance in various airway diseases.
Measurements of respiratory changes in the glottic area may be useful for estimation of airway characteristics and pathophysiology in patient with pulmonary diseases. Further investigations are needed for more information.
The acoustic reflection technique is a unique, non-invasive technique for evaluating cross-sectional area of airway, especially for estimation of changes in glottic airway area due to respiratory glottic movement.

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The main clinical objectives of phoniatric function tests are in the establishment of degree severity of the vocal disorder and the evaluation of the effect of therapy. The clinical significance of phoniatric function tests was evaluated in reference to recurrent nerve palsy (RNP) from diagnosis and through the course of treatment in this paper.
Psychoacoustic evaluation is an ideal phoniatric function test to determine the total quality of voice but the results are variable since it is dependent on the individual conducting the evaluation. The results of the maximum phonation time coincides with the clinical course of the treatment. Recently, with the use of the computer, numerous parameters for acoustic analyses of speech can now be performed in a very short time. Pre-operative and post-operative amplitude perturbation quotient, pitch perturbation quotient and noise level in patients with RNP, laryngeal polyp and Reinke's edema were determined. In cases in which severe deterioration of the quality of voice was observed, the course of treatment coincided with the changes in the quality of voice. For determination and analysis of pre-operative and post-operative conditions in RNP, the EGG is ideal.
The superiority of an apparatus which can display the vocal pitch, intensity, flow rate, etc. as a feedback for voice therapy in real time is also reported in this paper.

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Laryngostrobography is a newly developed method whose purposes are easy visualization and quantitative analysis of vibrations of the vocal fold (V.V.F) synchronously with some voice-related signals (V.R.S) including the voice signal, EGG, subglottic pressure on laryngostroboscopy. The system employs the strobo-motion-analyzer The image of the V.V.F through the CCD videocamera on laryngostroboscopy is held to the 128 field image memories at real time and the aforermentioned three V.R.S synchronized to the trigger pulse of the laryngostroboscope are processed through the A/D converter simultaneously. These V.R.S are superimposed to the image of the V.V.F through the superimposer and displayed on the video-monitor and the CRT-display. Furthermore, the whole vibratory periods of the arbitrarily sectioned image of the vocal fold and the V.R.S synchronized to the each vibratory phase of the V.V.F are ordered in time series and superimposed as the single still image strobogram.

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Six adult cats weighing 2.2kg-4.7kg were anesthetized with intramusclar injection of ketamine hydrochloride. The left recurrent laryngeal nerve (RLN) was transsected at the level of the second tracheal ring and both cut ends were ligated. Electrically induced vocalization was performed after Kanai's method. (Horsley-Clarke coordinates AP : 0, L4.5-5.5, H-3.0--6.0) (stimulation 0.2ms, 50-100 μA, lasting 5-10s) Then EMG of the throarytenoid muscle (TA) and the posterior cricoarytenoid muscle (PCA) were recorded. Besides, single afferent discharges from laryngeal sensory receptors of paralyzed vocal cord were recorded during evoked vocalizations.
In this study, 25 weeks after transection of RLN the EMG of left TA showed recruitment, but the electromyographical activity of the left PCA was not observed. 20 weeks after neurorraphy of the left RLN and the left Ansa cervicalis, the activity of the left TA was almost the same as that of the control side. The EMG of left PCA showed the continuous activity during vocalization. However, in all cases, no return of vocal cord mobility was observed. The rate of single afferent discharge from laryngeal sensory receptors on paralyzed side was corresponded to fundamental frequency change during evoked vocalization. This result suggests that the central nervous system has received informations about paralyzed vocal cord vibrations from larynx during evoked vocalization.

