This paper presents a critique of clinical methods currently used for assessment of laryngeal function. Acoustic, aerodynamic and perceptual analysis are discussed. It is suggested that acoustic analysis is limited relative to establishing a specific diagnosis but may have application in screening for laryngeal malignancy. The problems identified with aerodynamic assessment are those associated with the warm-wire anemometer. Criticisms of the perceptual scales widely adopted in Japan focus on the fact that parameters selected are arbitrary and other measures may be more precise in describing vocal hoarseness. Crossing all measures of vocal function is the need for standard calibration procedures. The authors conclude that considerable study is needed before laryngeal function tests can be considered a true clinical examination of the vocal system.

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Rapid technological advances have facilitated development of ultrasonoglottography (UGG) first developed at Chiba University in 1964. The newly developed ultrasound laryngography (ULG) unit is a high-resolution electronic linear scanner that provides both a B-mode image of the larynx and a M-mode display of vocal fold movement. The ultrasonic pulse repetition rate can be changed in three steps; 2.5, 5 and 10KHz. Two kinds of electronic linear scan probes are used for the ultrasonic pulse reflection method. One has a carrier frequency of 7.5MHz with 128 elements, and the other is a micro intraoperative probe with 54 elements. The waveform of vocal fold vibration (ultrasonoglottogram) is obtained by using a cursor on the B-mode display to identify the vocal fold and then switching to the M-mode function. To visualize vocal fold vibration the authors developed a X-Y monitor that permits simultaneous recording of the M-mode, variant M-mode, pulse transmission display, and the signal of photo-electric glottogram. Data is presented that documents how UGG is used to help describe the mechanism of voice production and diagnosis of various laryngeal diseases.

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The CO₂ laser has been widely used for the treatment of benign and malignant tumors in the head and neck area. The laser provides excellent hemorrhage control by sealing the capillaries. Hemorrhage control is further improved by the simultaneous use of the CO₂ laser and the Nd-YAG laser. The laser method of treatment also results in the minimal dissemination of cancer cells, improving the long-term outcome.
The advantages and disadvantages of laser surgeries are as follows :
1) Advantages
Good hemorrhage control, No dissemination of tumor cells, No tissue ischemia, Little or no pain. No side effect on or edema of tissue surrounding the tumor, Maintain satisfactory phonation, Repeated operations amenable
2) Disadvantages
Hard to determine border line of irradiation, Applicable mostly to Tl or early stages of cancer with No (if N1 should be dissectable) and MO, Limitation of exposure of tumor and surrounding tissue, Unequal laser power distribution to tumor
The current study reports the results on 52 consecutive patients. Survival rate as of December 1988 is 50/52 (96%), and all of the living patients are tumor-free histologically. Results support the contention that tumors of the larynx classified as Tla can be cured by laser alone, Tlb tumors can be cured by laser alone or laser plus external irradiation. For any single patient, laser surgery may be repeated up to three time, at which time total laryngectomy should be considered. Laser surgery controls operative hemorrhage better than other procedures, and results in minimal operative pain.

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A review of laryngeal endoscopy in diagnosis and treatment of head and neck problems is presented. The review includes the historical development of optical endoscopes used to observe the larynx with emphasis on the technological advances in the last fifteen years that have facilitated the routine introduction of endoscopy into laryngeal practice is discussed. The development and consolidation of high quality laryngeal telescopes and fiberscopes, strong cold light sources, and video documentation are also described. Based on literature review and personal experience, the authors conclude that : (1) the 60 degree forward oblique viewing telescope allows close-up observation of the larynx and endolaryngeal microsurgical manipulation perorally with excellent image, (2) the flexible fiberscope is easily employed in pediatric and adult cases pernasally and perorally; and (3) for examining dysphonias, laryngeal stroboscopy is an easy and practical examination procedure when coupled with appropriate endoscopes, a strong stroboscopic light source and high quality CCD color video camera and recording system.

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To date there has not been wide spread adoption of anastomosis and neuromuscular pedicle transplantation for the restoration of dynamic function to the paralyzed vocal fold. Recently, electrical stimulation of the paralyzed muscle (PACING) has been reported as a means of restoring dynamic function in cases of laryngeal paralysis. The present paper reports the use of this PACING procedure in five adult canines. Triggered by the signals from the cricothyroid muscle, electrical stimulation resulted in bilateral vocal fold synchrony for phonatory adduction. The data suggests that electrical stimulation is a promising treatment for unilateral recurrent laryngeal nerve palsy. Discussion of potential problems incurred with long-term implantation, and advantages of miniaturization of the electrical stimulation apparatus are also included in this paper.

