Atsushi Kawano

Rapid prototyping of temporal bone for surgical training and medical education

Objective The skills of ear surgery are best developed by dissecting a temporal bone. However, only a limited number of trainees can be afforded this opportunity because of the scarcity of available bones. The aim of this study was to investigate the validity of a prototype temporal bone model for surgical training and education. Material and Methods A simulated 3D model of a human temporal bone was made using a selective laser sintering method. The powder layers were laser-fused based on detailed CT data and accumulated to create a 3D structure. Conventional surgical instruments were used to dissect the model under a microscope. Results The model was as hard as real bone and surface structures were accurately reproduced. The model could be shaved using a surgical drill, burr and suction irrigator in the same way as a real bone. The malleus and incus were reproduced. The semicircular canals and the oval and round window niches were identified. Cavity structures, such as the semicircular canal, vestibule, antrum and air cells, were filled with powder which had to be removed using a pick and suction irrigator during dissection. A magnified model was useful for educating medical students. Conclusion This prototype 3D model made using selective laser sintering serves as a good educational tool for middle ear surgery.

Long-term complications after cochlear implantation

OBJECTIVEnCochlear implantation has become an effective treatment for many profoundly deaf patients. As with any surgical procedure, a proportion of patients suffer postoperative complications. The aim of this study was to analyze long-term postoperative complications in patients with cochlear implants with a view to improve clinical interventions and propose a consensus for reporting complications.nnnMETHODSnA total of 406 cases received cochlear implants between December 1985 and April 2007 at Tokyo Medical University (TMU) Hospital. We retrospectively reviewed case notes from 366 patients who had undergone cochlear implantation (215 adults and 151 children) after excluding 40 patients of re-implantation including 13 cases implanted initially at other hospitals. Life-threatening, major and minor complications were examined retrospectively.nnnRESULTSnMajor complications occurred following cochlear implantation in 32 patients (8.7%) who had received their initial implant at TMU Hospital. Revision surgery was required for 30 patients. The mean age at implantation was 33 years 6 months (range, 1 year 9 months to 83 years; median, 37 years). The main etiology of deafness was unknown or progressive (113, 52.6%) in adults and congenital (132, 87.4%) in children. The cause of deafness was meningitis in 41 cases (11.2%), and 26 cases (7.1%) were diagnosed with idiopathic sudden deafness. Flap-related problems (including middle ear infection and/or flap necrosis) developed in 13 cases (3.6%), with 12 cases (7 adults, 5 children) requiring re-implantation. Electrode slip-out occurred in 8 patients (7 adults, 1 child). All adult cases in whom electrodes slipped out underwent implantation before 1994, while the child (1 pediatric case) was operated in 2003. All cases required re-implantation and most cochlear implantations were performed using the modified split-bridge technique after 1997. Six patients (4 adults, 2 children) experienced device failure. Four patients experienced electrode problems. Non-surgical major complications included 1 patient with permanent facial nerve paralysis as a result of thermal injury in 1995. The total number of minor medical and surgical complications was 27, representing 7.4% of all operations.nnnCONCLUSIONnMany cases of major complications, including electrode problems and facial paralysis, excluding traumatic device failure were considered avoidable by strict operative and postoperative procedures. Some cases of flap infection and traumatic device failure may not be able to be avoided completely, and every possible care should be taken by implant patients and others involved.

Cochlear implantation in patients with chronic otitis media

OBJECTIVEnPatients with complications of otitis media present a significant challenge to safe cochlear implantation. We describe our experience of cochlear implantation in patients with chronic ear disease, and propose management principles according to the presenting status of the ear.nnnMETHODSnCochlear implantations were performed as treatment for complications of otitis media in seven patients. They consisted of four patients with adhesive otitis media, two patients with an open cavity after surgery for otitis media and one patient with eosinophilic otitis media. The electrodes were inserted by an approach via the external auditory canal in patients with poor growth of the mastoid antrum or adhesion of the tympanum. For the patients with an open cavity, we created a posterior wall for the external auditory canal and perform the mastoid obliteration. Modified Rambos technique with blind sac closure of the external auditory canal was performed for the case of eosinophilic otitis media as a single-stage procedure.nnnRESULTSnThe post-operative courses were good. However, a post-operative infection developed in one patient who had previously undergone radiation therapy following surgical excision of a cerebellar tumor.nnnCONCLUSIONnTranscanal approach is effective in a poorly pneumatized mastoid or severe adhesive otitis media. A decision whether implantation as a single-stage or multiple stages depends on the condition of each cases. But there is a possibility of infection even if we selected a stage operation.