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Reinnervation and subsequent paradoxical movements of the motor nerve after injury is well known in the facial nerve, ocular nerve, peroneal nerve, etc. as well as the recurrent laryngeal nerve (RLN). Way of the experimental injury to the RLN at a level below 15 mm from the lower margin of the cricoid cartilage was accomplished two different methods : one to be neurorrhaphy under microscope after transection of the nerve and the other to be freezing by ophthalmological forceps at a temperature below 80 degrees for five minutes. This latter procedure allows the Schwann sheathe and perineurium to remain intact but damages the endoneurium. Movements of the pathological vocal fold were observed macroscopically and monitored regularly by electromyogram (EMG) from one week to nine months. Redistribution of the motoneuron originating from regrowth of the nerve fiber around the injured RLN was histologically verified by horseradish peroxidase (HRP) at the time of the EMG monitorings. The target muscles for observatory analyses were determined to be the posterior cricoarytenoid muscle (PCA) and thyroarytenoid muscle (TA). Monitoring of these muscles between the adductor and abductor is essential in order to assess the paradoxical movement after regrowth of nerve fibers. It was suggested that following transection of the nerve sprouting began three months later than it did in the group that underwent freezing injury two weeks after trial when the distribution rate was calculated in the nucleus ambiguus of the medulla oblongata. Furthermore, the numbers of sprouting fibers increased at one point beyond the normal level (in our study) of 90 six months after injury and gradually normalized in both groups at the 9 months. The rate of excessive growth in the first transected group was superior to the second freezing group. This result suggests that the rate of paradoxical movement following misdirected reinnervation is greater in the transected group than in the freezing group. This was verified by monitoring of the EMG. In both groups, HRP stained target neuron cells affecting the PCA muscle were observed in the localized control dorsoventral area at the more cephalad site. However, aberrant motoneurons also appeared out of the normal area and in the caudal and ventral regions (TA motoneuron). This also suggests paradoxical movement after reinnervation of nontarget organs.

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The three-dimensional CT image reconstruction technique has been applied to examine four cases with laryngeal disease. A carefully designed data input system made it possible to utilize the multiformat camera film as well as the on-line or off-line image data in digital format. Using the volume rendering technique, reconstructed images can be displayed in various colors with different transparency, which enables layered transparent soft tissue presentation on the laryngeal cartilages. The image can rotated and cut at the optimal direction.
In a case with recurrent nerve palsy, abduction of the arytenoid cartilage and the atrophied vocal cord was clearly visualized. In three cases with laryngeal trauma, fracture and dislocation of cartilages, scar formation and vocal fold deformity were visualized. This technique is useful to understand the laryngeal function disorder with the three-dimensional image with layered superimpose of the laryngeal cartilages, soft tissue and the vocal fold.

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Participation of various neurotransmitters in the canine inferior laryngeal nerve was studied by immunohistochemistry and NADPH-diaphorase (NADPH-d) histochemistry in combination with retrograde labelling using cholera toxin B subunit-gold (CTBG) as a tracer.
In the nucleus ambiguus, nearly all of cells labeled with CTBG had choline acetyltransferase (ChAT) -like immunoreactivity (ir) and many labeled cells had calcitonin gene-related peptide (CGRP) -like ir. In the dorsal nucleus of the vagus, many CTBG labeled cells had ChAT-like ir and some of CTBG labeled cells had CGRP-like ir. In the nodose ganglion, CTBG labeled cells were scattered in the ganglion. In these cells, CGRP-, substance P (SP) -and tyrosine hydroxylase (TH) -like immunoreactive cells were detected. NADPH-d positive cells were also observed. In the superior cervical ganglion, most CTBG labeled cells had TH-like ir and labeled cells with NPY-like ir were also found. Labeled cells with VIP-like ir were also detected, although the number was small.
These results indicate that many kinds of neurotransmitters participate in the sensory and autonomic innervation as well as motor innervation of the larynx through the inferior laryngeal nerve.

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Injectable bovine collagen has been used for vocal fold augmentation in human subjects. The purpose of this study was to examine the wound healing and tissue reaction of canine vocal folds in which collagen was injected. Two forms of bovine collagen, cross-linked and not cross-linked, were injected into vocal folds of dogs; the animals were killed 9 weeks and 17 weeks after injection.Immunohistochemical study in three growth factors, basic fibroblast growth factor (bFGF), transforming growth factor-β (TGF-β) and platelet-derived growth factor (PDGF), was performed. Not cross-linked collagen delayed normal wound healing process and implants tended to be absorbed in a long-term. On the other hand, cross-linked collagen did not disturb the wound healing process and tended to persist in the tissue with good stability.

