Further audiovestibular characterization of DFNB77, caused by deleterious variants in LOXHD1, and investigation into the involvement of Fuchs corneal dystrophy.

This study focuses on further characterization of the audiovestibular phenotype and on genotype-phenotype correlations of DFNB77, an autosomal recessive type of hearing impairment (HI). DFNB77 is associated with disease-causing variants in LOXHD1, and is genetically and phenotypically highly heterogeneous. Heterozygous deleterious missense variants in LOXHD1 have been associated with late-onset Fuchs corneal dystrophy (FCD). However, up to now screening for FCD of heterozygous carriers in DFNB77 families has not been reported. This study describes the genotype and audiovestibular phenotype of 9 families with DFNB77. In addition, carriers within the families were screened for FCD. Fifteen pathogenic missense and truncating variants were identified, of which 12 were novel. The hearing phenotype showed high inter- and intrafamilial variation in severity and progression. There was no evidence for involvement of the vestibular system. None of the carriers showed (pre-clinical) symptoms of FCD. Our findings expand the genotypic and phenotypic spectrum of DFNB77, but a clear correlation between the type or location of the variant and the severity or progression of HI could not be established. We hypothesize that environmental factors or genetic modifiers are responsible for phenotypic differences. No association was found between heterozygous LOXHD1 variants and the occurrence of FCD in carriers.

The penetrance of paraganglioma and pheochromocytoma in SDHB germline mutation carriers.

Germline mutations in succinate dehydrogenase B (SDHB) predispose to hereditary paraganglioma (PGL) syndrome type 4. The risk of developing PGL or pheochromocytoma (PHEO) in SDHB mutation carriers is subject of recent debate. In the present nationwide cohort study of SDHB mutation carriers identified by the clinical genetics centers of the Netherlands, we have calculated the penetrance of SDHB associated tumors using a novel maximum likelihood estimator. This estimator addresses ascertainment bias and missing data on pedigree size and structure. A total of 195 SDHB mutation carriers were included, carrying 27 different SDHB mutations. The 2 most prevalent SDHB mutations were Dutch founder mutations: a deletion in exon 3 (31% of mutation carriers) and the c.423+1G>A mutation (24% of mutation carriers). One hundred and twelve carriers (57%) displayed no physical, radiological or biochemical evidence of PGL or PHEO. Fifty-four patients had a head and neck PGL (28%), 4 patients had a PHEO (2%), 26 patients an extra-adrenal PGL (13%). The overall penetrance of SDHB mutations is estimated to be 21% at age 50 and 42% at age 70 when adequately corrected for ascertainment. These estimates are lower than previously reported penetrance estimates of SDHB-linked cohorts. Similar disease risks are found for different SDHB germline mutations as well as for male and female SDHB mutation carriers.

Diagnostic accuracy of high-resolution T2-weighted MRI vs contrast-enhanced T1-weighted MRI to screen for cerebellopontine angle lesions in symptomatic patients.

OBJECTIVE: To evaluate diagnostic accuracy of high-resolution T2-weighted MRI (T2w) for detecting cerebellopontine angle (CPA) lesions compared to a combined protocol including gadolinium enhanced T1-weighted MRI (GdT1w). SETTING: Department of Radiology & Nuclear Medicine, Radboud University Medical Centre, Nijmegen, The Netherlands. PARTICIPANTS: A random sample of MRIs from 350 patients (700 CPAs) with asymmetrical audiovestibular complaints was used, acquired between 2013 and 2016. MAIN OUTCOME MEASURES: Sensitivity, specificity, positive and negative predictive values of T2w results compared to GdT1w and, in patients with any suggestion of CPA pathology, to the complete examination (T1w, GdT1w and T2w). Inter-rater agreement between an experienced neuroradiologist and a less experienced observer was calculated. RESULTS: Results of 678 CPAs in 340 patients were analysed. On T2w, the neuroradiologist identified all 27 lesions >2 mm in size out of a total of 30 CPA lesions (sensitivity: 90% [95% CI: 73.5%-97.9%]). Negative predictive value reached 99.5% (95% CI: 98.7-99.9). One missed lesion of 2 mm would have been detected in clinical practice, as this was one of 14 patients for which additional GdT1w would have been ordered based on T2w alone, increasing sensitivity to 93% (95% CI: 77.9%-99.2%) and negative predictive value to 99.7% (95% CI: 98.9%-100%). Inter-rater agreement for T2w was 98% (95% CI: 96.4-98.8). CONCLUSION: T2w has a very high diagnostic accuracy for the presence of CPA lesions in patients with asymmetrical audiovestibular complaints. However, in a screening protocol with T2w only, smallest vestibular schwannomas as well as rare differential diagnoses that probably only would be detected on GdT1w may remain unnoticed.

A meta-analysis on the surgical management of paraganglioma of the carotid body per Shamblin class.