Prevalence of GJB2 causing recessive profound non-syndromic deafness in Japanese children

OBJECTIVEnGJB2 (gap junction protein, beta 2, 26kDa: connexin 26) is a gap junction protein gene that has been implicated in many cases of autosomal recessive non-syndromic deafness. Point and deletion mutations in GJB2 are the most frequent cause of non-syndromic deafness across racial groups. To clarify the relation between profound non-syndromic deafness and GJB2 mutation in Japanese children, we performed genetic testing for GJB2.nnnMETHODSnWe conducted mutation screening employing PCR and direct sequencing for GJB2 in 126 children who had undergone cochlear implantation with congenital deafness.nnnRESULTSnWe detected 10 mutations, including two unreported mutations (p.R32S and p.P225L) in GJB2. We identified the highest-frequency mutation (c.235delC: 44.8%) and other nonsense or truncating mutations, as in previous studies. However, in our research, p.R143W, which is one of the missense mutations, may also show an important correlation with severe deafness.nnnCONCLUSIONnOur results suggest that the frequencies of mutations in GJB2 and GJB6 deletions differ among cohorts. Thus, our report is an important study of GJB2 in Japanese children with profound non-syndromic deafness.

Involvement of the incudostapedial joint anomaly in conductive deafness

Conclusion. The outcome of surgery depends on complexities of middle ear anomalies and definite diagnosis can only be achieved during exploratory tympanotomy. We must be aware that the pathology of the congenital ossicular anomalies is variable and careful surgery is needed for hearing improvement. Objective. This study aimed to investigate congenital ossicular malformation. Subjects and methods. Fifteen cases of ossicular anomalies without external ear malformation were studied. The anomaly of the incus-stapes complex was the most frequent. There were two cases of fused incudostapedial (IS) joint, which is an extremely rare occurrence. Case 1 was a 33-year-old man, in whom otosclerosis was suspected and exploratory tympanotomy was performed. The IS joint was fused, and the stapes was immobile. Small fenestra stapedectomy was performed. In case 2, a 52-year-old woman, otosclerosis was also suspected and exploratory tympanotomy was performed. The IS joint was fused and the incus was fixed. After the long process of the incus was cut, the stapes became mobile. However, since the incus remained immobile, it was removed and was placed on the stapes. In both cases, the hearing improved after surgery. The averaged hearing gain of 15 cases was 28.8 dB.

Cochlear implantation in a patient with Epstein syndrome

Epstein syndrome is a rare disease which is accompanied by nephritis, sensorineural hearing impairment and macrothrombocytopenia. It has been suggested that this syndrome is a hereditary disease associated with mutations in MYH9, which encodes non-muscle myosin heavy chain IIA. We report a case of a patient with Epstein syndrome in whom bilateral profound hearing impairment developed and who had undergone cochlear implantation 9 years previously. Prior to this, the patient showed progressive sensorineural hearing impairment and had become completely deaf by the age of 25. A cochlear implant was successfully used with a speech discrimination score of 98% (sentence test). However, in the present case, peri- and postoperative complications occurred: tympanic perforation remained after a promontory stimulation test, followed by transitory otitis with purulent discharge. Therefore, tympanoplasty was performed simultaneously with cochlear implantation. These complications were considered to be caused by platelet dysfunction and delayed wound healing. Furthermore, cochlear destruction was observed 8 years postoperatively. In Epstein syndrome, the mechanism of osseous change remains uncertain. To the best of our knowledge, this is the first case report of Epstein syndrome in a patient with long-term use of a CI.

The clinical features of patients with the homozygous 235delC and the compound-heterozygous Y136X/G45E of the GJB2 mutations (Connexin 26) in cochlear implant recipients

