Three-dimensional quantification of fibrosis and ossification after cochlear implantation via virtual re-sectioning: Potential implications for residual hearing.

Hearing preservation may be achieved initially in the majority of patients after cochlear implantation, however, a significant proportion of these patients experience delayed hearing loss months or years later. A prior histological report in a case of delayed hearing loss suggested a potential cochlear mechanical origin of this hearing loss due to tissue fibrosis, and older case series highlight the frequent findings of post-implantation fibrosis and neoosteogenesis though without a focus on the impact on residual hearing. Here we present the largest series (N = 20) of 3-dimensionally reconstructed cochleae based on digitally scanned histologic sections from patients who were implanted during their lifetime. All patients were implanted with multichannel electrodes via a cochleostomy or an extended round window insertion. A quantified analysis of intracochlear tissue formation was carried out via virtual re-sectioning orthogonal to the cochlear spiral. Intracochlear tissue formation was present in every case. On average 33% (SD 14%) of the total cochlear volume was occupied by new tissue formation, consisting of 26% (SD 12%) fibrous and 7% (SD 6%) bony tissue. The round window was completely covered by fibro-osseous tissue in 85% of cases and was associated with an obstruction of the cochlear aqueduct in 100%. The basal part of the basilar membrane was at least partially abutted by the electrode or new tissue formation in every case, while the apical region, corresponding with a characteristic frequency of < 500 Hz, appeared normal in 89%. This quantitative analysis shows that after cochlear implantation via extended round window or cochleostomy, intracochlear fibrosis and neoossification are present in all cases at anatomical locations that could impact normal inner ear mechanics.

Speech-in-noise testing as a marker for noise-induced hearing loss and tinnitus.

Speech-in-noise testing as a marker for noise-induced hearing loss and tinnitus. Noise-induced hearing loss and tinnitus are auditory complaints that often co-occur. Often, there is no immediate indication of changes in the pure tone audiogram. Patients can still have clinically normal hearing thresholds while clearly experiencing reduced speech comprehension. This might be explained by the process of neurodegeneration of the innervated dendrites of the auditory nerve fibres and secondary degeneration of spiral ganglion neurons. Subsequent maladaptive neuronal plasticity of the central auditory system can induce tinnitus. Standard hearing testing is no longer sufficient in these patients. Therefore more complex tasks, such as speech-in-noise tests, might be valuable extensions to the standard hearing tests. We carried out a prospective investigation of the influence of tinnitus upon speech comprehension in noise and the effectiveness of speech-in-noise testing, using the Flemish version of the digit triplet test (DTT). Thirty-seven patients with mild noise-induced hearing loss, tinnitus complaints and clinically normal pure tone thresholds completed the DTT and filled in two tinnitus enquiries. A statistically significant (p=0.026) correlation between the averaged high PTA, 2,z and the averaged SRT across ears on the DTT was found. There also seems to be a slight influence of tinnitus onset on the SRT score.

Predictive factors of speech understanding in adults with cochlear implants.

OBJECTIVE: The aim of this study was to analyse the factors that influenced speech recognition scores in quiet conditions and speech reception threshold levels (SRT) in fixed noise conditions, after cochlear implant (CI) surgery in adults with postlinguistic deafness. STUDY DESIGN: Combined retrospective and prospective study in a tertiary referral centre. METHODS: We included 66 patients that received implants between 2002 and 2013. We retrospectively collected speech recognition scores and 14 demographic, audiological, and technical factors, including gender, age at implantation, aetiology, hearing loss progression, preoperative Pure Tone Average (PTA), hearing loss onset age and duration, duration and use of hearing aids (HAs); implantation in the best or worst ear; implantation on the right or left side; use of HA after implantation; and the duration and type of CI. We prospectively tested a subgroup of 21 patients for SRT in fixed noise. RESULTS: The hearing loss duration significantly affected speech recognition scores in quiet conditions (H (4) = 10.567, p =0.032) and SRTs in fixed noise conditions (rs = 0.466, p = 0.033). The PTA of the better ear significantly affected only the SRT in fixed noise conditions (rs = 0.57 1, p = 0.007). CONCLUSION: The duration of hearing loss and the PTA of the best ear had significant effects on the outcomes of speech recognition and SRT in quiet and fixed noise conditions, respectively. These findings are important for counselling CI candidates. Further studies in larger study populations are warranted.

