We studied the three dimensional arrangement of collagen fibrils and elastic fibrils in human vocal fold by scanning electron microscopy after digesting cellular elements and collagen fibrils by formic acid treatment and after digesting cellular elements and elastic fibrils by 10% sodium hydroxide treatment. These studies revealed that the superficial layer consists of lumps of collagen fibrils and fine elastic fibrils running straight or coiling, the intermediate layer consists of thick bundles of collagen and elastic fibrils running longitudinally and fine coiling elastic fibrils and the deep layer consists of coiling elastic fibrils, and dense collagen bundles. It was speculated that collagen fibrils have a role to keep up the layer organization of vocal cords even in vibrating and elastic fibrils work to restore the transformed vocal cords to the original form quickly.
We also studied the distribution of oxytalan fibrils in vocal cords by aldehyde-fucusin staining.
Oxytalan fibrils distributed in whole area of connective tissue of vocal cords and large amount of the fibrils existed just under the epithelial basement membrane and around the muscle fibers.
It was speculated that oxytalan fibrils, connect all structures in vocal cords tightly.
If these fibrils; collagen fibrils, elastic fibrils and oxytalan fibrils were damaged and lose their functions, vibratory mode of vocal cords will be disordered.

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This article reviewed the recent findings on nitric oxide (NO) related to laryngeal innervation.1) NADPH-diaphorase (NADPH-d) histochemistry is considered to be as reliable as immunohistochemistry using anti-nitric oxide synthase serum for demonstration of NO in the central and peripheral innervation system. 2) NADPH-d positive nerve fibers were mainly distributed around the laryngeal gland and vessels. These nerve fibers were considered to be cholinergic and originate from NADPH-d positive neurons in the intralaryngeal ganglia. There is a species difference in the participation of NO in the laryngeal sympathetic innervation. 3) A few NADPH-d positive nerve fibers are distributed in the laryngeal epithelium, possible sensory fibers. were a few. The possibility of participation of NO in the proprioception of intrinsic muscles was pointed out. 4) NO is not involved in normal motor innervation.

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The polypoid vocal fold is a relatively common lesion in the field of laryngology. It affects mostly forties, fifties and sixties with a habit of heavy smoking. The membranous part of the vocal fold is intensively edematous and under the epitherium, abnormal substance, fluid and/or mucoid is contained. At first, we stripped the edematous part of the vocal fold entirely and payed a painstaking effort only to normalize the vocal fold shape. Such a technique is called “decortication”. Among the cases treated with such a technique, we had some cases with postoperative voice which was much worse than preoperative one. The stroboscopic examination revealed that there was no wave motion on the surface of the vocal fold. We thought that this result should be caused by scar formation after “decortication”. Therefore, we have newly designed a surgical technique for the polypoid vocal fold. Instead of stripping the whole membrane for normalization of the vocal fold shape, we only suck the abnormal substance under the membrane while maintaining the membrane itself. In addition, several sophisticated techniques like squeezing and pinching have been developed, resulting in excellent postoperative voice. For the polypoid vocal fold with uneven surface, we applied snare method to remove excessive amount of membrane, and to preserve the membrane especially at the free edge.
After resection of a part of membrane, we suck with a suction tube or pinch with forceps localized abnormal substance while observing severely the membrane at the lower surface of the vocal fold in order to avoid undesirable injury to the free edge membrane.
In this paper, a history of development of surgical techniques for the polypoid vocal fold was described. And we introduce a snare method especially for uneven polypoid vocal fold.

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Four cases of laryngeal papillomatosis were reported to illustrate the clinical features associated with this condition. A 42 year old male operated on by laryngofissure method had received the same surgery about 20 years before. Laryngeal stent was used for the fixation of a free skin flap which was implanted in a raw surgical surface for 3 months for preventing web formation. However, this resulted in a poor voice due to severe adhesion occurring between both cords. The second case, a 38 year old female, had laryngeal surgery 4 times because of recurrent laryngeal papillomatosis and had been treated with a 4,500 rad irradiation. We performed a single vocal cordectomy. No recurrence was observed but an inadequate voice ensued. A 9 year old boy suffering from dyspnea was referred to our clinic for a close examination of his upper respiratory tract. A large papillomatous mass was excised with carbon dioxide laser. Subsequent laser vaporization was performed for more precise removal of the residual disease. A 52 year old male was also operated on using YAG laser for laryngeal papilloma. The latter two patients showed good phonation after surgery. We surmise that laser surgery is recommended for preserving the structure and function of the vocal cords. As an assessment for wide spread laryngeal papillomatosis, laser surgery or a combination of laser treatment and removal utilizing forceps were acceptable according to several references for preventing frequent recurrences, thick web formation and poor voice after operation.

