Ryosei Minoda

Auditory hair cell replacement and hearing improvement by Atoh1 gene therapy in deaf mammals

In the mammalian auditory system, sensory cell loss resulting from aging, ototoxic drugs, infections, overstimulation and other causes is irreversible and leads to permanent sensorineural hearing loss. To restore hearing, it is necessary to generate new functional hair cells. One potential way to regenerate hair cells is to induce a phenotypic transdifferentiation of nonsensory cells that remain in the deaf cochlea. Here we report that Atoh1, a gene also known as Math1 encoding a basic helix-loop-helix transcription factor and key regulator of hair cell development, induces regeneration of hair cells and substantially improves hearing thresholds in the mature deaf inner ear after delivery to nonsensory cells through adenovectors. This is the first demonstration of cellular and functional repair in the organ of Corti of a mature deaf mammal. The data suggest a new therapeutic approach based on expressing crucial developmental genes for cellular and functional restoration in the damaged auditory epithelium and other sensory systems.

Causes of recurrent laryngeal nerve paralysis

OBJECTIVE Persistent hoarseness due to recurrent laryngeal nerve paralysis (RLNP) reduces the quality of life unless it is adequately treated. This study examined the indications for phonosurgical intervention in patients with RLNP. MATERIALS AND METHODS The medical records of the Ehime University Hospital, Ehime, Japan, from October 1976 until December 1997 were reviewed retrospectively to identify patients with RLNP. The data collected included age, gender, paralyzed side, and cause of paralysis. RESULTS Four hundred and sixty-six patients with RLNP were identified: 262 males and 204 females. Unilateral RLNP was present in 422 patients, while 44 presented with bilateral RLNP. The incidence was relatively high in the 7th and 8th decades, and was twice as high in male patients as in female patients. The 466 patients were divided into 2 groups: Group 1 included 225 patients seen before January 1987, and Group 2 included 241 patients seen after this date. The number of patients with postoperative RLNP was significantly higher in Group 2 (124 of 239 patients) than in Group 1 (65 of 227 patients) (P<0.05). Surgery for cardiovascular disease, esophageal cancer, and skull base and thyroid gland tumors contributed to this increased incidence of postoperative RLNP. CONCLUSIONS Patients with persistent unilateral RLNP require appropriate treatment for hoarseness, regardless of its cause. Since the incidence of RLNP related to surgery was significantly increased in Group 2, phonosurgery has become more important for improving the quality of life of these patients.

Manipulating cell cycle regulation in the mature cochlea

Sensorineural hearing loss, which is often caused by degeneration of hair cells in the auditory epithelium, is permanent because lost hair cells are not replaced. Several conceptual approaches can be used to place new hair cells in the auditory epithelium. One possibility is to enhance proliferation of non-sensory cells that remain in the deaf ear and induce transdifferentiation of some of these cells into the hair cell phenotype. Several genes, including p27(Kip1), have been shown to regulate proliferation and differentiation in the developing auditory epithelium. The role of p27(Kip1) in the mature ear is not well characterized. We now show that p27(Kip1) is present in the nuclei of non-sensory cells of the mature auditory epithelium. We determined that forced expression of Skp2 using a recombinant adenovirus vector, resulted in presence of BrdU-positive cells in the auditory epithelium. When SKP2 over-expression was combined with forced expression of Atoh1, ectopic hair cells were found in the auditory epithelium in greater numbers than were seen with Atoh1 alone. Skp2 over-expression alone did not result in ectopic hair cells. These findings suggest that the p27(Kip1) protein remains in the mature auditory epithelium and therefore p27(Kip1) can serve as a target for gene manipulation. The data also suggest that induced proliferation, by itself, does not generate new hair cells in the cochlea.

Mouse Otocyst Transuterine Gene Transfer Restores Hearing in Mice With Connexin 30 Deletion-associated Hearing Loss

Although numerous causative genes for hereditary hearing loss have been identified, there are no fundamental treatments for this condition. Herein, we describe a novel potential treatment for genetic hearing loss. Because mutations or deletions in the connexin (Cx) genes are common causes of profound congenital hearing loss in both humans and mice, we investigated whether gene supplementation therapy using the wild-type Cx gene could cure hearing loss. We first generated inner ear-specific connexin 30 (Cx30)-deficient mice via the transuterine transfer of Cx30-targeted short hairpin RNA (shRNA-Cx30) into otocysts. The inner ear-specific Cx30-deficient mice mimicked homozygous Cx30-deficient mice both histologically and physiologically. Subsequently, we cotransfected the shRNA-Cx30 and the wild-type Cx30 gene. The cotransfected mice exhibited Cx30 expression in the cochleae and displayed normal auditory functions. Next, we performed the transuterine transfer of the wild-type Cx30 gene into the otocysts of homozygous Cx30-deficient mice, thereby rescuing the lack of Cx30 expression in the cochleae and restoring auditory functioning. These results demonstrate that supplementation therapy with wild-type genes can restore postnatal auditory functioning. Moreover, this is the first report to show that Cx-related genetic hearing loss is treatable by in vivo gene therapy.