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This paper describes an aerodynamic and electromyographic study of the sneeze. A sneeze is characterized by a deep inspiration followed by an abrupt expulsive expiration. The sneeze consists of three phases; inspiratory (preparatory), compressive (minimum flow) and expiratory. In the compressive phase the airway is temporarily obstructed while the intrathoracic pressure is elevated by contractions of the expiratory muscles. The study attempted to determine if the point of obstruction was at the level of the glottis similar to that observed in the cough. Aerodynamic studies using the body plethysmograph show that intrathoracic compression is greatest during the compressive phase, and that expiratory air, when present, is expelled only through the mouth. Electromyographic data show that the diaphragm (DIA) and posterior circoarytenoid (PCA) muscles are activated during the inspiratory phase and then the rectus abdominis (RA), thyroarytenoid (TA) and levator veli palatini (LP) muscles are activated during the compressive and expiratory phases. The interrelationship among these muscle groups appears to be extremely delicate as seen in the transition between the compressive and expiratory phase where an abrupt change in TA and PCA activity is observed while the RA and LP continue to be active. In cases where delayed activation of the PCA is observed the subglottic pressure created was not sufficiently high to perform an effective sneeze. From these aerodynamic and electromyographic data the authors conclude that in the sneeze the glottis is the occlusive point necessary for the elevation of the intrathoracic pressure.

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A histological study of the vocal fold mucosa of 64 larynges obtained from autopsies of subjects ranging from 70-104 years of age is reported. When the results are compared to the authors' studies of younger age groups significant differences are observed. Comparisons of larynges of the same age also reveal sex differences. In males, the membranous vocal fold tended to shorten, the cover tended to thin, the intermediate layer of the lamina propria tended to thin in association with atrophy of elastic fibers, and the deep layer of the lamina propria tended to thicken in association with an increase in collagenous fibers. In females, these tendencies were less marked, and the superficial layer of the lamina propria tended to become edematous and thickened.

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There is general consensus that the larynx is the organ of voice. Less well recognized is the role it serves in speech production. Recently, it has been shown that the larynx is a major contributor to articulatory adjustments. These laryngeal adjustments are produced by coordinated activities of the intrinsic and extrinsic muscles of the larynx. Since the introduction of a fiberscopic and electromyographic techniques to the field of experimental phonetics, the nature of laryngeal adjustments in different languages has been explored in more detail than heretofore was possible. Further, the use of different types of glottography and computer-controlled image analysis opened a new scope in laryngeal physiology. In the present paper, using a combination of recently developed experimental techniques, the physiological correlates of each the four basic features of laryngeal articulatory adjustments are discussed. The basic features of the laryngeal articulatory adjustments addressed consist of :
1) abduction-adduction of the vocal folds with special reference to voicing distinctions;
2) constriction of the false vocal fold and other supraglottal structures related to whispering and laryngealization gestures;
3) changes in the length and thickness of the vocal folds with respect to prosodic control; and
4) vertical movements of the larynx.

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Following treatment of precancerous lesions such as dysplasia recurrence and/or carcinoma may develop. The current study presents data to elucidate factors occurring in malignant change through an investigation of the interrelationship between dysplasia and squamous cell carcinoma. The ras p21, c-myc and EGF-R proteins which are produced by each oncogene implicated in dysplasia (ras, myc and erb-B) were immunohistochemically identified from human specimens (38 with dysplasia, 51 with carcinoma, and 20 normal laryngeal epithelium) with the Abidin-Biotin-Peroxidase complex staining method. Results obtained are summarized below :
1. A high positive rate of straining in dysplasia, particularly in histologically high grade specimens, occurred at nearly the same positive rate as in well and moderately differentiated squamous cell carcinoma. The data indicate that positive staining of ras p21, in particular, can serve as a signal of the occurrence of malignant change.
2. The c-myc protein was not found in dysplasia. Even in carcinoma specimens, it was only found in the cancer cell nuclei. This was interpreted to mean that the myc oncogene was related to cell malignancy.
3. The EGF-R in dysplasia was found in the atypical cell. These results suggest that EGF-R expression may be one factor indicating malignant change.
The authors conclude that while the significance of malignant change in dysplasia was not directly assessed in this study, that the study presents sufficient data to warrant further research in this area.

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The etiology of juvenile laryngeal papilloma (JLP) has been suggested to be a viral condition related to the presence of genital warts in the mother at the time of delivery. No direct demonstration of human papilloma virus related to the larynx and genital organ has been established. The incidence of JLP in all areas of Thailand suggests some local endemicity and presents an opportunity to elucidate the etiological bases of this disease. In the current study clinical and virological studies of juvenile laryngeal papilloma were studied in Thai children suffering from the recurrent respiratory papilloma and airway obstruction. Sixty two cases are included in the clinical study and 30biopsy specimens are included in the histopathological and virological examinations. The histological examinations reveal the papillomas were characterized by papillary growth of well differentiated squamous cells with an orderly maturation pattern. No virus particles were demonstrated in the papillomatous tissue sections studied by electron microscopic examination. The DNA dot blot analysis revealed the presence of HPV 11 related sequences in the papillomatous tissue of 6 cases. Clinically, onset was observed before 4 years of age in 80% of the children, and was most frequently observed in first born children. The prevalence of JLP differs in different parts of Thailand. The study does not provide strong support for a viral condition related to the presence of maternal genital warts as the etiological bases for JLP.