OBJECTIVEnThis study aimed to investigate the prevalence of GJB2 gene for the 235delC mutations, the clinical features and the outcomes of patients who had undergone cochlear implantation.nnnMETHODSnWe have sequenced the coding region of GJB2 gene for 135 patients with sensorineural deaf from September 2000 to May 2009. Of the 135 patients, the patients with the homozygous 235delC and the compound-heterozygous Y136X/G45E were detected and were investigated clinically.nnnRESULTSnThe GJB2 gene for the 235delC mutations was found in 39 alleles of 270 alleles (14.4%), especially for the homozygous of 235delC was detected in 26 alleles (9.6%), the single heterozygous of 235delC was 1 allele (0.4%), the compound heterozygous of 235delC was found in 12 alleles (4.4%). Of 16 subjects (29 alleles) with the homozygous 235delC and the compound-heterozygous Y136X/G45E, 2 subjects (4 alleles) were found to have complications. All of the subjects were found to show severe hearing loss and some of them have indicated progressive hearing loss. However, they showed better performance regarding the thresholds after implantation. The subjects with complications, although, suggested poorer performance in the auditory speech performance.nnnCONCLUSIONnThe findings of poorer outcomes might depend on complications and brain functions. In addition, considering the blood test parameters, an independent elevated LDH and ChE at diagnosis were found to be associated with hereditary enzymes metabolic disease. Therefore, the value of LDH measurements in patients might be a helpful predictive parameter in hereditary diseases.

Bilateral versus unilateral cochlear implantation in adult listeners: speech-on-speech masking and multitalker localization

Binaural hearing helps normal-hearing listeners localize sound sources and understand speech in noise. However, it is not fully understood how far this is the case for bilateral cochlear implant (CI) users. To determine the potential benefits of bilateral over unilateral CIs, speech comprehension thresholds (SCTs) were measured in seven Japanese bilateral CI recipients using Helen test sentences (translated into Japanese) in a two-talker speech interferer presented from the front (co-located with the target speech), ipsilateral to the first-implanted ear (at +90° or −90°), and spatially symmetric at ±90°. Spatial release from masking was calculated as the difference between co-located and spatially separated SCTs. Localization was assessed in the horizontal plane by presenting either male or female speech or both simultaneously. All measurements were performed bilaterally and unilaterally (with the first implanted ear) inside a loudspeaker array. Both SCTs and spatial release from masking were improved with bilateral CIs, demonstrating mean bilateral benefits of 7.5u2009dB in spatially asymmetric and 3u2009dB in spatially symmetric speech mixture. Localization performance varied strongly between subjects but was clearly improved with bilateral over unilateral CIs with the mean localization error reduced by 27°. Surprisingly, adding a second talker had only a negligible effect on localization.

Speech recognition in bilaterally cochlear implanted adults in Tokyo, Japan

Abstract Introduction: The clinical effects of bilateral cochlear implantation (BCI) include binaural summation and better hearing under noise conditions. This study retrospectively examined the utility of BCI compared to unilateral cochlear implantation (CI) in adults. Patients and methods: We investigated 34 adults who underwent BCI, comparing speech recognition between BCI and first CI under silent and noise conditions. We assessed correlations between speech recognition after first and second CIs, and between the interval from first to second CI surgery and speech recognition of second CI. Results: Word recognition score (WRS) and sentence recognition score (SRS) were significantly better after BCI than after first CI under conditions of silence and noise. No significant correlation was found between speech recognition after first CI and that after second CI, or between inter-implant interval and speech recognition of second CI for either WRS or SRS. Conclusions: The utility of BCI in Japanese patients was shown. Patients have no need to be pessimistic about hearing after the second implantation even if speech recognition after the first implantation is poor. A long interval from first CI does not necessarily contraindicate contralateral implantation in adults.

Stapes fixation accompanied with abnormal facial nerve pathway

The patient was a 52-year-old woman. She had been aware of her bilateral hearing loss since she was 20 years old. The hearing in her left ear started to deteriorate at the age of 49. Pure-tone audiometry showed a bilateral mixed hearing loss. The hearing levels for the right ear and the left ear were 52 dB and 68 dB, respectively. There were no remarkable findings in a computed tomography (CT) scan of the temporal bone. We suspected that she had otosclerosis, and an operation was performed on her left ear. When the incudostapedial joint (I-S joint) was exposed to investigate the movement of the stapes, a soft white band that ran under the superstructure of the stapes was noted. By using a nerve monitoring system, we confirmed that the white band was the bare facial nerve. The ossicular chain was normal, except for a malformed stape due to the facial nerve, and the footplate of the stapes was fixed. Therefore, she was diagnosed as having otosclerosis with an abnormal facial nerve pathway. The malformed superstructure of the stapes was removed carefully. When the ectopic facial nerve was shifted to anteroinferior side, the oval window could be seen. Stapedotomy using a Teflon piston prosthesis was performed with no complications.