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Post-operative hoarseness of vocal nodules is due, for the most part, to inadequate procedure in the operation of the lesion. This inadequate procedure may be classified into two categories : incomplete and excessive resection.
Poor surgical technique, insufficient knowledge of vocal nodules and vibration of the vocal folds, excessive confidence in surgical technique are mentioned as causes of excessive resection. Incomplete resection can be treated by re-operation, however there is no effective step against excessive resection.
Comprehension of the vocal fold vibration, mastery of surgical technique, and avoidance of excessive resection are important as countermeasures.

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With the introduction of the laryngomicrosurgical techniques including sucking, squeezing, and pinching methods, marked improvement of postoperative results has been obtained in treating polypoid degeneration of vocal folds. In some cases, however, unexpected hoarseness continued after the operation. Since 1989 there have been nine such cases treated at our clinic. The causes of postoperative hoarseness were (1) over-resection of vocal mucosa in three cases, (2) recurrence of vocal edema in five cases and (3) phonation using false vocal folds in one case. Reoperation was necessary in a case of over-resection of vocal mucosa with a web at the anterior commissure and in two cases of recurrence of vocal edema, all of whom had been treated at other clinics. Steroid injection to the edematous vocal fold in two cases and polypotomy in a case using fiberoptic laryngeal surgical technique were performed yielding good results.
Over-removal of the mucosa, especially at the free mucosal edge and the anterior commissure, should be prevented as countermeasures for post-operative hoarse voice in laryngomicrosurgical treatment of polypoid vocal folds. Postoperative long-term follow up and early detection of recurrence also seemed important. To settle the recurrent polypoid vocal fold at an early stage, fiberoptic steroid injection manifested its effectiveness.

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Twenty-three patients, complaining of hoarseness due to unilateral recurrent laryngeal nerve (RLN) palsy, underwent vocal fold augmentation by an intracordal injection of atelocollagen. Sixteen of them were followed over seven months (7 months-7 years and 7 months, average 3 years and 5 months). Ten of these 16 maintained improved phonatory functions during a follow-up period and were classified as Group 1. Four of this group showed highly disturbed pre-injection phonatory functions more than the rest of Group 1 and were not satisfied with their post-injection voices. Two of these four underwent type I thyroplasty and another re-injection. The other six of Group 1 included three patients after arytenoid adduction. Group 2, including another four, did not show any improvement in their post-injection phonatory functions. Two of them underwent type I thyroplasty and re-injection, respectively. The other two (Group 3) showed a progressive improvement in their post-injection phonatory functions.
A major disadvantage of intracordal injection of collagen injection is a remarkable decrease in volume of the paralyzed vocal fold during a follow-up period. Repeated injection or type I thyroplasty is the choice for such a post-injection dysphonia. Collagen injection is not indicated. when the both vocal processes do not meet during phonation. Such a case requires arytenoid adduction combined with collagen injection or type I thyroplasty.

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Phonatory functions were compared among 25 patients with T1 glottic cancer (T1a : 18, T1b : 7) following the combined therapy of laser and radiation, 9 patients with T1-2 following radiation treatment alone, and 40 normal subjects (over 50 years old). Maximum phonation time (sec), air flow rate (ml/sec), vocal velocity index, pitch (Hz), pitch perturbation quotient (%), amplitude perturbation quotient (%), and normalized noise energy (dB) were obtained from the use of a phonatory equipment PS-77 and an acoustic analyser SH-10.
Moreover, phonatory dysfunctions in 6 of 7 patients with T1b glottic cancer were estimated on the basis of extent and depth of laser irradiation, and of post-operative laryngeal findings by fiberscope.
The results were as follows.
1. The mean values of phonatory parameters in normal subjects were MPT : 17.8 sec, AFR : 187 ml/sec, VVI : 45.5, pitch : 147 Hz, PPQ : 1.01%, APQ : 3.34%, and NNE : -11.1 dB respectively.
In comparison with the normal subjects, those values of radiation treatment alone coinsided closely, and those of T1 group indicated distinctly a decline of the aerodynamic functions and a change for the worse of the acoustic characteristics of voices. However, the difference of those parameters were statistically no significant between Tla and Tlb group.
2. After CO₂ laser surgery for T1b, laryngoscopy revealed web formation of the anterior commissure (28%), asynmetry and fibrosis of all affected vocal cords. Degree of the post-operative changes had been affected by the extent more than the depth of laser irradiation in glottis.
3. In T1b group, the mean values of phonatory parameters in the 3 patients with a marked postoperative change were a short MPT (6.2 sec), higher AFR (372 ml/sec) and VVI (104.3), and pitch : 225 Hz, PPQ : 1.79%, APQ : 4.00%, NNE : -5.6 dB, while, those in the 3 with a mild change were MPT : 18.0 sec, AFR : 155 ml/sec, VVI : 34.1, pitch : 146 Hz, PPQ : 0.25%, APQ : 2.56%, NNE : -14.2 dB, respectively.
Because of having the lesion in both vocal cords, CO₂ laser management for T1b glottic cancer has including more complex problems than that for T1a in the insure of favorable post-operative voices. At least, laser irradiation covered wide range of the bilateral vocal cords may be phonetically disadvantage. In the use of CO₂ laser, it is a necessary to control adequately the extent of laser irradiation in a combination with radiation therapy of curative dose.

