Long-term outcome of cochlear implant in patients with chronic otitis media: one-stage surgery is equivalent to two-stage surgery.

This study compared long-term speech performance after cochlear implantation (CI) between surgical strategies in patients with chronic otitis media (COM). Thirty patients with available open-set sentence scores measured more than 2 yr postoperatively were included: 17 who received one-stage surgeries (One-stage group), and the other 13 underwent two-stage surgeries (Two-stage group). Preoperative inflammatory status, intraoperative procedures, postoperative outcomes were compared. Among 17 patients in One-stage group, 12 underwent CI accompanied with the eradication of inflammation; CI without eradicating inflammation was performed on 3 patients; 2 underwent CIs via the transcanal approach. Thirteen patients in Two-stage group received the complete eradication of inflammation as first-stage surgery, and CI was performed as second-stage surgery after a mean interval of 8.2 months. Additional control of inflammation was performed in 2 patients at second-stage surgery for cavity problem and cholesteatoma, respectively. There were 2 cases of electrode exposure as postoperative complication in the two-stage group; new electrode arrays were inserted and covered by local flaps. The open-set sentence scores of Two-stage group were not significantly higher than those of One-stage group at 1, 2, 3, and 5 yr postoperatively. Postoperative long-term speech performance is equivalent when either of two surgical strategies is used to treat appropriately selected candidates.

Audiological and surgical evidence for the presence of a third window effect for the conductive hearing loss in DFNX2 deafness irrespective of types of mutations.

The objective of this study was to clarify the cause of the air-bone gap in incomplete partition (IP) type III cases according to the POU3F4 gene (DFNX2) mutation type. A retrospective analysis of patient medical records was done in a tertiary referral medical center. Five IP type III patients proved to be carrying a mutation in or affecting POU3F4. The hearing and the middle ear status at either exploratory tympanotomy or cochlear implantation from these DFNX2 cases was reviewed. Four of five unrelated IP type III patients harbored a point mutation of POU3F4 and the fifth patient carried a large genomic deletion upstream to POU3F4. Two of the four DFNX2 patients carrying a point mutation had moderate to severe mixed hearing loss with a substantial amount of air-bone gap. These patients underwent exploratory tympanotomy to identify the cause of their hearing loss. The other three patients, including one carrying a large deletion, had profound hearing loss at presentation and received a cochlear implant. In the exploratory tympanotomy group with a substantial amount of air-bone gap and a point mutation (n = 2), one patient had a perfect ossicular chain with normal mobility, a positive ipsilateral stapedial reflex, and a positive round window reflex. In the cochlear implantation group (n = 3), we found a stapes with normal mobility and a positive round window reflex in one patient who harbored a large genomic deletion upstream to POU3F4. We concluded that the probable presence of the third window effect is not limited to the particular type of POU3F4 mutation.

Stage progression of congenital cholesteatoma in children.

This study aimed to investigate the most prevalent stage in each age-group of children with congenital cholesteatoma (CC) and verify the correlation between the stage and the age of the patients for the type of CC ("closed" keratotic cyst and "open" infiltrative types). Patients diagnosed with CC between 2004 and 2009 (n = 156; 116 boys and 40 girls; mean age, 5 years and 5 months; range, 12 months-16 years and 7 months) were enrolled retrospectively. Assessment of stage and type of CC was performed with preoperative high-resolution temporal bone computed tomography and intraoperative findings. The stage of CC was determined using Potsic's staging system classified into four stages according to ossicular involvement and mastoid extension. The patients consisted of groups divided on the basis of a 2-year interval. The prevalence of stage I began to decline from the age-group of 1-2 years. In contrast, the prevalence of stages III increased from the age-group of 3-4 years and that of stage IV from the age-group 5-6 years. The prevalence of "open" infiltrative type CC increased from approximately the age of 7 years, thus showing some correlation with age but not with stage. The prevalence of CC with the advanced stage increased since the age of 2 years. Therefore, the importance of early diagnosis and treatment of CC should be more emphasized.

Management of complications in cochlear implantation.