Effects of type II thyroplasty on adductor spasmodic dysphonia

Objectives: Type II thyroplasty, or laryngeal framework surgery, is based on the hypothesis that the effect of adductor spasmodic dysphonia (AdSD) on the voice is due to excessively tight closure of the glottis, hampering phonation. Most of the previous, partially effective treatments have aimed to relieve this tight closure, including recurrent laryngeal nerve section or avulsion, extirpation of the adductor muscle, and botulinum toxin injection, which is currently the most popular. The aim of this study was to assess the effects of type II thyroplasty on aerodynamic and acoustic findings in patients with AdSD. Study Design: Case series. Setting: University hospital. Subjects and Methods: Ten patients with AdSD underwent type II thyroplasty between August 2006 and December 2008. Aerodynamic and acoustic analyses were performed prior to and six months after surgery. Mean flow rates (MFRs) and voice efficiency were evaluated with a phonation analyzer. Jitter, shimmer, the harmonics-to-noise ratio (HNR), standard deviation of the fundamental frequency (SDF0), and degree of voice breaks (DVB) were measured from each subjects longest sustained phonation sample of the vowel /a/. Results: Voice efficiency improved significantly after surgery. No significant difference was found in the MFRs between before and after surgery. Jitter, shimmer, HNR, SDF0, and DVB improved significantly after surgery. Conclusions: Treatment of AdSD with type II thyroplasty significantly improved aerodynamic and acoustic findings. The results of this study suggest that type II thyroplasty provides relief from voice strangulation in patients with AdSD.

The Role of Immediate Recurrent Laryngeal Nerve Reconstruction for Thyroid Cancer Surgery

Unilateral vocal fold paralysis (UVFP) is one of the most serious problems in conducting surgery for thyroid cancer. Different treatments are available for the management of UVFP including intracordal injection, type I thyroplasty, arytenoid adduction, and laryngeal reinnervations. The effects of immediate recurrent laryngeal nerve (RLN) reconstruction during thyroid cancer surgery with or without UVFP before the surgery were evaluated with videostroboscopic, aerodynamic, and perceptual analyses. All subjects experienced postoperative improvements in voice quality. Particularly, aerodynamic analysis showed that the values for all patients entered normal ranges in both patients with and without UVFP before surgery. Immediate RLN reconstruction has the potential to restore a normal or near-normal voice by returning thyroarytenoid muscle tone and bulk seen with vocal fold denervation. Immediate RLN reconstruction is an efficient and effective approach to the management of RLN resection during surgery for thyroid cancer.

Preliminary experience with β-tricalcium phosphate for use in mastoid cavity obliteration after mastoidectomy

Objective: To examine the efficacy and safety of mastoid cavity obliteration using highly purified β-tricalcium phosphate (β-TCP) after mastoidectomy in middle ear surgery. Patients: Thirteen patients with cholesteatoma invading the mastoid cavity or showing severe pathologic changes in the mastoid cavity. Intervention: Twelve patients underwent mastoid obliteration with highly purified β-TCP during the first- and/or second-stage operation of a 2-stage canal-up operation: 5 patients during the first and second stages, and 7 patients during the second stage only. One patient with cholesteatoma underwent mastoid obliteration with highly purified β-TCP during a 1-stage canal-up operation. In total, β-TCP was applied in 18 ear operations. Main Outcome Measures: All patients underwent multislice computed tomography (CT) before and after surgery to assess the condition of the middle ear. The amount of residual β-TCP granules in the mastoid cavity was assessed using the following granular shadow grading scale: Grade 0, no granular shadow in the mastoid cavity; Grade 1, residual granular shadows in part of the mastoid cavity; and Grade 2, granular shadows in most of the mastoid cavity. To assess any harmful effect of β-TCP implanted in the mastoid cavity, continuous postoperative discharge and delayed wound healing were recorded. In addition, the bone conduction threshold was assessed using pure-tone audiometry, and the patients were asked whether they experienced vertigo or dizziness during the postoperative follow-up. Results: All the patients who underwent multislice CT less than 11.4 months after mastoid cavity obliteration with β-TCP were Grade 2 on the granular shadow grading scale, whereas all those who underwent multislice CT more than 53.8 months after mastoid obliteration were Grade 0. No patient had continuous postoperative discharge, delayed wound healing, or extrusion of β-TCP granules. No patient showed deterioration of the bone conduction threshold more than 10 dB after mastoid cavity obliteration with highly purified β-TCP or complained of postoperative vertigo or dizziness. Conclusion: Highly purified β-TCP may be safe and reliable for mastoid obliteration. Highly purified β-TCP may also be useful in other surgical procedures, including posterior wall reconstruction of the external auditory canal and scutum plasty.

