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Papers - Ogawa, Kaoru

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突発性難聴発症直後における耳鳴の経時的変化

Inoue Yasuhiro, Kanzaki Jin, Ouchi Toshiaki, Ogawa Kaoru, Saito Hideyuki, Harada Tatsuhiko

Audiology Japan 39 ( 1 ) 84-89 1996.02

Research paper (scientific journal), Joint Work

Electrocochleography during experimental cochlear ischemia of the guinea pig

Ogawa Kaoru, Kanzaki Jin, Ogawa Shigeo, Tsuchihashi Nobuaki, Inoue Yasuhiro, Sato Minako, Ikeda Shunya

Acta Oto-Laryngologica 116 ( 2 ) 253 - 256 1996

ISSN 0001-6489

It has been postulated that impairment of cochlear blood flow (CoBF) is one of the most important causes of hearing loss occurring during acoustic neuroma (AN) surgery. However, it remains unclear how the degree of cochlear ischemia influences the evoked responses in electrocochleography (ECochG) which has been used for monitoring cochlear functions. In the present study, we investigated alterations in ECochG during cochlear ischemia of varying degree in the guinea pig. In order to induce cochlear ischemia, the anterior inferior cerebellar artery (AICA) was mechanically compressed via the transclival approach. The compression of AICA resulted in a reduction of CoBF in 55 out of 70 guinea pigs. A constant reduction of CoBF was maintained during the compression of AICA in 44 (63%) guinea pigs. CoBF abruptly decreased upon compressing AICA, and promptly recovered after releasing the compression. N1 and N2 in ECochG were also altered by compression. During 3-min ischemia, N1 and N2 disappeared in 36% and 41% of the cases, respectively. The residual CoBF in cases whose N1 and N2 disappeared was significantly lower that that in other cases whose N1 and N2 were sustained during 3-min ischemia. In addition, there was a tendency that the lower the residual CoBF was, the shorter the survival time of N1 and N2. In cases whose NI and N2 did not disappear, the prolongation of N1 and N2 latencies after 3-min ischemia was positively correlated to the residual CoBF. On the basis of these results, we discuss the mechanisms underlying the changes in CoBF and ECochG during cochlear ischemia, and conclude that the degree of cochlear ischemia during AN surgery can be estimated with ECochG.

Basic and clinical aspects of hearing preservation in acoustic neuroma surgery

Kanzaki Jin, Ogawa Kaoru, Matsunaga Tatsuo

Practica Otologica 89 ( 3 ) 285 - 295 1996

ISSN 0032-6313

Hearing preservation is one of the ultimate goals of acoustic neuroma (AN) surgery. In this paper, we present the surgical results of hearing preservation surgery in our department, as well as our recent basic research on hearing preservation in AN surgery. Subjects consisted of 95 AN patients who underwent hearing preservation surgery via the extended middle cranial fossa approach and the middle cranial fossa approach. The overall hearing preservation rate was 51%. From the analysis of surgical results, we discussed the indications for hearing preservation surgery and the evaluation of pre- and post-operative hearing. In addition, we proposed a new classification system for pre- and post-operative hearing evaluation. We also present our basic research on "the relationship between cochlear blood flow and electrocochleographic findings during cochlear ischemia", and "the morphological studied of the VIII cranial nerve in AN patients". The changes in N1 and N2 in electrocochleography depended on the cochlear blood flow. Thus, we can estimate the degree of cochlear ischemia using the electrocochleography. Furthermore, the impairment of cochlear blood flow and cochlear nerve damage could be distinguished by the electrocochleographic findings. The morphological findings of the VIII cranial nerves of AN patients demonstrated tumor invasion in approximately 67% of the cochlear nerves, suggesting that total tumor removal together with hearing preservation could not be performed in these patients. In addition, gliosis in the transitional region of the cochlear nerve in AN patients was observed, which might lead to a change in capillary distribution. Angiogenesis was also found in tumor tissues from the cochlear nerve. These morphological findings indicated that the impairment of cochlear blood flow may be easily induced by manipulation during tumor removal, especially those around the transitional region.

