Nobuhiro Nishiyama

Long-term complications after cochlear implantation

OBJECTIVE Cochlear 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. METHODS A 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. RESULTS Major 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. CONCLUSION Many 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.

Bilateral progressive hearing loss and vestibular dysfunction with inner ear antibodies

Autoimmune inner ear disease (AIED) is a clinical syndrome of uncertain etiology. We present the neuro-otological findings of 2 cases of bilateral hearing loss, dizziness and the antibody profiles of the inner ears. Case 1 had bilateral progressive hearing loss, vestibular dysfunction and abnormal eye movement as the disease progressed. She had inner ear antibodies against 42 and 58kDa protein antigency on Western blot immune assay, and responded to glycocorticosteroid but not to immunosuppressant treatment. Intratympanic steroid injection temporally eliminated her symptoms. However, she developed idiopathic Cushings syndrome and underwent labyrinthectomy. Case 2 became deaf as a teenager and experienced dizziness 10 years after becoming deaf. He reacted strongly to 68kDa protein and was a good responder to immunosuppressant with steroid. As we still lack a definitive diagnostic test for AIED, careful observation of the clinical course is critical for differential diagnosis regarding the bilateral progressive hearing loss.

A case of laryngeal aspergillosis following radiation therapy

Primary laryngeal aspergillosis is extremely rare. It is commonly seen as a part of a systemic infection involving the respiratory system in an immunocompromised host. Differential diagnosis is important, as the clinical symptoms are similar to those of malignant laryngeal disease. We describe a 73-year-old man with a history of hoarseness. He had a history of radiotherapy for laryngeal squamous cell carcinoma and had a history of diabetes. Direct laryngoscope and biopsy confirmed the diagnosis of aspergillus. We cauterized the lesion with a CO(2) laser. In the present case, irradiation seemed to have played a more important role in the onset of this disease rather than diabetes.

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.

POU4F3 mutation screening in Japanese hearing loss patients: Massively parallel DNA sequencing-based analysis identified novel variants associated with autosomal dominant hearing loss

A variant in a transcription factor gene, POU4F3, is responsible for autosomal dominant nonsyndromic hereditary hearing loss, DFNA15. To date, 14 variants, including a whole deletion of POU4F3, have been reported to cause HL in various ethnic groups. In the present study, genetic screening for POU4F3 variants was carried out for a large series of Japanese hearing loss (HL) patients to clarify the prevalence and clinical characteristics of DFNA15 in the Japanese population. Massively parallel DNA sequencing of 68 target candidate genes was utilized in 2,549 unrelated Japanese HL patients (probands) to identify genomic variations responsible for HL. The detailed clinical features in patients with POU4F3 variants were collected from medical charts and analyzed. Novel 12 POU4F3 likely pathogenic variants (six missense variants, three frameshift variants, and three nonsense variants) were successfully identified in 15 probands (2.5%) among 602 families exhibiting autosomal dominant HL, whereas no variants were detected in the other 1,947 probands with autosomal recessive or inheritance pattern unknown HL. To obtain the audiovestibular configuration of the patients harboring POU4F3 variants, we collected audiograms and vestibular symptoms of the probands and their affected family members. Audiovestibular phenotypes in a total of 24 individuals from the 15 families possessing variants were characterized by progressive HL, with a large variation in the onset age and severity with or without vestibular symptoms observed. Pure-tone audiograms indicated the most prevalent configuration as mid-frequency HL type followed by high-frequency HL type, with asymmetry observed in approximately 20% of affected individuals. Analysis of the relationship between age and pure-tone average suggested that individuals with truncating variants showed earlier onset and slower progression of HL than did those with non-truncating variants. The present study showed that variants in POU4F3 were a common cause of autosomal dominant HL.

Intermittent positional downbeat nystagmus of cervical origin

Intermittent positional down beat nystagmus (p-DBN) is rare. We describe an unusual case of intermittent p-DBN which was induced by rotation, anteflexion, and lateral flexion of the neck. A 59-year-old man complained of loss of consciousness and lightheadedness. Positional testing revealed the p-DBN. The evoked p-DBN had latency and the patient had a feeling of passing out while the p-DBN was present. There were no abnormal findings in the vestibular functional examinations. Findings of the MRI were negative. MRA revealed no stenosis of the vertebral artery bilaterally, but there was an anatomical difference. The p-DBN characteristics were documented by electronystagmography during the positional test. The p-DBN lasted intermittently while maintaining the provoking position. It was found that p-DBN occurred with not only the rotation of the neck, but also in the anteflexion and lateral flexion of the neck. There was no stenosis of the vertebral artery (VA) on angiography, but we speculated that the cause of the p-DBN was the VA occlusion due to rotation, anteflexion, and lateral flexion of the neck.

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

OBJECTIVE This 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. METHODS We 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. RESULTS The 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. CONCLUSION The 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.

Simultaneous, laser-sintered, three-dimensional modelling of bony structures and soft tissue for surgical navigation of extended cholesteatoma

AIM To examine the usefulness of a three-dimensional model for surgical navigation of cholesteatoma. MATERIALS AND METHOD A three-dimensional model was prototyped using selective laser sintering. Based on detailed computed tomography data, powder layers were laser-fused and accumulated to create a three-dimensional structure. The computed tomography threshold was adjusted to simultaneously replicate bony structures and soft tissues. RESULTS The cholesteatoma, major vessels and bony structures were well replicated. This laser-sintered model was used to aid surgery for recurrent cholesteatoma. The cholesteatoma, which extended from the hypotympanum through the styloid process sheath and the internal carotid artery sheath, was removed safely via a minimal skin incision. CONCLUSION The laser-sintered model was useful for surgical planning and navigation in a cholesteatoma case involving complex bony structures and soft tissue.