CONCLUSION: Cochlear implantation (CI) remains a safe procedure with a low complication rate. Nevertheless, advances in surgical techniques and the optimization of treatment modalities would further reduce complications. OBJECTIVE: To assess the complications of CI and describe the management of each complication encountered at our hospital. PATIENTS AND METHODS: This study involved 720 patients that underwent implantation from November 1988 through April 2007. Mean age at implantation was 13.6 years (range 12 months to 83 years). Patients were followed up regularly with a mean follow-up of 42 months (range 4-81 months). RESULTS: No death was attributed to device implantation. Major complications included: device failure in 12 patients, misplaced electrodes in 4, hematoma in 3, flap necrosis in 3, magnet displacement in 2, facial nerve twitching in 2, electrode exposure in 2, external auditory canal keratoma in 1, immediate facial nerve paralysis in 1, and skin flap irritation due to the suture material in 1. The overall major complication rate was 4.2% (30/720), and there were 37 minor complications (5.1%), which were resolved by conservative treatment or minor intervention. Minor complications included temporary vertigo in 17 patients, facial twitching in 11, hematoma in 4, subcutaneous emphysema in 3, and temporary facial nerve paralysis in 2.

Changes in P2Y4 receptor expression in rat cochlear outer sulcus cells during development.

Extracellular adenosine triphosphate (ATP) released from cellular sources plays an important role in variety of the cochlear physiologic processes. The primary purinergic receptor subtype in the cochlea is the P2X2 receptor, which is a subtype of P2X receptor. This receptor appears to mediate a protective decrease in the electrical driving force in response to acoustic overstimulation. Outer sulcus cells (OSCs) in the cochlear lateral wall appear to maintain an adequate K+ concentration in the cochlear endolymph in response to varying intensities of auditory stimulation. However, little is known about developing OSCs. The purpose of this study was to investigate subtypes of purinergic receptors in developing rat OSCs using a voltage-sensitive vibrating probe. Results showed that only two P2 receptors (P2Y4 and P2X2) contributed to the regulation of short circuit currents in neonatal OSCs. ATP increased cation absorption via apical nonselective cation channels after activating P2Y4 receptors in early neonatal OSCs. P2Y4 expression rapidly declined postnatally and reached near adult levels on postnatal day 14. P2X2 was co-expressed with P2Y4 in early neonatal OSCs. Temporal changes in P2Y4 during OSC development might be involved in the establishment of the endolymphatic ion composition needed for normal auditory transduction and/or specific cellular differentiation.

Gene expression and plasticity in the rat auditory cortex after bilateral cochlear ablation.

CONCLUSION: The plastic changes in the auditory cortex after bilateral cochlear ablation are related to the immediate early genes as well as the neural plasticity-related genes. In addition, cross-modal plasticity may play an important role in the early changes in the auditory cortex after bilateral cochlear ablation. OBJECTIVES: The purpose of this study was to identify candidate genes involved in the normal development of primary auditory cortex during the critical period as well as those genes specifically modulated under conditions of sensory deafferentation by bilateral cochlear ablation. MATERIALS AND METHODS: We produced a bilaterally deaf rat model and used DNA microarray technology to analyze differential gene expression in the primary auditory cortex of bilateral cochlear ablated and sham-operated age-matched control rats. Gene expression in the auditory cortex was compared at 2, 4, and 12 weeks after surgery. For selected genes, the changes in gene expression were confirmed by real-time polymerase chain reaction (PCR). RESULTS: In the cochlear ablation groups, the expression of immediate early genes (Egr1, 2, 3, 4, c-fos, etc.) and neural plasticity-related genes (Arc, Syngr1, Bdnf, etc.) was decreased at 2 weeks and increased at 4 weeks. The expression of neurotransmission-related genes (Gabra5, Chrnb3, Chrne, etc.) was decreased at 12 weeks.

WDR1 expression in the normal and noise-damaged chick vestibule.