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Serotonin (5-HT) and substance P (SP) fibers are known to be distributed in the nucleus ambiguus (NA). In this study, retrograde tracing and immunohistochemistry methods were used to compare the distribution of the 5-HT and SP with the location of the laryngeal motoneuron pools innervating the posterior cricoarytenoid (PCA), the thyroarytenoid (TA), and the lateral cricoarytenoid (LCA) muscles.
The PCA pool was located in the ventral part of the NA; the LCA and TA pool was located in the dorsal part of the NA. The density of 5-HT immunoreactive fibers and varicosities was higher in the ventral part of the NA, where the PCA motoneuron pool is located, than in the dorsal part of the NA. The density and pattern of distribution of SP immunoreactive fibers and varicosities were similar to those of the 5-HT immunoreactive fibers and varicosities. The present results, that the patterns of 5-HT and SP innervation vary according to the type of motoneurons and their projections to the larynx, suggest that these putative neurotransmitters may be more involved in influencing the activity of the abductor than that of the adductor of the vocal cords.

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In order to clarify the functional subunits in a single laryngeal muscle, electrophysiological and histochemical studies were performed. The thyroarytenoid muscle was divided into the rostral compartment and the caudal compartment. The posterior cricoarytenoid muscle was divided into the lateral and the medial compartment.
EMGs were recorded during normal respiration and mechanically-evoked cough from rostral (r-TA) and caudal (c-TA) compartment of thyroarytenoid muscle along with lateral (l-PCA) and medial (m-PCA) compartment of posterior cricoarytenoid muscle. Histochemical detection of myosin ATPase and EMGs revealed that the type 2B fiber was most abundant in r-TA and gradually decreased in the order of c-TA, l-PCA and m-PCA.
During cough, these four compartments of muscles equally exhibited bursting discharges. L-PCA activity during cough exhibited a ninefold increase over that during respiration, while m-PCA exhibited a threefold increase. These data suggest that the intrinsic laryngeal muscle consists of different compartment with distinctive motions. Hence the intrinsic laryngeal muscles should be considered as a complex of some functional subunits.

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The main point of the X-ray laryngostroboscopy (X-ray stroboscopy) which was first developed. by Saito is that the trigger pulse for the strobo light of the laryngostroboscope is used as the external trigger for the pulse X-ray radiation of the pulse X-ray angiography system.
The critical defect of the X-ray stroboscopy of human phonations from the frontal plane was that the vibratory image of the vocal cord was masked by the overlapped image of the cervical vertebrae.
This defect was, first in the world, completely resolved by recent development of the digital subtraction X-ray stroboscopy. This is a combined system of the laryngostroboscope and the digital subtraction angiography system. Clear vibratory images of only the vibrating portion of human vocal cords in the frontal plane can be extracted by the digital subtraction of the image of the cervical vertebrae.
The essential principle of the vibration of human vocal cords during phonation is the travelling wave phenomenon whose wave crest travells from the lower portion to the upper portion of the vocal cord continuously.

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The three dimentional (3D) laryngostroboscopy was newly developed in cooperation with Shinko Optical Co., Ltd. and Flovel Co., Ltd. The system is composed of a 3D laryngotelescope with two TV cameras, a control unit, a monitor display, a wireless liquid crystal shutter eyewear, and a laryngostroboscope.
The specifications of the 3D laryngotelescope which has the two lines of vision are as follows. The diameter of the telescope is 15mm. The angled view is 70°. The field of view is 35°. The distance between the centers of the two object lenses is 6mm. The angular parallax is 7°. The diameter of the field is 25mm at the standard focal distance of 50mm, and 15mm at the nearest focal distance of 35mm.
The time multiplexed stereopsis is adopted in this system. Each field from the right and left TV cameras is mixed alternately and written in the pair of the two field memories in sequence in the frequency of 60 Hz, while it is read out and displayed on the monitor display in a high frequency of 120 Hz in order to avoid flicker.
Stereoscopic views with sufficient depth perception of wave crests rising from the medial/lower surface and travelling toward the lateral/upper surface of the vocal cords were obtained through the three dimensional (3D) laryngostroboscopy.

