Tatsutoshi Suzuki

NEUROMUSCULAR JUNCTION CHANGES IN AGED RAT THYROARYTENOID MUSCLE

Dynamic remodeling of neuromuscular junction (NMJ) structure is postulated as a cause of age-related muscular atrophy. Direct study of NMJ morphology in laryngeal muscles is important to our understanding of age-related decrements in voice and swallowing. The morphology of NMJs was studied in a rat model to compare young and old specimens of thyroarytenoid muscle — a muscle critical to airway protection and phonation. Fluorescent, triple-label immunohistochemical analysis and confocal microscopic visualization were used to analyze the structure of NMJs. We found that laryngeal NMJs underwent significant changes that were similar to those observed after denervation. Specifically, the axon terminal area was significantly reduced, there were a number of postsynaptic acetylcholine receptor areas unoccupied by nerve terminals, and there was increased variability in end plate architecture in the old muscles. The results of this study increase our understanding of the age-related morphological changes in the larynx, and may serve as a baseline to test the effectiveness of future interventions.

Age-related alterations in myosin heavy chain isoforms in rat intrinsic laryngeal muscles.

Deficits in voice and swallowing are found in the elderly, but the underlying neuromuscular mechanisms are unclear. A potential mechanism may be denervation-induced muscle fiber transformation to a slower-contracting type of muscle fiber. This study examined young, old, and denervated rat laryngeal muscles (lateral thyroarytenoid, lateral cricoarytenoid, and posterior cricoarytenoid) to examine differences in myosin heavy chain (MHC) composition. Results of sodium dodecyl sulfate–polyacrylamide gel electrophoresis analyses indicated that all muscles were composed predominately of type IIB MHC. With aging and denervation, type IIB was reduced and type IIX, a slower-contracting isoform, was increased in the lateral thyroarytenoid and lateral cricoarytenoid muscles. In the posterior cricoarytenoid muscle, the MHC composition was relatively unchanged. These findings suggest that aging may affect laryngeal adductory function by altering muscle fiber type composition to a slower-contracting isoform, in a manner similar to that observed with denervation.

Laryngeal-Respiratory Kinematics are Impaired in Aged Rats

Fatigue and weakness in the elderly are the functional consequences of underlying neuromuscular decline. However, little is known about the manifestations of aging in the larynx. This study evaluated the manner in which laryngeal senescence affects laryngeal-respiratory kinematics by videorecording laryngeal motion in both young and old rats. Recorded images were digitized, and glottal displacement and movement rate were measured. The results indicated that the amplitude of change in glottal angle was significantly diminished, and laryngeal movement durations were prolonged in the old animals. These findings may be due to functional constraints on the respiratory system, impaired laryngeal-respiratory interactions, or decrements in vocal fold tension with age. Because of the serious and pervasive nature of dysphagia and communicative impairments in the elderly, research that specifically examines the manifestations and causes of these impairments is of great importance.

Multiple primary malignancies in the head and neck: a clinical review of 121 patients.

A total of 121 multiple primary malignancies (quadruple, n ¾ 2; triple, n ¾ 11; and double, n ¾ 108) were treated at the Department of Otorhinolaryngology, Kitasato University Hospital between July 1972 and December 1998. Of the 108 patients with double primary malignancies, 18 had synchronous double primary malignancies (SDPM), which were defined as occurrence of the index tumor and second malignancy within 6 months of each other, and 90 had metachronous double primary malignancies (MDPM), which were defined as occurrence of the index tumor and the second malignancy separated by a period of >7 months. MDPM was subdivided into MDPM-F (head and neck malignancy occurred as the first tumor; n ¾ 55) and MDPM-S (head and neck malignancy occurred as the second tumor; n ¾ 35). Of the 55 patients with MDPM-F, 27 (49.1%) of the second malignancies were found in the digestive tract, 12 in the stomach (21.8%), 8 in the esophagus (14.5%) and 7 in lower digestive tract tumors (12.7%). The 3- and 5-year survival rates of MDPM-F were 79.2% and 62.3%, respectively. Differential diagnosis between multiple primary malignancy (MPM) and multicentric tumors is often difficult when the lesions involve the oral cavity, pharynx and esophagus. We suggest that it is beneficial to follow patients for as long as possible in order to facilitate diagnosis of tumor recurrence, metastasis and MPM.

Glottal configuration, acoustic, and aerodynamic changes induced by variation in suture direction in arytenoid adduction procedures.