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The purpose of the present study is to elucidate the functional roles of the laryngeal afferent inputs in controlling vocalization. Vocalization was induced by the electrical stimulation of the pontine call site (PCS) in ketamine anesthetised cats. Firstly, we investigated the effects of the laryngeal deafferentation on respiratory duration and voice quality during induced vocalization. Secondly, to investigate more detail of the laryngeal influences, the upper airway was isolated from the lower one. The airflow application to the isolated upper airway during PCS stimulation induced vocalization. We investigated the effects of the airflow or pressure to the upper airway on intralaryngeal muscle activity during PCS stimulation.
The laryngeal deafferentation decreased respiratory duration during PCS stimulation and affected voice quality with reducing the vocal fold adductor and tensor activities. The airflow to the isolated upper airway during PCS stimulation increased adductor and tensor activities and their durations. There was a critical subglottic pressure level at which adductor and tensor activities were suddenly increased with vocalization. Pressure application to the isolated upper airway with closed mouth and nostrils did not significantly affect the adductor and tensor activities.
These results suggest that the afferent input from laryngeal pressure receptors is not the main factor modulating the vocal movement, and that the laryngeal afferent inputs, such as stretch- and vibration-sensitive ones, play an important role in vocal motor control.

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The purpose of this study was to analyze the postnatal development of the intrinsic laryngeal muscles and the nucleus ambiguus motoneurons. The following measurements were taken : the number of intrinsic laryngeal muscle fibers; diameter of intrinsic laryngeal muscle fibers; the number of nucleus ambiguus motoneurons; and diameter of the nucleus ambiguus motoneurons. Measurements were taken at postnatal days (PND) 1, 3, 7, 14 and in mature Sprague-Dawley rats.
The results are as follows : 1) The number of intrinsic laryngeal muscle fibers is about 6800 at birth and does not increase thereafter. 2) The diameter of intrinsic laryngeal muscle fibers increases gradually; diameter at PND 14 is 1.5 times larger than that at PND 1, while diameter at mature age is 2.5 times larger. 3) The number of nucleus ambiguus motoneurons is 850 at birth and decreases to 740 at PND 7.4) The diameter of the nucleus ambiguus motoneurons increases gradually after birth, but remains unchanged after PND 14.
These results suggest that postnatal cell death in the nucleus ambiguus occurs within PND 7 and innervation of the intrinsic laryngeal muscles is completed by that time.

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Pemphigus vulgaris is a disease rarely encountered in otolaryngological practice. This report involves a case of asymptomatic pemphigus vulgaris of the larynx.
The patient was a 58-year-old woman who had an eight year history of dermatological corticosteroid therapy for her skin lesions. A laryngeal examination had not been performed because there had been no symptoms involving her throat. A superficial bleeding ulcer of the epiglottis was found incidentally during an upper-gastrointestinal endoscopic examination for her anemia. The patient was referred to us for further laryngeal examinations. She had no active skin lesions at the time of the first visit. Biopsy specimens taken from the epiglottis revealed acantholysis, which appeared on the intraepidermal vesicles. Histological diagnosis showed a laryngeal condition resulting from pemphigus vulgaris. Results of the pemphigus anti-body were negative but the results of the squamous cell carcinoma-related antigen (SCC-RAG) were increased. The ulcer improved with a double dose of the steroid. The epiglottis remained red and swollen.
A review of available literture reveals that laryngeal involvement is not such a rare manifestation of pemphigus vulgaris as might be supposed. We stress that the laryngeal examination is necessary in cases with pemphigus vulgaris, and the SCC-RAG is one of the tools for following up the clinical course.

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A 43 year old man was complaining of left central visual field deficit, hoarseness in breathing, dysphagia, and right shoulder pain after an acute infection of the upper airway. Physical examination revealed right associated laryngeal paralysis and left optic neuritis. Laboratory examination showed high parainfuruenza type 3 virus-antibody titers, suggesting meningitis caused by the said virus. For treatment, predonisolon was administrated starting with 80 mg. resulting in improvement of clinical symptoms.

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Schwannoma occuring from Schwann cells is a well capsulized benign tumor, and is not common in the larynx. Two cases of laryngeal schwannoma were described in this article. The first case was located in the left aryepiglottic fold and was excised via endolaryngeal microsurgery. The other was located throughout the cricothyroid ligament, and extended to the outside of the larynx and to the paraglottic space, and was removed by an external surgical approach. In both cases, diagnosis confirmed pathologically, but the origin of nerves was undetectable.

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