Hidemi Miyazaki

Neuro‐otologic Surgery through Minimally Invasive Retrosigmoid Approach: Endoscope Assisted Microvascular Decompression, Vestibular Neurotomy, and Tumor Removal

Objectives: The objective of this study was to describe and evaluate the efficacy of the endoscope assisted minimally invasive retrosigmoid approach.

Molecular biological diagnosis of congenital and acquired cholesteatoma on the basis of differences in telomere length.

Objective To establish a molecular biological basis for differentiation of congenital and acquired cholesteatoma.

A Study on Epidermal Proliferation Ability in Cholesteatoma

With the objective of estimating proliferation ability of epidermis of middle ear cholesteatoma, the difference in proliferating cell nuclear antigen (PCNA) staining between the skin of the bone region of the external ear canal (control skin) and cholesteatoma epidermis and the effects on PCNA staining of subepidermal inflammatory cell infiltration of cholesteatoma were immunohistochemically studied using an antibody against PCNA. Transforming growth factor‐α (TGF‐α) is known to promote epidermal proliferation based on autocrine mechanism. But it is not clear that cholesteatoma epidermis is actually in the state of hyperproliferation under the effect of this growth factor. To estimate the effect of TGF‐α on epidermal proliferation ability, the authors compared the location of PCNA and TGF‐α in the same specimen. Unlike the control skin, not only epidermal basal cell layer and suprabasal cell layer, but also more superior layers were found to have high levels of PCNA staining in the epidermis of cholesteatoma. However, in the same cholesteatoma epidermal tissue, the PCNA staining was varied and the difference was ascribable to subepidermal cell inflammation. It appeared that the proliferation ability was high in regions where subepidermal inflammatory cell infiltration was severe. These differences in microenvironment are inferred to greatly affect proliferation ability of cholesteatoma epidermis.

Roles of cytokines and cell cycle regulating substances in proliferation of cholesteatoma epithelium.

Objectives: It can be surmised that the cell cycle must be involved in cell proliferation of the epithelium of middle ear cholesteatoma. Thus a comparative study was conducted of the levels of expression of cyclin‐dependent kinase 2 (cdk2) and cyclin‐dependent kinase 4 (cdk4)—substances known to be involved in the cell cycle—in cholesteatoma epithelium and the normal epithelium of the bony region of the external ear canal. In addition, it has been reported that the expression of cytokines in the epithelium is accelerated in response to subepithelial inflammation. This suggests that an interaction between the epithelium and subepithelium, which is subject to paracrine regulation, is deeply involved in epithelial proliferation. Accordingly, attention was focused on interleukin−1α (IL‐1α) and keratinocyte growth factor (KGF), cytokines which are found in the subepithelium, and experiments were conducted to elucidate their effects on the expression of the substances known to be involved in the cell cycle. Methods: The expressions of cdk2 and cdk4 in the cholesteatoma epithelium and external ear canal epithelium were investigated by an immunohistochemical technique. In addition, cultured human keratinocytes were grown in medium containing IL‐1α or KGF at concentrations of 0, 20, and 100 ng/mL, and the differences in the expression of cdk2 and cdk4 were investigated and compared by Western blot analysis. Results: In the cholesteatoma epithelium specimens, cdk2 and cdk4 were observed to be expressed in the basal and parabasal layers and in the upper layer (prickle layer and granular layer). Their expression tended to be increased compared with their expression in the normal external ear canal epithelium, and this tendency was marked in subepithelial sites showing severe inflammation. In addition, exposure of cultured human keratinocytes to IL‐1α or KGF resulted in accelerated expression of both cdk2 and cdk4, and this was especially striking in the case of addition of KGF. Conclusion: It can be surmised that, in cholesteatoma, accelerated expression of IL‐1α and KGF by inflammatory cells at subepithelial sites of inflammation leads to upregulation of cdk2 and cdk4 in epithelial cells and to cell proliferation. It was concluded that this is at least one sequence of events involved in the mechanism causing epithelial proliferation in cholesteatoma.

Routes, dynamics, and correlates of cochlear inflammation in terminal and recovering experimental meningitis

To examine the routes, dynamics and correlates of cochlear inflammation in meningitis to provide information on the pathogenesis of the associated hearing loss and indications for rational pharmacotherapeutical intervention.

Improved preservation of function during acoustic neuroma surgery

OBJECT Restoration of cranial nerve functions during acoustic neuroma (AN) surgery is crucial for good outcome. The effects of minimizing the injury period and maximizing the recuperation period were investigated in 89 patients who consecutively underwent retrosigmoid unilateral AN surgery. METHODS Cochlear nerve and facial nerve functions were evaluated during AN surgery by use of continuous auditory evoked dorsal cochlear nucleus action potential monitoring and facial nerve root exit zone-elicited compound muscle action potential monitoring, respectively. Factors affecting preservation of function at the same (preoperative) grade were analyzed. RESULTS A total of 23 patients underwent standard treatment and investigation of the monitoring threshold for preservation of function; another 66 patients underwent extended recuperation treatment and assessment of its effect on recovery of nerve function. Both types of final action potential monitoring response and extended recuperation treatment were associated with preservation of function at the same grade. CONCLUSIONS Preservation of function was significantly better for patients who received extended recuperation treatment.