Long-term Voice Handicap Index after type II thyroplasty using titanium bridges for adductor spasmodic dysphonia

OBJECTIVES To determine the long-term functional outcomes of type II thyroplasty using titanium bridges for adductor spasmodic dysphonia (AdSD) by perceptual analysis using the Voice Handicap Index-10 (VHI-10) and by acoustic analysis. METHODS Fifteen patients with AdSD underwent type II thyroplasty using titanium brides between August 2006 and February 2011. VHI-10 scores, a patient-based survey that quantifies a patients perception of his or her vocal handicap, were determined before and at least 2 years after surgery. Concurrent with the VHI-10 evaluation, acoustic parameters were assessed, including jitter, shimmer, harmonic-to-noise ratio (HNR), standard deviation of F0 (SDF0), and degree of voice breaks (DVB). RESULTS The average follow-up interval was 30.1 months. No patient had strangulation of the voice, and all were satisfied with the voice postoperatively. In the perceptual analysis, the mean VHI-10 score improved significantly, from 26.7 to 4.1 two years after surgery. All patients had significantly improved each score of three different aspects of VHI-10, representing improved functional, physical, and emotional well-being. All acoustic parameters improved significantly 2 years after surgery. CONCLUSIONS The treatment of AdSD with type II thyroplasty significantly improved the voice-related quality of life and acoustic parameters 2 years after surgery. The results of the study suggest that type II thyroplasty using titanium bridges provides long-term relief of vocal symptoms in patients with AdSD.

Diffusion Tensor Tractography in the Head-and-Neck Region Using a Clinical 3-T MR Scanner

RATIONALE AND OBJECTIVES Diffusion tensor tractography (DTT) for neural fibers of the head-and-neck region at 3T has not been reported. The purpose of this study was to evaluate the feasibility of using DTT for visualizing neural fibers in the head-and-neck region at 3T and to explore the use of this method in patients with head-and-neck mass lesions. MATERIALS AND METHODS Using a 3T scanner, we obtained magnetic resonance images of the head and neck region in 5 healthy volunteers and 5 patients with head and neck mass lesions. All subjects underwent anatomic T1-weighted and diffusion-tensor imaging using a sequence with six motion-probing gradient orientations, a b value of 800 second/mm(2), and a 128 x 128 pixel matrix. Fiber tracking was with the continuous tracking method. Different postprocessing parameters were investigated to optimize fiber density detection and minimize noise. In five patients with head-and-neck mass lesions, comparison of tractography results and operative findings with regards to mass and nerve relationship was also performed by two observers. RESULTS Using the two regions-of-interest method, the greatest fiber density of presumed inferior alveolar nerves was depicted at a maximum angle of 40 degrees and a minimum fiber length of 10 mm. DTT was successfully depicted in all 5 patients. In 4 patients, the relationship between DTT and operative findings was coincided or similar. The interobserver agreement was good. CONCLUSIONS DTT of the neural fibers in the head and neck region is feasible using a clinical 3T magnetic resonance scanner. Data from a small number of patients with head-and-neck lesions show good agreement between tractography and operative results.

Efficacy of mastoid cortex plasty for middle ear aeration in intact canal wall tympanoplasty for cholesteatoma.

Objective To determine the effect of closing the bone defect of the mastoid cortex using bone pate after mastoidectomy (mastoid cortex plasty) during the first-stage operation for the restoration of the mastoid cavity aeration. Study Design This was a prospective study. Setting Tertiary medical center. Patients Thirty-five patients with cholesteatoma invading the mastoid cavity. Intervention Seventeen patients received mastoid cortex plasty with scutum plasty and insertion of a Silastic sheet after removal of the cholesteatoma using a combined approach during the first-stage operation. The 18 control patients received only scutum plasty with the insertion of a Silastic sheet without mastoid cortex plasty during the first-stage operation. Main Outcome Measures The restoration of the middle ear aeration was assessed with high-resolution computed tomography before both the first-stage operation and the second-stage operation. Results The range of middle ear aeration ameliorated significantly whether or not mastoid cortex plasty was performed. Scutum plasty with the insertion of a Silastic sheet without mastoid cortex plasty was significantly effective only for the amelioration of the epitympanum aeration. Mastoid cortex plasty with scutum plasty with the insertion of a Silastic sheet was significantly effective for the amelioration of the epitympanum and also the mastoid cavity aeration. In both groups, before the first-stage operation, approximately 70% of the patients had good mesotympanum aeration, and the mesotympanum aeration ameliorated further after the first-stage operation, although this amelioration was not significant. Conclusions Mastoid cortex plasty is statistically effective for the amelioration of mastoid cavity aeration after the first-stage operation.