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From May to July in 1985, and again in June of 1988 a mass screening for early detection of laryngeal cancer was conducted in Fukui prefecture. All persons who responded to a newspaper add for free voice assessment were examined. A total of 918 people, 542 males and 376 females from 30 to over 90 years of age were studied. The age distribution included 95 people in their thirties, 288 in forties, 288 in their fifties, 152 in their sixties, 84 in their seventies, 8 in their eighties and 1 who was 90 years of age. The screening included a routine indirect mirror laryngoscopic examination. Ten glottic laryngeal cancers were detected, nine of them were Tla cases and one was a T3. Thus, approximately 1.1% of the population studied were identified as having laryngeal cancer. This cancer rate is considerably higher than that reported for cancer screening for other organs. Of the 918 persons screened there were no false positives. These results demonstrate the usefulness of this screening technique for early detection of glottic laryngeal cancer.

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Idiopathic laryngeal deviation (ILD) is defined as an unusual deviation of the laryngeal framework in otherwise healthy patients when no possible cause in the history is detected. Typical factors associated with ILD include cervical trauma, thoracic surgery and laryngeal or hypopharyngeal carcinoma. In this paper, characteristic findings of ILD are discussed and several problematic cases presented. Most ILD are found in aged, male patients demonstrating a displacement of the thyroid notch toward the right and consequent asymmetry between the right and left thyroid alae. Similar distortion is found in the cricoid cartilage, and the left cricothyroid joint which induces a swelling in the neck that may push the left thyroid lobe inferiorly. Typical characteristics revealed by laryngoscopic examinations include 1) the anterior commissure is displaced to the right, 2) the left vocal cord is nearly obscured by the edematous false vocal cord and its mobility seems to be somewhat limited and 3) a pooling of secretions is observed in the left pyriform sinus. The authors suggest these characteristics should lead the examiner to question a diagnosis of laryngeal or hypopharyngeal carcinoma made from a CT scan. However, when laryngeal or hypopharyngeal carcinomas on the left side are associated with ILD, it is difficult to make a precise estimation of the extent of invasion of the carcinoma. It is important to recognize that the ILD characteristics may be unrelated to the carcinoma to avoid oversurgery.

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Over the past three decades a variety of surgical techniques have been developed for voice restoration following laryngectomy. The underlying principle of these procedures is to divert pulmonary air into the gullet where vibrations of the tissue creates the sound used for speech production. To achieve successful surgical voice restoration voice production must be compatible with normal deglutition. Many of the surgical techniques resulting in good voice production report frequent problems with aspiration indicating they have not been equally successful in achieving normal deglutition. The current paper presents a simple primary surgical technique that provides a new sound source and normal deglutition. This primary surgical technique uses a membraneous tracheal flap for voice restoration combined with bilateral esophageal muscle flaps to avoid problems with aspiration.

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Although there have been numerous articles of chapters on treatment of laryngeal trauma, there is still much to be learned. The choices of treatment are based on consideration of sustaining lift of voice as well as the type of wound and immediacy of the trauma.
Six cases of laryngeal trauma are reported in this paper. Four cases were self inflicted acute penetrating wounds requiring immediate surgical repair to stop severe hemorrhaging. Another case was a thyroid cartilage fracture and displacement caused by low velocity blunt injury, and was repaired by an open surgery. The last patient suffered from a hoarse voice after high velocity injury resulted from a huge fishhook in the larynx. At the time of surgery the wound was healed and a small area of granulation tissue was found in the subglottic anterior commissure. Laser surgery was successfully performed and the voice returned to normal.

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A retrospective study of 30 pediatric patients treated for dyspnea from airway stenosis is reported. All patients were treated at Mie University hospital between 1980 and 1989 reported. Seventy percent of the patients were less than one year of age. The most frequent causes of dyspnea were acute subglottic laryngitis (8 cases) and laryngomalacia (4 cases). Seven cases had difficulty in decannulation. Difficulty in decannulation resulted from prolonged intubation in two cases and laryngeal disease in five cases (laryngeal lymphangioma, laryngomalacia, subglottic hemangioma, acute subglottic laryngitis and laryngeal web). In the present retrospective series of infants, severe stenosis required external laryngeal surgery and for lesser degrees of stenosis a T-tube stent was adequate.

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