Unlike mammals, avian cochlear hair cells can regenerate after acoustic overstimulation. The WDR1 gene is one of the genes suspected to play an important role in this difference. In an earlier study, we found that the WDR1 gene is over-expressed in the chick cochlea after acoustic overstimulation. The aim of this study was to compare the expression of WDR1 before and after acoustic overstimulation in the chick vestibule. Seven-day-old chicks were divided into three groups: normal group, damage group, and regeneration group. The damage and regeneration group was exposed to 120 dB SPL white noise for 5-6 hours. The damage group was euthanized shortly after the impulse, but the regeneration group was allowed to recover for 2 days. The utricle, saccule, and the three ampullae of each semicircular canal were dissected and immunohistochemically stained with anti-WD40 repeat protein 1 antibody. For quantitative analysis, immunoreactive densities were measured and quantitative real-time RT PCR was performed. WD40 repeat protein 1 expression was elevated in all the semicircular canals and utricle, two days after an acoustic overstimulation (P=0.001). WDR1 mRNA expression was 1.34 times higher in the regeneration group compared to the normal group, but it was not statistically significant. Exceptionally, WD40 repeat protein 1 expression did not increase in the saccule of the regeneration group. Elevated WDR1 expression in the avian vestibule may have a role in the hair cell regenerating ability as in the avian cochlea. A similar mechanism of hair cell regeneration may exist in the avian cochlea and vestibule.

Optimal use of CT imaging in pediatric congenital cholesteatoma.

OBJECTIVE: This study aimed to determine the radiation dose of temporal bone computed tomography (TBCT) to detect pediatric congenital cholesteatoma (CC), and suggests strategy for lowering perioperative radiation dose. METHODS: Fifty-three CC patients followed up for more than 12 months after surgery. Perioperative clinical findings and the effective radiation dose (ERD) of TBCT were investigated. Patients' mean age at initial TBCT was 60 months; the mean follow-up period was 43 months. RESULTS: In 33 (62.3%) of 53 patients, only one TBCT was performed postoperatively. Postoperative CT imaging was performed to evaluate before second-stage ossiculoplasty, due to suspicion of CC recurrence on examinations, or as part of follow-up. When TBCT was performed on more than two occasions after surgery as a part of follow-up, there was no difference in the distribution of stage or type of CC compared to patients subjected to TBCT on less than three occasions (p=0.093 and p=0.744, respectively). During the most-recent follow-up of these 53 cases, there was no CC recurrence. The mean ERD of a single TBCT was 1.2mSv, and the mean cumulative ERD of TBCT was 2mSv per patient. CONCLUSION: Mean and cumulative ERD of TBCT performed in CC cases was not too high to consider radiation hazard. However, efforts to minimize the number of CT scans should be taken basically.

Reactive blue 2, an antagonist of rat P2Y4, increases K+ secretion in rat cochlea strial marginal cells.

Extracellular ATP decreases K+ secretion in strial marginal cells via apical P2Y4 receptors. We investigated the effect of reactive blue 2 (RB-2), an antagonist of rat P2Y4, on rat strial marginal cells using a voltage-sensitive vibrating probe. The application of RB-2 increased K+ secretion in a dose-dependent manner, and this increase was characterized as a peak followed by a partial relaxation to a steady-state. Moreover, this response was similar to that caused by 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS). Suramin had no similar effect, except at high concentration. Thus, we tested the effects of these chemicals on P2Y4 receptors in strial marginal cells. Both RB-2 and DIDS had antagonistic activities at P2Y4, and the antagonist potency at P2Y4 paralleled the potency of K+ secretion. Interestingly, 2'- and 3'-O-(4-benzoyl-benzoyl)adenosine 5'-triphosphate (BzATP) exhibited an agonistic effect at P2Y4 receptor, which was blocked by RB-2, but not by pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS). Based on these results, we speculate that direct and/or indirect inhibitory mechanisms between P2Y4 and KENQ1/KCNE1 K+ channels exist in strial marginal cell.

Cochlear implantation in superficial siderosis.