Otosclerosis: Shift in bone conduction after stapedotomy.

OBJECTIVES: To analyze changes in bone conduction (BC) thresholds before and after stapedotomy in patients with clinical otosclerosis with a focus on the Carhart notch, which is defined as a significant loss of BC at a certain audiometric frequency. METHODOLOGY: Retrospective case review of pure tone audiometry (PTA) in 213 patients who underwent a stapedotomy at a tertiary referral center between 2004 and 2011. The patients were grouped by age and the frequency of the Carhart notch. The non-operated ear was also evaluated. RESULTS: The Carhart notch was present on pre-operative audiometry in 158 (74%) patients at 0.5 (n = 18, 8.45%), 1 (n = 25, 11.70%), or 2 kHz (n = 115, 54.0%). We measured a mean postoperative improvement in BC of 7.5, 8.4, and 8.8 dB HL. Pre-operatively, 55 (25.8%) patients did not exhibit a typical notch configuration. The mean gain in BC, defined on PTA according to the AAO-HNS criteria (0.5, 1, 2 and 3, or 4 kHz), was 1.8 dB HL after stapedotomy. CONCLUSION: The Carhart notch was not solely related to the 2 kHz frequency. The greatest gain in BC after stapedotomy for otosclerosis occurred at the notch frequency.

Aetiology of congenital hearing loss: a cohort review of 569 subjects.

OBJECTIVE: Newborn hearing screening was implemented in Flanders about fifteen years ago. The aim of this study was to determine the aetiology of hearing loss detected by the Flemish screening programme. METHODS: From 1997 to 2011, 569 neonates were referred to our tertiary referral centre after failed neonatal screening with Auditory Brainstem Responses. In case hearing loss (HL) was confirmed, further diagnostic testing was launched. A retrospective chart review was performed analysing the degree of HL, risk factor and aetiology. RESULTS: Metabolic disorders (0.5%), infectious diseases (35.8%), congenital malformations (6.1%) and genetic abnormalities (19.8%), whether or not syndromic, were retained. In 35% of the subjects no obvious aetiology could be determined in the current study. CONCLUSION: In contrast to the literature findings, this series shows a genetic syndromic cause in 80% of the genetic bilateral HL cases. On the other hand connexin positive diagnoses were mostly underrepresented in this study, showing the need for better screening.

Noise exposure of care providers during otosurgical procedures.

OBJECTIVE: To monitor the noise exposure of care providers during otological surgery due to drilling and suction in the operating room. METHODS: A clinical study monitoring different standard otosurgical procedures was conducted; cochlear implantation (CI), mastotympanoplasty, and mastoidectomy alone. Noise exposure to the surgeon and assistant were monitored with wireless personal noise dosimetry and stationary sound monitoring. Both maximum peak level in dBC (Lpeak) and time-average sound pressure level in dBA (equivalent level or Leq) were measured during drilling episodes. Frequency analysis in one third octaves covering the frequency bands 6.3 Hz to 20 k Hz was performed using a sound analyzing program. RESULTS: When averaged over the entire procedure, the sound pressure level was highest for the surgeon and the assistant with values of 76.0 dBA and 72.5 dBA, respectively, during CI. Lpeak was 135.9 dBC. Leq for the stationary sound measurement was 74.2 dBA. During cortical bone work using a cutting burr, 84.6 dBA was measured. Mean values of L95% (estimation of the background noise) were between 55.8 dBA and 61.2 dBA. Frequency analysis showed the highest sound pressure level for all procedures was between 2.5 kHz and 3.15 kHz. CONCLUSION: This is the first study to use personal sound dosimetry to monitor noise exposure during otosurgical drilling. In accordance with other studies, the results presented show sound levels below international occupational noise level regulations. However, the measured noise exposure during drilling could have negative effects on care providers based on unfavorable acoustical comfort.

