The Lombard reflex, a representative auditory feedback mechanism for laryngeal control, occurs when a speaker increases his voice level in response to an increase in the ambient noise level. This reflex has been employed as a clinical tool for determining simulated hearing loss, though the neural mechanisms underlying this reflex remain unclear. In decerebrate cats, repetitive electrical stimulation of the midbrain periaqueductal gray (PAG) induces natural-sounding vocalization. Recently, it has been suggested that auditory stimulation augments : 1) the intensity of voice induced by stimulation of PAG, and 2) the activities of the laryngeal adductor and expiratory abdominal muscles. These results indicate that auditory stimulation has excitatory effects on the activity of the laryngeal adductor and expiratory muscle motoneurons. The Lombard reflex consists of the auditory-laryngeal reflex and the auditory-spinal reflex accordingly. In this study, we aimed to clarify the circuit involved in auditory-laryngeal and auditory-spinal reflexes that may contribute to evocation of the Lombard reflex. Using an electrophysiological technique, an auditory relay projecting its axons to the intrinsic laryngeal motoneurons in the nucleus ambiguus was determined. Consequently, a dorsal nucleus of the lateral lemniscus (LLD) was identified. Moreover, an iontophoretical injection of sodium glutamate to the LLD augmented the activities of intrinsic laryngeal motoneurons. These results indicate that the neurons in the LLD may contribute to the evoking the Lombard reflex

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The distribution of capillaries in relation to muscle fiber types in the intrinsic laryngeal muscles (TA and PCA muscles in this paper) was investigated in comparison with common skeletal muscle (EDL muscle) in rats. The alkaline phosphatase stain method was applied to visualize the capillary, and the myosin ATPase stain method was applied to distinguish muscle fiber types. The mean cross section area of muscle fiber in EDL was greater than that of the intrinsic laryngeal muscles, though the ratio of capillaries per muscle fibers (C/F) in the PCA was significantly greater than that of the EDL. The capillary density (CD), number of capillaries per one sq mm, in the TA and PCA muscles was significantly greater than that of the EDL. These results suggest that the intrinsic laryngeal muscles are capillary rich in order to supply sufficient oxygen.

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Endolaryngeal microsurgery was performed on 1,858 patients at our clinic during the past 17 years. The totoal number of operations, including multiple procedures on individual patients, was 2,115. General anesthesia was used in all cases.
Vocal fold polyps, nodules, and polypoid growths accounted for 1,544 cases out of the total 2,115, or approximately 72.9%. The remaining cases included vocal fold leukoplakia, laryngeal cancer, cystoma and papilloma. These rates of occurrence are in line with those reported in previous studies.
This report will devote particular attention to those cases which required additional operations. Such operations were necessary in 108 patients, approximately 5.8% of the total; the number of extra operations performed was 149, approximately 7.0% of the total. The discrepancy between the percentage rate for patients and that for operations results from the performance of two or more additional operations in certain cases. The disorders most often requiring multiple operations were vocal fold leukoplakia, with 39 procedures performed, laryngeal cacer, with 38 procedures performed and polypoid vocal fold, with 32 procedures performed.

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MALT lymphoma is malignant lymphoma arising from mucosa-associated lymphoid tissue (MALT). A case of laryngeal MALT lymphoma was reported with a review of the literature.
A 60-year-old man was adimitted with a six month history. Laryngoscopy revealed smooth but thickened bilateral false vocal folds. Twice biopsies were performed from the submucosal whitegraysh mass. Histopathological examination and flow cytometric analysis of surface tumor markers revealed that the tumor was MALT lymphoma. The patient had systemic chemotherapy treatment. The therapy achieved complete remission and the appearance of his larynx returned to normal. He remains free of disease to the present time.

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There are many treatments of benign laryngeal papilloma. It is exceedingly difficult to control because of rapid recurrence after removal. In this report, two cases of with laryngeal papilloma effectively treated with interferon were presented. Case 1 was not controlled with the repeated laser surgery, but was cured by local injections of three million units of α-interferon followed by resection. Case 2 underwent local injection of β-interferon and resection. The laryngeal papilloma completely disappeared. The results indicated that local laryngeal injection of interferon was useful in the treatment of laryngeal papilloma.

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A case with juvenile laryngeal papilloma manifesting malignant change in excrescence was reported. This patient had suffered from dyspnea since 1955, when he was one years old. A huge tumor occupied the larynx and trachea, and the pathological diagnosis was papilloma. He underwent laryngomicrosurgery using CO2 laser many times at a neighboring hospital. Although the pathological diagnosis of papilloma was determined upon the first visit to our hospital, the tumor enlarged quickly after a month. Since his final histological diagnosis was squamous cell carcinoma, he underwent total laryngectomy and partial pharyngo-esophagectomy for radical treatment, followed by radiotherapy (60Gy). Some discussions were made concerning the malignant transformation, etiology and treatment of papilloma.

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