Superficial siderosis (SS) of the central nervous system has been thought to be a rare condition that generates progressive hearing loss, ataxia, pyramidal signs, and dementia. The main cause of hearing loss by SS is thought to be neuronal. Because there is no histopathologic report of the human temporal bone in SS, there is a debate about the possibility of cochlear involvement. We present a 25-year-old man who was investigated for bilateral progressive sensorineural hearing loss and vestibular failure after head trauma. On brain MRI, SS of the central nervous system was detected. Distortion product otoacoustic emission (DPOAE) and auditory brainstem response (ABR) showed no response on both sides. However, integrity of the eighth nerve was proved by the electrical ABR test on the right side and the patient benefited significantly from cochlear implantation. The sensorineural hearing loss in SS seems to be related to cochlear damage as well as neuronal damage. So, cochlear implantation would be a hearing rehabilitation modality for the sensorineural hearing loss caused by SS.

Temporalis myofascial flap coverage for extrusion of internal device after cochlear implantation.

Two pediatric patients with internal device exposure of cochlear implant (CI) were treated successfully using vascularized temporalis myofascial flaps. The visible scarring was minimal, and the CI function was excellent. Although we used temporalis myofascial flaps for late complications of an implanted ear, it can also be used in a primary case to provide flap reinforcement. In conclusion, the temporalis myofascial flap technique is an ultimate surgical option that offers advantages for CI patients with flap-related problems.

Long-term functional and behavioral-emotional outcomes in children with early cochlear implants: Parental testimonies.

OBJECTIVES: (1) To assess the long-term effects of cochlear implantation (CI) on speech perception and school life, and (2) to evaluate behavioral and emotional development, including social skills, post-implantation. METHODS: We telephoned caregivers and asked them a standardized questionnaire. We used the data to explore the daily lives (including school life) of children who had undergone CI before the age of 4 years and who had used the device for >10 years. We also evaluated behavioral/emotional development. RESULTS: Most children used CI devices for virtually all their waking moments and attended mainstream schools. Moreover, more than 75% of them could comprehend common phrases or conversations without lip-reading and carry out a telephone conversation with a person known to them. The mean T-scores for all scales of behavioral/emotional assessment, including those concerning social skills, were within the normal ranges, although scores on the competence scale were lower than those on other scales. CONCLUSIONS: This long-term study of early-CI children shows that CI improves not only speech perception, but also behavioral/emotional development, including social skills.

Incus footplate assembly: Indication and surgical outcome.

OBJECTIVES/HYPOTHESIS: To review surgical findings and hearing outcomes of incus footplate assembly (IFA) for the patients with conductive hearing loss due to missing stapes superstructure with a mobile stapes footplate. STUDY DESIGN: Retrospective case review and survey. METHODS: Pre- and postoperative audiometric data and intraoperative findings were reviewed. Postoperative air-bone gap (ABG) and ABG closure (postoperative air-conduction threshold-preoperative bone-conduction threshold) were analyzed. RESULTS: The causes of missing stapes superstructure and conductive hearing loss were congenital ossicular anomaly (n = 5), chronic otitis media (n = 2), and congenital cholesteatoma (n = 1). The prosthesis was designed to fit between the medial side of the incus and stapes footplate and had a mean length of 3.6 ± 0.5 mm. The mean pre- and postoperative ABG were 38.3 ± 4.8 and 13.3 ± 10.0 dB, respectively. The postoperative ABG at frequencies of 0.25, 0.5, 1.0, 2.0, 3.0, and 4.0 kHz were 20.0 ± 15.4, 16.9 ± 11.9, 16.3 ± 10.3, 10.6 ± 7.3, 12.9 ± 14.0, and 23.1 ± 16.2 dB, respectively. The mean ABG closure was 9.5 dB (range, -1.3∼35.8 dB). Seven cases obtained the best results (mean ABG closure ≤10 dB). In the remaining patient, the mean ABG closure was 9.5 dB until 6 months after surgery, but was 35.8 dB 1 year after surgery. CONCLUSIONS: IFA seems to be a reasonable surgical option in patients with missing the stapes superstructure, but with a mobile footplate in which the long process of incus is preserved. LEVEL OF EVIDENCE: 4 Laryngoscope, 126:2569-2573, 2016.

