Koichi Omori

Mechanical properties of the vocal fold : stress-strain studies

The viscoelasticity of the vocal and ventricular folds was experimentally assessed by analyzing the stress-strain relationships obtained using a newly developed measuring system. The degree of stiffness of the mid-membranous portion of the vocal fold was less than that near the anterior commissure or the vocal process. The ventricular fold was much less stiff and significantly more viscous than the vocal fold. At the membranous portion of the vocal fold, the degree of stiffness was less and that of viscosity greater at 2 mm above and below the free margin than at the free margin itself.

Acoustic characteristics of rough voice: Subharmonics*

This study investigates the relationship between rough voice and the presence of subharmonics, which correspond to smaller yet distinct peaks located between two consecutive harmonic peaks in the power spectrum. Spectrum analysis was undertaken in 389 pathologic voices, of which 20 had subharmonics. Although all 20 voices had roughness perceptually, 8 had normal jitter and/or shimmer. The degree of roughness had a significant inverse relationship with the frequency of subharmonics. By digital signal processing, sound samples with various types of subharmonics were synthesized and perceptually analyzed. Power and frequency of subharmonics in the synthesized sound also had significant relationships with the degree of roughness. Rough voice is acoustically characterized not only by jitter and shimmer but also by the presence of subharmonics in the power spectrum. Subharmonics are important acoustic properties for objective evaluation of rough voices.

Steroid injection for Reinke's edema using fiberoptic laryngeal surgery.

Objective Since 1990, we have performed steroid injections into the vocal fold under topical anesthesia using fiberoptic laryngeal surgery (FLS) in an outpatient clinic. The aim of this study was to retrospectively assess the usefulness of this treatment method in 44 patients with mild Reinkes edema. Material and Methods Using fiberoptic monitoring of the larynx, a curved injection needle was inserted via the oral cavity and triamcinolone acetonide was injected into Reinkes space of the bilateral vocal fold. Results Remission or improvement was observed in almost all patients in terms of both patients self-rating of hoarseness and endoscopic vocal fold findings The maximum phonation time was a mean of 9.0 s before operation and 11.4 safter operation, and this increase was significant (p < 0.01). Voice pitch also improved, from 168 to 181 Hz, in female patients, and this increase was also significant (p < 0.05). Conclusion Steroid injection is considered to be useful for treating mild Reinkes edema.

Regeneration of mastoid air cells in clinical applications by in situ tissue engineering

Objectives: To regenerate of the mastoid air cells and their functions for the treatment of incurable otitis media.

Dopamine-secreting carotid body tumor

Paragangliomas often occur in the head and neck region and the carotid body is the most common site. However, a catecholaminesecreting carotid body tumor is rare, and dopamine-secreting tumors are especially unusual. In treatment of the tumor, the intraoperative control of hypertension is important. In this article, we report one case of a dopaminesecreting carotid body tumor that was operated on successfully under good control of blood pressure.

Transplantation of neural stem cells into explants of rat inner ear.

Damage and loss of hair cells in the inner ear is the most frequent cause of hearing loss and balance disorders. Mammalian hair cells do not regenerate in the conventional ways. To regenerate the hair cell in the mammalian inner ear we transplanted neural stem cells into explants of rat inner ear. The stem cells integrated successfully into the sensory epithelium of the vestibular organs, but not into the organ of Corti. This method is useful to investigate efficient ways to transplant stem cells into the inner ear.

Thyroid gland flap for glottic reconstruction after vertical laryngectomy

A thyroid gland flap was devised and applied in five cases of vertical partial laryngectomy to correct the laryngeal defect. The upper pole of the thyroid gland, dissected along with the superior thyroid artery and vein, was placed in the wound after removal of the tumor to compensate for the loss of bulk, and relined using a cervical skin flap. Good phonatory function was obtained without any disturbance of respiration or deglutition. The thyroid gland flap was adjustable to the size of the defect and easily placed in the larynx. Follow-up study for 6 to 18 months after the surgery revealed that the flap was less likely to shrink than the other flaps because of its abundant blood supply.

Tissue engineering for the regeneration of the mastoid air cells : a preliminary in vitro study

Mastoid is a pneumatic bone, composed of small interconnecting chambers covered by a mono-layer of mucosa with an abundant blood supply. One of its main functions is gas exchange according to the concentration/pressure gradient. The final goal of our research project is to regenerate mastoid air cells and their unique physiologic functions. The aim of the present study is to determine appropriate cultivating conditions for the cells cultured on the surface of artificial hydroxyapatite. In our in vitro experiment, to imitate the skeleton of mastoid bone, we used two types of three-dimensional hydroxyapatite (3D-HA), i.e. with a high (90%) and low (60%) percentage of micropores. The former type was divided into two groups: collagen-coated and non-coated. Canine mucosal- and bone marrow-derived stromal cells (BSCs), from the oral floor and femur respectively, were harvested and cultured on the 3D-HA under different conditions. To estimate the proliferation/distribution of the cultured cells over the surface of the 3D-HA, these cells were stained with the dye DiI and hematoxylin-eosin. There were no significant differences in the proliferation of cultured cells on the 3D-HA with high and low percentages of micropores. Collagen-coated HA was a better material for the cultured cells compared with the non-coated HA. Co-cultured mucosal and BSCs proliferated better than those cultured separately. In conclusion, this tissue engineering technique may be applied for the regeneration of mastoid air cells.

Acute coalescent mastoiditis and acoustic sequelae in an infant with severe congenital neutropenia

We report a 2-month-old boy with severe congenital neutropenia (SCN), who developed acute necrotizing otitis media and coalescent mastoiditis due to methicillin-sensitive Staphylococcus aureus. The infection fulminantly progressed within a day to a subtotal perforation of the tympanic membrane, destructive bony changes of ossicles, lateral subperiosteal abscess, and suppurative labyrinthitis. Despite the combined treatment with intravenous antibiotics and granulocyte colony-stimulating factor, the infection resulted in mixed hearing impairment. Much attention should be given to prompt diagnosis of otomastoiditis in SCN, a rare congenital disorder, since resultant acoustic sequelae may affect subsequent speech development and intellectual ability.

Reconstruction of the anterior commissure with a free mucosal flap

INTRODUCTIONnTo prevent stenosis and adhesion of the anterior commissure in the laryngeal reconstruction, we devised a technique of relining using a free labial mucosal graft and human fibrin glue.nnnMATERIALS AND METHODSnA single large piece of mucosal flap was prepared, folded at the anterior commissure, and sutured onto the raw wound of the larynx from both sides of the posterior glottis. Alternate suturing from both right and left sides was performed anteriorly, and the wound on the laryngeal lumen was fully covered by the mucosal graft. We applied this technique on a patient with laryngeal stenosis and two patients with laryngeal cancer.nnnRESULTSnWithout the use of a stent, we successfully reconstructed the anterior commissure and obtained a good result in voice quality in each case.nnnCONCLUSIONnLarge mucosal defects including the anterior commissure should be relined to acquire good voice quality. Relining using a free mucosal flap was a useful method since there were no limitations to size and placement. The adhesive property of human fibrin glue was indispensable in this procedure.