Syndromic disorders in congenital hearing loss.

OBJECTIVES: To investigate the aetiology of congenital hearing loss detected by the universal neonatal hearing screening programme (Algo) that was introduced in Flanders 15 years ago, and, more specifically, to investigate genetic causes. METHODOLOGY: Diagnostic work-up of all children with confirmed hearing loss after referral by the Algo screening programme and screening at the neonatal intensive care unit (NICU) of our university hospital. RESULTS: A hearing loss was confirmed in 505 of the 569 neonates (18% from NICU) referred between 1997 and 2011. After further examination, a genetic origin was identified in 84 (17%) of 100 children with a syndromic hearing loss. The most frequent syndromes are discussed. CONCLUSION: A higher percentage of syndromic hearing loss was found than in the literature. This could be explained by the good cooperation with the human genetics department and the proportion of children retrieved from the neonatal intensive care unit.

Long-term audiological follow-up of children with congenital cytomegalovirus.

OBJECTIVE: To evaluate the audiological outcome of children with congenital cytomegalovirus infection. METHODOLOGY: In a prospective study, the hearing of 98 congenitally cytomegalovirus-infected children born between January 2003 and July 2009 was systematically evaluated until the age of six using the Flemish CMV protocol. Symptomatic children with hearing loss at birth were treated with ganciclovir, if parents consented. RESULTS: Seventy children passed initial screening, 28 had unilateral or bilateral hearing loss. In the normal hearing group, one asymptomatic and two symptomatic children developed late-onset hearing loss. Eight children in the group with hearing loss at birth received ganciclovir. Nine symptomatic and 11 asymptomatic children did not receive ganciclovir. In the treated group, 37.5% of the children had stable hearing loss, and 37.5% had progressive and/or fluctuating hearing loss. First progression or fluctuation always occurred after the age of one year. The hearing threshold improved in 25.0%. The improvement took place during or shortly after treatment. Hearing loss remained stable in 33.3% of the untreated symptomatic children, while progression or fluctuation occurred in 55.5%. In the asymptomatic group, hearing loss was most commonly stable (63.6%). The first change in the hearing threshold was almost always detected before the age of one year in both untreated groups. CONCLUSIONS: Hearing loss caused by congenital cytomegalovirus infection cannot be defined unequivocally either with respect to the level of hearing loss or its evolution over time. Treating symptomatic children with ganciclovir leads to a better prognosis during the first year of life, after which progression or fluctuation again becomes more likely. However, overall, progression is more common in the untreated symptomatic group. Asymptomatic children with SNHL are more likely to have a stable hearing status.

Fifteen years of early hearing screening in Flanders: impact on language and education.

OBJECTIVES: To assess the impact of fifteen years of universal neonatal hearing screening in Flanders on language development and the educational setting. METHODOLOGY: An analysis of the database of Kind en Gezin from 1997 to 2012 and a long-term evaluation of the children referred to our centre after failed neonatal hearing screening. The CELF and PPVT language tests were performed. RESULTS: Between 1997 and August 2012, bilateral hearing loss was confirmed in 2393 children in Flanders, of whom 11.4% were referred to our tertiary centre. The educational setting and language development of 84 children older than 5 years was evaluated and 54% of them had additional disabilities. Of the children without additional disabilities, 84% attended mainstream schools; 42% of children with additional disabilities entered mainstream education with additional support. There was a significant correlation between the number of additional disabilities and the education level (p < 0.001) and between the degree of hearing loss and educational placement (p < 0.001). Data on language development were available for 76% of the children and a significant correlation could be demonstrated only between the results of the PPVT language and the number of additional handicaps (p < 0.008). CONCLUSIONS: The majority of children receiving early treatment after neonatal hearing screening enter mainstream education. The number of additional disabilities has a significant effect on education level and language development.