Terminal Differentiation of Epithelial Cells in Middle Ear Cholesteatoma: Investigation of Patterns of Expression of Protein Kinase C-δ and Protein Kinase C-η

Objectives: The objective of this study was to elucidate the differentiation mechanism of keratinocytes in cholesteatoma.

Endoscope-assisted surgery via the middle cranial fossa approach for a petrous cholesteatoma.

OBJECTIVE Surgical approaches to petrous cholesteatomas are the translabyrinthine-transcochlear approach, partial labyrinthectomy, and the middle cranial fossa approach. Selection of surgical approach is determined by region of cholesteatoma in the petrous bone as well as preoperative status of hearing and facial nerve function. The middle cranial fossa approach is the best approach for patient having good preoperative hearing and facial nerve function. However, application of this approach is limited for patients having relatively small petrous cholesteatomas, and sometimes difficult for patients in whom inner ear function is preserved but a cholesteatoma surrounds whole cochlea and extends to lower part of the labyrinth. In such case, we performed endoscope-assisted surgery via the middle cranial fossa approach to preserve cochlear and its function. METHODS 30 degrees and 70 degrees rigid endoscopes were used for the operation via the middle cranial fossa. RESULTS The inferior surface of the cochlea and the region around the internal carotid artery could be well visualized by use of endoscopy, and we succeeded in removal of petrous cholesteatoma surrounding the cochlea completely with preserving preoperative hearing. CONCLUSION Endoscope-assisted surgical technique that allowed safe and complete removal of a cholesteatoma extended inferior surface of coclear and around carotid artery in the petrous.

Objective and Subjective Outcome of a New Transcutaneous Bone Conduction Hearing Device: Half-year Follow-up of the First 12 Nordic Implantations.

Objective: To examine the objective and subjective outcome of a new transcutaneous bone conduction hearing device. Study Design: Prospective, consecutive case series. Patients: Twelve patients were implanted. Eight patients had a conductive/mixed (con/mix) hearing loss. Four had single sided deafness. Main Outcome Measures: At half-year follow-up, aided and unaided sound field hearing was evaluated by 1) warble tone thresholds, 2) pure-tone average (PTA4), 3) speech discrimination score (SDS) in quiet, and 4) speech reception threshold 50% at 70 dB SPL noise level (SRT50%). Subjective outcome was evaluated by three questionnaires: 1) International Outcome Inventory for Hearing Aids, 2) Speech, Spatial and Qualities of Hearing Scale 12, and 3) a questionnaire on frequency and duration of use. Results: No major complications occurred. The mean aided PTA4 was lowered by 23 dB. SDS was increased by 40% at 50 dB, by 34% at 65 dB, and by 12% at 80 dB SPL. SRT50% in noise improved 5.2 dB. 58% of the patients used the device daily and 83% at least 5 days a week. 50% used the device ≥8 hours and 75% ≥ 4 hours a day. Mean International Outcome Inventory for Hearing Aids score was 3.7, corresponding to beneficial outcome. In Speech, Spatial and Qualities of Hearing Scale 12, “quality of hearing” scored especially high. The con/mix hearing loss group showed larger benefit especially in SDS, SRT50% in noise and the subjective evaluations, whereas frequency and duration of use were similar. Conclusion: This study on the first 12 Nordic patients implanted with a new transcutaneous bone conduction hearing device demonstrates significant objective, as well as subjective hearing benefit. Patient satisfaction was high, as was the frequency of use.

Sporadic Endolymphatic Sac Tumor-A Very Rare Cause of Hearing Loss, Tinnitus, and Dizziness

Sporadic endolymphatic sac tumor is a very rare neoplasm. It is low malignant, locally destructive and expansive, but non-metastasizing. The tumor is very rare in the sporadic form, but more often associated with Von Hippel-Lindau disease. A 65-year old man with left sided tinnitus and hearing loss for several months. Audiometry showed an asymmetrical sensory neural hearing loss on the left side up to 60 dB. The speech discrimination score was 46% and stapedial reflexes were absent. Several years earlier, he had suffered from periods of dizziness. Magnetic resonance imaging (MRI) showed a destructive and locally invasive tumor in the peripheral vestibular system expanding into the cerebellopontine angle. Paraganglioma and von Hippel-Lindau`s disease were excluded. Vestibular examination showed no function of vestibular organ left side. The tumor was resected radically by translabyrintine approach. Per-operative freeze-microscopy showed inflammation tissue, whereas subsequent microscopy showed papillary-cystic endolymphatic sac tumor. Endolymphatic sac tumor is a rare neoplasm. The tumor may present with asymmetrically sensory neural hearing loss with or without tinnitus, dizziness and facial nerve paresis. An MRI scan is the appropriate diagnostic tool final dianosis is made by the post-operative histo-pathology. Dizziness can be the first sign of a tumor in this area.