Classification of hearing results after resection of acoustic neuromas. Extended Middle cranial fossa approach

Kanzaki Jin, Shiobara Ryuzo, Ogawa Kaoru, Inoue Yasuhiro, Satoh Yasuo, Yoshihara Shigemitsu, Toya Shigeo

Proceedings of the 2nd International Conference on Acoustic Neurma Surgery and 2nd European Skull Base Society Congress 227-230 1996

Research paper (scientific journal), Joint Work

Facial nerve preservation in acoustic neuroma surgery with stimulus microinstruments. Extended middle cranial fossa approach

Kanzaki Jin, Shiobara Ryuzo, Ogawa Kaoru, Inoue Yasuhiro, Satoh Yasuo, Yoshihara Shigemitsu, Toya Shigeo

Proceedings of the 2nd International Conference on Acoustic Neuroma and 2nd European Skull Base Society Congress 131-136 1996

Research paper (scientific journal), Joint Work

Electrocochleography during experimental cochlear ischemia of the guinea pigs

Ogawa Kaoru, Kanzaki Jin, Ogawa Shigeo, Tsuchihashi Nobuaki, Inoue Yasuhiro, Satoh Minako, Ikeda Shunya

Acta Otolaryngology 116 253-256 1996

Research paper (scientific journal), Joint Work

免疫異常モデルマウス（MRL/lpr）における難聴と組織学的研究--柴苓湯の影響について--

Inoue Yasuhiro, Kanzaki Jin, Ogawa Kaoru, Saito Hideyuki, Harada Tatsuhiko

耳鼻臨補89 16-16 1996

Research paper (scientific journal), Joint Work

Electrocochleography and cochlear blood flow during experimental cochlear ischemia of the guinea pig

Ogawa K, Kanzaki J, Ogawa S, Tsuchihashi N, Inoue Y, Sato M, Ikeda S

Acta Otolaryngol (Stockh) 116 253-256 1996

Research paper (scientific journal), Joint Work

聴神経腫瘍における聴力保存の基礎と臨床

Kanzaki Jin, Ogawa Kaoru, Matsunaga Tatsuo

耳鼻臨床 89 ( 3 ) 285-295 1996

Research paper (scientific journal), Joint Work

メニエール病におけるグリセロール負荷後の耳鳴とEOAEの変化について

Inoue Yasuhiro, Kanzaki Jin, Ouchi Toshiaki, Ogawa Kaoru, Ogata Akira, Yoshihara Shigemitu, Sato Yasuo

Otol Jpn 5 ( 5 ) 603-607 1995.12

Research paper (scientific journal), Joint Work

Purinergic receptor is coupled to inositol trisphosphate second messenger system in the cochlear lateral wall

Ogawa K, Kanzaki J, Schacht J

Proc Sendai Symposium 5 ( 1 ) 129-132 1995.12

Research paper (scientific journal), Joint Work

P2y purinergic receptors coupled to phosphoinositide hydrolysis in tissues of the cochlear lateral wall

Ogawa K, Schacht J

NeuroReport 6 ( 11 ) 1538-1540 1995.07

Research paper (scientific journal), Joint Work

蝸牛遠心性神経系の情報伝達とイノシトールリン酸・・生化学的アプローチから・・

Ogawa Kaoru

Otol Jpn 5 ( 2 ) 97-104 1995.05

Research paper (scientific journal), Single Work

P2y purinergic receptors coupled to phosphoinositide hydrolysis in tissues of the cochlear lateral wall

Ogawa K., Schacht J.