Arytenoid adduction is a phonosurgical procedure in which the arytenoid cartilages are approximated to reduce posterior glottal gap size and improve voice. Voice outcomes following arytenoid adduction are not always optimal. The goal of this study was to systematically vary suture direction and force of pull on the arytenoid cartilages in a human excised laryngeal model to determine the optimal combination of factors for reducing glottal gap and improving voice. Several factors demonstrated significant effects. Changes in suture direction and force of pull affected glottal configuration in both the horizontal and vertical planes. Increased force of pull on the muscular process resulted in increased adduction of the vocal process for all suture directions. Changes in suture direction and force of pull also affected acoustic and aerodynamic measures of induced voice. Therefore, voice outcomes can be optimized with arytenoid adduction if the vocal fold plane is accurately adjusted.

A comparative study of suturing techniques in microlaryngosurgery.

Different types of suturing device for microlaryngosurgery were compared. A new device was developed based on the results of this comparison, and proved to be very useful.

Distribution of two types of mast cells in the nasal mucosa after chemosurgical treatment of allergic rhinitis using trichloroacetic acid.

To evaluate the efficacy of chemosurgery using trichloroacetic acid (TCA)for allergic rhinitis, two types of tissue mast cells [tryptase-positive, chymase-negative mast cells (MCT) and tryptase-positive, chymase-positive mast cells (MCTC)] in the nasal turbinate mucosa were immunohistochemically identified and their distribution was assessed in clinical cases of patients who underwent unilateral TCA treatment. A comparison of the number of MCT and MCTC between the treated and nontreated sides indicates that both types of mast cells are significantly decreased in number in the treated side both in epithelial and lamina propria layers. The results indicate that TCA treatment was effective in suppressing MCT infiltration, regarded as a major cause of antigen-dependent allergy.

Three-dimensional Computer-reconstructed Image for Studying Cancer Extension Within the Hypopharynx

Hypopharyngeal cancer is one of the head and neck cancers with poor prognosis. This is due to the unpredictable extension of the local disease and the high ratio of distant metastasis. To verify the morphological behavior of hypopharyngeal cancer, whole-mount horizontal serial sections were developed using the larynges obtained from total pharyngolaryngoesophagotomy. The technique of processing high-resolution three-dimensional (3D) images of the larynges using Nikon Cosmozone 2SA software is presented. Two representative surgical specimens were used and 3D images reconstructed. In these two particular cases, the cancer infiltrated superiorly through submucosal lymphatic ducts and formed separate daughter nests under the intact mucosal epithelium far above the main tumor. 3D images enhanced the morphological features of these cases. These cases also suggested the difficulty of defining the upper resecting limit in the operation of hypopharyngeal cancer. 3D reconstruction is and will be a crucial modality for studying the morphological behavior of hypopharyngeal cancer.

An immunohistological study of the localization characteristics of thymus and activation-regulated chemokine in the allergic inferior turbinate mucosa with reference to the effectiveness of trichloroacetic acid treatment

To investigate the background of the effectiveness of trichloroacetic acid (TCA) treatment, we examined the localization of thymus and activation-regulated chemokine (TARC) on allergic inferior turbinate mucosa using immunohistological methods. After obtaining informed consent, only one side of the inferior turbinate was treated with 80% (wt/vol) TCA solution under topical anesthesia using 4% lidocaine with epinephrine in 19 cases of allergic rhinitis. Among those, 17 cases did not show clinical improvement and underwent nasal septal reconstruction surgery and turbinectomy. Bilateral inferior turbinate specimens were obtained. The untreated turbinate specimens showed positive TARC findings. The positive findings were confirmed in the outer side of cytoplasm in the stratified ciliated columnar epithelium but not in the goblet cell. In the lamina propria, the glandular tissue and a few of the infiltrated lymphocytes just beneath the epithelium up to the depth of 120 m were found TARC-positive (TARC+). The average number of positive cells in one microscopic visual field using 1003 magnification was 3.97 6 4.04. On the other hand, the epithelium of the TCA-treated side showed positive findings only in two cases. The TCA-treated side also showed a relative decrease in infiltrated cells. Even in areas where there still were infiltrated cells, they were confirmed to be TARC-negative (TARC2) after TCA treatment. It is considered that the regenerated epithelium after TCA treatment originates from the glandular epithelium with negative TARC expression existing in the area deeper than a 120-μm level and that this immunohistological change would lead to the effectiveness of TCA treatment.

Middle ear metastasis of thymoma

OBJECTIVE We report an extremely rare case of thymoma which developed middle ear metastasis along with acute sensorineural hearing loss in the contra ear. METHOD We present a case report and a review of the world literature concerning thymoma metastases to the middle ear. RESULTS A 54-year-old female patient with thymoma who developed middle ear metastasis along with acute sensorineural hearing loss in the contra ear. CONCLUSION We have not found out thymoma metastases to the middle ear in the past.