Transmastoid reshaping of the sigmoid sinus: preliminary study of a novel surgical method to quiet pulsatile tinnitus of an unrecognized vascular origin.

OBJECTIVE A dominant sigmoid sinus with focal dehiscence or thinning (DSSD/T) of the overlying bony wall is a commonly encountered, but frequently overlooked, cause of vascular pulsatile tinnitus (VPT). Also, the pathophysiological mechanism of sound perception in patients with VPT remains poorly understood. In the present study, a novel surgical method, termed transmastoid SS-reshaping surgery, was introduced to ameliorate VPT in patients with DSSD/T. The authors reviewed a case series, analyzed the surgical outcomes, and suggested the pathophysiological mechanism of sound perception. The theoretical background underlying VPT improvement after transmastoid SS-reshaping surgery was also explored. METHODS Eight patients with VPT that was considered attributable to DSSD/T underwent transmastoid SS-reshaping surgery between February 2010 and February 2015. The mean postoperative follow-up period was 9.5 months (range 4-13 months). Transmastoid SS-reshaping surgery featured simple mastoidectomy, partial compression of the SS using harvested cortical bone chips, and reinforcement of the bony SS wall with bone cement. Perioperative medical records, imaging results, and audiological findings were comprehensively reviewed. RESULTS In 7 of the 8 patients (87.5%), the VPT abated immediately after surgery. Statistically significant improvements in tinnitus loudness and distress were evident on numeric rating scales. Three patients with preoperative ipsilesional low-frequency hearing loss exhibited postoperative improvements in their low-frequency hearing thresholds. No major postoperative complications were encountered except in the first subject, who experienced increased intracranial pressure postoperatively. This subsided after a revision operation for partial decompression of the SS. CONCLUSIONS Transmastoid SS-reshaping surgery may be a good surgical option in patients with DSSD/T, a previously unrecognized cause of VPT. Redistribution of severely asymmetrical blood flow, reinforcement of the bony SS wall with bone cement to reconstruct a soundproof barrier, and disconnection of a problematic sound conduction route via simple mastoidectomy silence VPT.

Clinical observations and molecular variables of patients with hearing loss and incomplete partition type III.

OBJECTIVES/HYPOTHESIS: To analyze the clinical manifestations and genetic features of patients with hearing loss (HL) and incomplete partition (IP) type III malformation, and to evaluate speech performance after cochlear implantation (CI) in these patients. STUDY DESIGN: Individual retrospective cohort study. METHODS: Of 206 probands with inner ear malformations (IEMs), we constructed a homogeneous cohort of 11 genetically documented IP type III (DFNX2). Mutations affecting POU3F4 were classified as extension (n = 2), truncation (n = 3), large genomic deletion (n = 2), or missense substitution (n = 4). Postoperative outcomes were rigorously assessed with focus on POU3F4 genotypes and compared with 80 age-matched implantees without IEMs. RESULTS: HL in our cohort was prelingual in onset irrespective of degree. Serviceable hearing was obtained by wearing conventional hearing aids in three, and eight subjects required CI. No correlation was found between mutation types and initial auditory phenotype. As for the eight cochlear implantees, average Categories of Auditory Perception score was <1 preoperatively and 3.9 at 2 years post-CI. Speech performances improved over the first 3 months postoperatively in a manner comparable to implantees without IEMs. However, it then tended to slow down until 1 year postoperatively, leading to worse scores at 2 years than implantees without IEMs. Furthermore, this was more evident in those with a truncation or deletion mutation. CONCLUSIONS: CI surgeons should be aware that postoperative auditory performance may be not as good in IP type III patients as in patients without IEMs. In particular, our study implies that certain types of POU3F4 mutations may have poorer prognoses than other types after CI. LEVEL OF EVIDENCE: 4. Laryngoscope, 126:E123-E128, 2016.

Preoperative differences of cerebral metabolism relate to the outcome of cochlear implants in congenitally deaf children.