NeuroReport 6 ( 11 ) 1538 - 1540 1995

ISSN 0959-4965

The tissues of the lateral wall of the cochlea, spiral ligament and stria vascularis, maintain homeostasis of the inner ear through the production of endolymph and regulation of cochlear blood flow. We examined the effects of purinergic agonists on the release of inositol phosphates (InsPs) in intact isolated lateral wall tissues of the Fischer-344 rat. After preincubation with myo-[³H]-inositol, stimulation with the P2 purinergic agonist ATP-γ-S resulted in a concentration-dependent increase in the formation of [³H]InsPs. The P2 purinergic agonist α,β-methylene ATP (AMP-CPP) was a weaker stimulant, and the P1 purinergic agonist adenosine was ineffective. These results are consistent;with the presence of P2y receptors and a purinergically controlled InsPs second messenger system in the cochlear lateral wall.

Hearing preservation by the extended and nonextended middle cranial fossa approach for acoustic neuroma

Kanzaki J., O-Uchi T., Ogawa K., Shiobara R., Toya S.

Skull Base Surgery 4 ( 2 ) 76 - 81 1994

ISSN 1052-1453

The results of 248 cases of acoustic neuroma surgery carried out mainly by the extended middle cranial fossa approach during a 16-year period from 1976 to 1991 are analyzed. Hearing preservation was attempted in 69 cases and successfully achieved in 35 (51%) cases. Hearing was preserved in 24 (57%) of 42 cases in which a tumor was 20 mm or smaller in diameter, pure-tone hearing level was 50 dB or lower, and speech discrimination score was 50% or higher. The hearing preservation rate (76%) in the cases with a tumor extending 3 mm or less from the internal auditory canal was much higher than in cases with a larger tumor. Hearing was preserved in three of seven cases with a tumor of 21 mm or larger and in two of four cases of neurofibromatosis type 2. The evaluation of postoperative hearing is also discussed.

Evaluation of hearing recovery in patients with sudden deafness

Yamamoto Minako, Kanzaki Jin, Ogawa Kaoru, Ogawa Shigeo, Tsuchihashi Nobuaki

Acta Oto-Laryngologica 114 ( S514 ) 37 - 40 1994

ISSN 0001-6489

It is still difficult to evaluate the efficacy of treatment of sudden deafness. Effective methods of therapy have been reported in some studies and other studies have reported spontaneous recovery. In The present study, we assessed the correlation between hearing recovery and various parameters measured during recovery. We used three parameters: hearing gain, relative hearing gain, and recovery rate. We found that the recovery rate during recovery and the parameters measured on the 7th treatment day demonstrated the greatest correlation. The recovery rate on the 7th day of treatment was found to be useful for predicting the final hearing recovery. Comparison of the recovery rate on the 7th day of treatment may be useful for the evaluation of the efficacy of treatment of sudden deafness.

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Aplastic anemia and sudden sensorineural hearing loss

Ogawa Kaoru, Kanzaki Jin

Acta Oto-Laryngologica 114 ( S514 ) 85 - 88 1994

ISSN 0001-6489

In the present study, the clinical and audiological features of 3 patients with aplastic anemia who subsequently developed sudden sensorineural hearing loss are reported. These patients, for whom a diagnosis of aplastic anemia had previously been confirmed, suddenly developed profound or complete hearing loss accompanied by tinnitus and severe vertigo. In addition to erythrocytopenia and thrombocytopenia, serial hematological examinations revealed a marked drop in the platelet count prior to or just at the time of the acute episode of hearing loss. The prognosis for hearing recovery was poor in each patient. These findings suggest that intracochlear hemorrhage could be a mechanism underlying the sudden sensorineural hearing loss in these patients.

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Endoscopic diagnosis of idiopathic perilymphatic fistula

Ogawa Kaoru, Kanzaki Jin, Ogawa Shigeo, Tsuchihashi Nobuaki, Inoue Yasuhiro, Yamamoto Minako

Acta Oto-Laryngologica 114 ( S514 ) 63 - 65 1994

ISSN 0001-6489

The usefulness of endoscopic examination for the diagnosis of idiopathic perilymphatic fistula (IPLF) was investigated. Eight patients presenting with unilateral sensorineural hearing loss and vertigo underwent endoscopic examination by the transtubal or transtympanic approach. In 5 out of the 8 patients, transtubal endoscopy was carried out using a superfine flexible endoscope. With this approach, no abnormal findings were visualized. A perilymphatic leak from the round window was observed in 2 patients by means of transtympanic examination using a needle scope. These findings were confirmed in both patients by microscopic observation during tympanotomy. In one patient who was finally diagnosed with IPLF, the transtympanic endoscopy failed to detect perilymphatic leakage. Although incision of the tympanic membrane is necessary for the examination, transtympanic endoscopy is useful for the diagnosis of IPLF. Further improvement of the superfine flexible fiberscope is necessary before transtubal observation of the tympanic cavity can be effectively conducted.