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The present study was carried out to investigate the aerodynamic characteristics of tracheoesophageal (TE) phonation. Five excellent TE speakers served as the subjects. The subpseudoglottal pressure, mean flow rate and audio waveform were recorded simultaneously during steady phonation. The results were as follows; 1) The subpseudoglottal pressure and mean flow rate were positively related in two of the subjects, negatively related in one subject and not linearly related to each other in the final two subjects. 2) There was a pressure gradient recorded between the points above and below the narrowing which existed prior to the pseudoglottis in two of the subjects. 3) Fundamental frequency and subpseudoglottal pressure showed positive linear correlation in all of the subjects only when the pressure was measured just below the pseudoglottis. The variability of the relationship between subpseudoglottal pressure and air flow rate is supposed to be the result of the complex configuration and volume expansion of the subpseudoglottal cavity as well as the possibility of pseudoglottal manipulation by the subjects. The pressure measured just below the pseudoglottis seems to be acceptable value for the driving pressure of the pseudoglottal vibration.

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Aerodynamic parameters during optimal easy phonation were compared among 6 patients with vocal polyps, 32 patients with glottic cancer (T1 and T2) and 9 normal subjects.
Subglottal pressures (cmH₂O) directly extracted by the miniatured pressure tranceducer through the glottis, mean air flow (ml/sec), pitch (Hz) and intensity (dB) of voices, glottal resistance (cmH₂O/l/sec), subglottal power (×10₆ erg/sec), and laryngeal efficiency were obtained with the use of PS-77phonatory equipment and the computerized phonatory system PI-100.
The cases with vocal polyps presented with slightly high values of mean subglottal pressure (the mean value of 9.0cmH₂O) and glottal resistance (the mean value of 38.5cmH₂O/l/sec) and glottal power 3 times greater than that of the normal subjects. The mean value of laryngeal efficiency was about a half level of that in the normal subjects. In the cases of glottic cancer, the subglotal pressures were inceased to the mean value of 11.6 cmH₂O in Tla, 21.7cmH₂O in Tlb and 25.7cmH₂O in T2 cases respectively. The Glottal resistance and subgottal power were significantly increased by as the T stage became advanced. In contrast, the laryngeal efficiencies decreased as the T stage was advanced : the mean value of 1.27 in T1a, 0.50 in T1b, and 0.25 in T2 cases.

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In this study, 92 patients with supraglottic cancer during the last 10 years (28.5% of 323 laryngeal cancer cases) were investigated from clinical and pathological aspects, of the 92, 7 was in stage I, 29 in stage II and 56 was in stage III and IV.
Curative radiotherapy with the dosis over 60Gy was given in 41 cases (44.6%). Of the 41, 25 were in stage I or II and local recurrences were found in 5 cases (20.0%). They underwent total laryngectomy subsequently. The 10-year crude survival rate of curative radiotherapy was 83.3% in stage I, 89.5% in stage II and 18.8% in stage III and N. In 3 cases with T3N0M0 with vocal foldfixation, the tumor was completely cured with radiotherapy alone. Two of them had complete recovery of vocal fold movements, whereas. One kept having the vocal fold fixed without disease.
Among 37 supraglottic cancer cases who had bad cervical lymph node metastasis, any patient did not survive with the larynx conserved.
In supraglottic cancer cases, the depth of cancer invasion must be determined based on clinical examinations of the primary site before selection of the method of therapy.

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A case of primary laryngeal tuberculosis is reported. A 43-year-old female with intermittent hoarseness for 6 months was referred to our department due to progressive hoarseness and slight dyspnea. Fiberscopic examination revealed severe adhesion of a white coat to the bilateral false and true vocal cords. Although we suspected laryngeal tuberculosis, plain X-ray film of the chest revealed no abnormal findings. The histopathological result obtained by a biopsy under direct laryngoscopy was useful in obtaining the diagnosis. Although a polymerase chain reaction was used to detect myobacterial DNA sequences in her sputum, false negative data was obtained for tubercle bacillus, suggesting a limitaion of this method. The clinical course was fair with a good response to medical therapy.

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