In congenitally deaf children, chronological age is generally accepted as a critical factor that affects successful rehabilitation following cochlear implantation (CI). However, a wide variance among patients is known to exist regardless of the age at CI [Sarant, J.Z., Blamey, P.J., Dowell, R.C., Clark, G.M., Gibson, W.P., 2001. Variation in speech perception scores among children with cochlear implants. Ear Hear. 22, 18-28]. In a previous study, we reported that prelingually deaf children in the age range 5-7 years at implantation showed greatest outcome variability [Oh S.H., Kim C.S., Kang E.J., Lee D.S., Lee H.J., Chang S.O., Ahn S.H., Hwang C.H., Park H.J., Koo J.W., 2003. Speech perception after cochlear implantation over a 4-year time period. Acta Otolaryngol. 123, 148-153]. Eleven children who underwent CI between the age of 5 and 7 1/2 years were subdivided into a good (above 65%: GOOD) and a poor (below 45%: POOR) group based on the performance in a speech perception test given 2 years after CI. The preoperative (18)F-FDG-PET (F-18 fluorodeoxyglucose positron emission tomography) images were compared between the two groups in order to examine if regional glucose metabolic difference preexisted before the CI surgery. In the GOOD group, metabolic activity was greater in diverse fronto-parietal regions compared to the POOR group. In the POOR group, the regions related to the ventral visual pathway showed greater metabolic activity relative to the GOOD group. These findings suggest that the deaf children who had developed greater executive and visuospatial functions subserved by the prefrontal and parietal cortices might be successful in auditory language learning after CI. On the contrary, greater dependency on the visual function subserved by the occipito-temporal region due to auditory deprivation may interfere with acquisition of auditory language after CI.

Head position dependency of induced nystagmus to ice-water irrigation in peripheral vestibulopathy.

OBJECTIVE: Evaluation of head-position dependency during the ice-water test is essential when the test is indicated. Because ice-water irrigation (IWI) in the prone position is frequently skipped in many laboratories, we investigated the importance of evaluating position dependency in an ice-water test. DESIGN AND SETTING: Twenty-five unilateral peripheral vestibulopathy patients showing no nystagmus during warm irrigation were included. IWI was performed in supine and prone positions, and maximum slow-phase velocity and direction of nystagmus were assessed by using video nystagmography. RESULTS: Eleven cases showed head-position dependency and were interpreted as hypofunctional. Fourteen cases showed no dependency, suggesting the absence of end organ function. In the latter group, 6 patients showing definite nystagmus in supine position could have been misinterpreted as hypofunctional, had it not been for prone-position results. CONCLUSIONS: Evaluation of head position dependency by using IWI is important in the determination of lateral semicircular canal function.

Diagnosis of major salivary gland tuberculosis: experience of eight cases and review of the literature.

CONCLUSIONS: Tuberculosis of the salivary gland is mostly a medically curable disease entity but early diagnosis is very important to ensure complete remission. In cases with a high index of suspicion, reliable diagnostic methods such as polymerase chain reaction (PCR) should always be considered before surgical intervention to enable differential diagnosis of a salivary gland tumor. OBJECTIVES: To investigate the clinical characteristics of major salivary gland tuberculosis and to review the literature relating to its diagnosis. MATERIAL AND METHODS: Eight patients diagnosed as having major salivary gland tuberculosis between 1994 and 2004 were treated at one of three tertiary referral centers. Medical records, including imaging findings and the results of microbiological tests, Mycobacterium tuberculosis PCR and histopathology, were retrospectively retrieved and the literature was reviewed. RESULTS: The parotid and submandibular glands were involved in 5 (62.5%) and 3 cases (37.5%), respectively. Neck CT demonstrated typical findings of salivary gland tuberculosis in 3 patients (37.5%). Fine-needle aspiration cytology revealed chronic inflammation in 6/7 patients (85.7%), 2 of whom (33.3%) showed caseous necrosis, strongly suggesting tuberculosis. Five of the 8 patients (62.5%) required resection of the affected gland and 3 (37.5%) received open biopsy. PCR was performed in half of the cases and was affirmative in every case. No significant differences were found between the surgically resected and non-resected groups in terms of treatment results or morbidity. All patients received anti-tuberculous chemotherapy for 8-12 months, with no disease recurrence.