Impact of early hearing screening and treatment on language development and education level: evaluation of 6 years of universal newborn hearing screening (ALGO) in Flanders, Belgium.

OBJECTIVES: Early intervention in hearing-impaired children may improve language outcomes and subsequent school and occupational performance. The objective of this study was to retrospectively analyze over 6 years the educational outcome and language development of a first cohort of children, detected by the Flemish universal newborn hearing screening (UNHS) program based on automated auditory brainstem response (AABR), with the oldest children being in primary school. METHODS: We studied 229 hearing-impaired children from 1998 till 2003. The following variables were considered: the age during the school year 2005-2006, the degree of hearing loss, additional impairments including presence of intellectual disability, school placement and early intervention. RESULTS: Analysis showed that 85.4% of the children with moderate, severe or profound hearing loss and no additional disability, older than 5.5 years, reach mainstream education. Further detailed description was provided for the outcomes of children with uni- and bilateral cochlear implants. Overall results stress that 46% of all children with a cochlear implant obtain mainstream education. Of all cochlear implant (CI) children above 5.5 years, without additional handicaps, 78.9% of children attend primary mainstream school. Data on language development show that up to 45% of the children with unilateral cochlear implant and no additional disabilities had normal to slight delay on language development. These data are fulfilling the goals stated by the JCIH and the American Academy of Pediatrics (AAP) in 2000. The role and impact of additional handicaps is discussed. The importance of early hearing loss identification and hearing therapy for appropriate language development is highlighted. Finally our preliminary results on children with bilateral cochlear implants without additional handicaps present an improved language development in comparison to unilateral CI-children. CONCLUSION: A vast majority of the children detected by the UNHS program, with moderate, severe or profound hearing loss and no additional disability, older than 5.5 years, reach mainstream education. Additional disabilities have a major influence.

Levothyroxine replacement therapy after thyroid surgery.

INTRODUCTION AND AIM: New entities, such as 'subclinical' over- and undersubstitution, are easily diagnosed after thyroid surgery due to improved testing methods, and the incidence of thyroidectomy with lifelong hormone substitution is increasing. Thus, there is a need to review conventional replacement therapy after thyroid surgery. We investigated the adequacy of our thyroid hormone replacement therapy for three months after total-, subtotal-, and hemithyroidectomy using an upper reference limit of thyrotropin (TSH) of 4.6 mU/L. MATERIALS AND METHODS: Eighty-seven patients undergoing thyroidectomy for benign thyroid pathology participated. Levothyroxine (L-T4) treatment began five days after surgery. Preoperatively euthyroid patients received 150 microg L-T4 daily following total thyroidectomy, 100 microg L-T4 after subtotal thyroidectomy, and 50 microg L-T4 after hemithyroidectomy. Preoperatively hyperthyroid patients received 100 microg L-T4 following total thyroidectomy and 50 microg L-T4 following subtotal thyroidectomy. An average of six weeks after surgery, thyrotropin (TSH) was measured (reference limits 0.15-4.60 mU/L), and necessary dose adjustments were made. RESULTS: Of the patients who were preoperatively euthyroid, 45% with total thyroidectomy, 42% with subtotal thyroidectomy, and 17% with hemithyroidectomy required L-T4 dose adjustments. Of the patients who were preoperatively hyperthyroid, 60% of those with total thyroidectomy and all of those with subtotal thyroidectomy required L-T4 dose adjustments. CONCLUSIONS: To avoid over- and undersubstitution after thyroidectomy, an optimal replacement therapy dose is necessary. A small majority of our preoperatively euthyroid patients received adequate therapy. Endocrinological follow-up six weeks after surgery revealed the need for L-T4 dose adjustments, especially in preoperatively hyperthyroid patients. When the extent of resection was similar for hyperthyroid and euthyroid patients, the same initial dose of L-T4 was justified.