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Hearing recovery and vestibular symptoms in patients with sudden deafness and profound hearing loss

Yamamoto Minako, Kanzaki Jin, Ogawa Kaoru, Inoue Yasuhiro, Ikeda Shunya

Acta Oto-Laryngologica 114 ( S514 ) 41 - 44 1994

ISSN 0001-6489

Audiometric data from 76 patients with unilateral sudden deafness and hearing loss of 80 dB or more were studied to statistically assess the relationship between vestibular findings (vertigo and/or dizziness, nystagmus, canal paresis) and hearing recovery in various frequency ranges. Hearing recovery in patients with vertigo and/or dizziness (V(+ was much poorer than in patients without such findings (V(-)). Concerning hearing recovery in the high frequency range, a significant statistical difference was evident between the V(+ and V(-) group. There were no statistically significant differences in hearing recovery between patients with spontaneous nystagmus or canal paresis and those without.

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Effect of aging on myo-inositol and phosphoinositide metabolism in the cochlear and vestibular sensory epithelia of the rat

Ogawa Kaoru, McLaren John, Schacht Jochen

Hearing Research 73 ( 2 ) 155 - 162 1994

ISSN 0378-5955

Neurotransmission and transmembrane signaling are among the cellular mechanisms affected in the aging nervous system. In the inner ear, the phosphoinositide second messenger cascade is of particular interest as a target of the aging process. In both the cochlear (CSE) and vestibular sensory epithelia (VSE), the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PtdInsP₂) to the second messenger inositol 1,4,5-trisphosphate (InsP₃) is coupled to muscarinic cholinergic and P_2y purinergic receptors and may be linked to calcium homeostasis. The present study compared the turnover of phosphoinositides (PtdlnsPs), receptor-mediated release of inositol phosphates (InsPs), and concentrations of endogenous myo-inositol in the CSE and VSE of young (3 months) and aged (24 months) Fischer-344 rats. In the aged rat, there was a significant increase in [³H]inositol incorporation (per mass of protein) into PtdlnsPs plus InsPs in both sensory epithelia while the protein content remained unchanged. In contrast, no age-dependent differences were found when pre-labeled [³H]PtdInsPs were 'chased' with non-radiolabeled myo-inositol indicating that the turnover of these lipids was unaffected. The cholinergic receptor agonist carbamylcholine and the P₂ purinergic receptor agonist adenosine 5′-O-(3-thiotriphosphate) stimulated the release of [³H]InsPs two- to six-fold in both organs. This agonist-stimulated release of [³H]InsPs (per mass of protein) was significantly higher in aged animals. However, when the same stimulation was expressed as per cent of control values, there was no age-dependent difference. Finally, the concentration of endogenous myo-inositol decreased by 44% in the aged CSE and by 24% in the aged VSE. In contrast, levels of added myo-[³H]inositol were higher in aged tissues. These results suggest that the increased labeling of PtdlnsPs and InsPs in the aged CSE and VSE is a consequence of the increased specific radioactivity of the myo-[³H]inositol precursor pool. The activity of the phosphoinositide second messenger pathway thus appears unchanged. However, a decreased myo-inositol content may contribute to age-dependent pathology in these tissues, myo-inositol is an organic osmolyte and volume regulator. Changes in osmotic pressure or turgor of hair cells could alter micromechanical coupling on the basilar membrane and vestibular epithelium causing pathophysiological changes in sensory transduction.

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