De novo large genomic deletions involving POU3F4 in incomplete partition type III inner ear anomaly in East Asian populations and implications for genetic counseling.

OBJECTIVE: The aim of this study was to understand the prevalence and molecular genetic etiology of incomplete partition type III (IP type III) anomaly in Koreans. We also attempted to verify the prevalence of genomic deletions in the DFNX2 locus and to look for association between inheritance patterns and mutation type in East Asian IP type III subjects. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: Subjects with IP type III anomaly and their biological mothers. INTERVENTIONS: Sanger sequencing, array-comparative genomic hybridization (aCGH), and PCR were performed. We also analyzed the type and inheritance of the causative genetic abnormality in East Asian DFNX2 patients. MAIN OUTCOME MEASURE: Mutation type and occurrence. RESULTS: We identified IP type III in 10 (4.8%) of 206 patients with an inner ear abnormality. We confirmed an etiologic homogeneity, DFNX2, of the IP type III in this Korean population. Two (20%) of the 10 DFNX2 carried a large genomic deletion affecting POU3F4, as proved by aCGH. PCR confirmed that the 2 deletions occurred de novo. Genetic alteration occurred de novo in 29.4% (5/17) of all reported Korean IP type III cases. From this study and literature review, we observed a striking difference of de novo occurrence rate (75% versus 12.5%, p = 0.032) between large genomic deletions and point mutations in East Asian population. CONCLUSIONS: Our data suggest that different POU3F4 mutations might show different recurrence rate in siblings of the IP type III families, especially in East Asian population. Genetic counseling should be provided accordingly.

PET evidence of neuroplasticity in adult auditory cortex of postlingual deafness.

UNLABELLED: Controversy regarding functional reorganization in the adult brain remains. To investigate whether neuroplasticity is present in adults with postlingual deafness, we examined the pattern of cerebral glucose metabolism on (18)F-FDG brain PET images of postlingually deaf patients by comparing the auditory cortical activation pattern with those of age- and sex-matched healthy control subjects. We also correlated the cerebral glucose metabolism in deaf patients with the duration of deafness using statistical parametric mapping. METHODS: In the resting state (eye closed, ears unoccluded in a dark and quiet environment), (18)F-FDG brain PET scans were performed on 9 postlingually deaf patients and 9 age- and sex-matched healthy volunteers. Significant increases and decreases of regional cerebral metabolism in the patient group were estimated by comparing their PET images with those of the healthy volunteers using t statistics at every voxel. To reveal regions in which metabolism was significantly correlated with the duration of deafness, the general linear model with the duration of deafness as a covariate was tested at each voxel. RESULTS: When we compared (18)F-FDG brain PET images of postlingually deaf patients with those of age- and sex-matched healthy control subjects by performing a t test at every voxel, the glucose metabolism of deaf patients was significantly (P < 0.001) lower than that of the control subjects in both anterior cingulate gyri (Brodmann area 24 [BA24]) and superior temporal cortices (BA41, BA42) and in the right parahippocampal gyrus. No area showed a significant increase of metabolism in deaf patients with the same threshold. When we correlated glucose metabolism of deaf patients with the duration of deafness after total deprivation of hearing capability using a general linear model with the duration of deafness as a covariate at every voxel, metabolism in both anterior cingulate gyri (BA24) and superior temporal cortices (BA41, BA42) showed a significant (P < 0.005) positive correlation with the duration of deafness. CONCLUSION: This study suggests that plasticity is present in adult brains of postlingually deaf patients. In the mature brain, auditory deprivation decreased neuronal activity transiently in primary auditory and auditory-related cortices, and, over time, functional reorganization likely takes place in the auditory cortex. Plasticity was prominent in superior temporal and anterior cingulate gyri in the sensory-deprived mature brain and militated against postimplantation improvement in patients with cochlear implants.