OBJECTIVE: The aim of this study was to evaluate the risk associated with different types of surgery for carotid body paraganglioma of different Shamblin class. A meta-analysis was conducted to evaluate per tumour class, the local control, cranial nerve damage and complication rates of different techniques using internal carotid artery (ICA) and external carotid artery (ECA) ligation, clamping or bypassing, as well as the craniocaudal vs caudocranial techniques. DESIGN: A meta-analysis is conducted after a systematic search in PubMed and the Cochrane library, in accordance with the PRISMA guidelines. MAIN OUTCOME MEASURES: Local control, cranial nerve damage, complications, function recovery. RESULTS: Out of 3565 articles, 27 were selected. The overall quality of evidence of studies was low. Cranial nerve damage (3%, 17% and 39%) and complication rates (0%, 1% and 10%) were significantly related to Shamblin class (class 1, 2 and 3, respectively, P < .01). For class 3 tumours, an increased risk of complications was found associated with routine ICA manipulation/reconstruction (RR 3.12 with a 95% CI of 1.29-7.59), as well as a trend towards enhanced risk of routine ECA ligation (RR 3.48 with a 95% CI of 0.88-13.81). CONCLUSIONS: For class 1 and 2 tumours, surgery seems a viable treatment option. For class 3 tumours, morbidity in terms of cranial nerve deficit and complications is considerable; particularly, the use of ICA manipulation/reconstruction and potentially ECA ligation seem to be accompanied by high stroke incidence.

Psychological impact of a genetic diagnosis on hearing impairment-An exploratory study.

OBJECTIVE: Genetic testing for hereditary hearing impairment has become more routinely available as a diagnostic tool in the outpatient clinic. However, little is known about the psychological impact of a genetic diagnosis. To evaluate this impact, an exploratory study was conducted. DESIGN: Prospectively, 48 individuals who underwent genetic testing for hereditary hearing impairment were included in this study. Study participants were asked to fill out the following questionnaires: Hospital Anxiety Depression Scale, Impact of Event Scale, Self-Efficacy 24, Illness Cognition Questionnaire and the Inventory for Social Reliance. Questionnaires were filled out on three occasions: before genetic testing, directly after counselling on either positive or negative test results, and six weeks thereafter. RESULTS: No significant differences were found between the group that received a genetic diagnosis for their hearing impairment and the group that did not. CONCLUSION: This study did not demonstrate differences between receiving a genetic diagnosis or not; however, special attention to psychological well-being should be offered to hearing-impaired patients who seek a genetic diagnosis for their hearing impairment. Additionally, the psychological impact of sensorineural hearing impairment might be greater than the impact of a genetic diagnosis itself. Based on the current exploratory study, there are no psychological reasons in favour of or against genetic testing for hereditary hearing impairment.

Results of a systematic literature review of treatment modalities for jugulotympanic paraganglioma, stratified per Fisch class.

OBJECTIVE: Key for successful jugulotympanic paraganglioma management is a personalised approach aiming for the best practice for each individual patient. To this end, a systematic review is performed, evaluating the local control and complication rates for the different treatment modalities stratified by the broadly accepted Fisch classification. DESIGN: A systematic literature review according to the PRISMA statement was performed. A detailed overview of individual treatment outcomes per Fisch class is provided. MAIN OUTCOME MEASURES: Local control, cranial nerve damage, complications, function recovery. RESULTS: Eighteen studies were selected, resembling 83 patients treated with radiotherapy and 299 with surgery. Excellent local control was found post-surgery for class A and B tumours, and risk of cranial nerve damage was <1%. For class C1-4 tumours, local control was 80%-95% post-surgery (84% post-radiotherapy), and cranial nerve damage was found in 71%-76% (none post-radiotherapy; P < .05). There was no difference in treatment outcomes between tumours of different C class. For class C1-4De/Di tumours, local control was 38%-86% (98% post-radiotherapy; P < .05) and cranial nerve damage/complication rates were 67%-100% (3% post-radiotherapy; P < .05). C1-4DeDi tumours showed lesser local control and cranial nerve damage rates when compared to C1-4De tumours. CONCLUSIONS: An individual risk is constituted for surgery and radiotherapy, stratified per Fisch class. For class A and B tumours, surgery is a suitable treatment option. For class C and D tumours, radiotherapy results in lower complication rates and similar or better local control rates when compared to the surgical group.

Hearing aid fitting for visual and hearing impaired patients with Usher syndrome type IIa.

OBJECTIVES: Usher syndrome is the leading cause of hereditary deaf-blindness. Most patients with Usher syndrome type IIa start using hearing aids from a young age. A serious complaint refers to interference between sound localisation abilities and adaptive sound processing (compression), as present in today's hearing aids. The aim of this study was to investigate the effect of advanced signal processing on binaural hearing, including sound localisation. DESIGN AND PARTICIPANTS: In this prospective study, patients were fitted with hearing aids with a nonlinear (compression) and linear amplification programs. Data logging was used to objectively evaluate the use of either program. Performance was evaluated with a speech-in-noise test, a sound localisation test and two questionnaires focussing on self-reported benefit. RESULTS: Data logging confirmed that the reported use of hearing aids was high. The linear program was used significantly more often (average use: 77%) than the nonlinear program (average use: 17%). The results for speech intelligibility in noise and sound localisation did not show a significant difference between type of amplification. However, the self-reported outcomes showed higher scores on 'ease of communication' and overall benefit, and significant lower scores on disability for the new hearing aids when compared to their previous hearing aids with compression amplification. CONCLUSIONS: Patients with Usher syndrome type IIa prefer a linear amplification over nonlinear amplification when fitted with novel hearing aids. Apart from a significantly higher logged use, no difference in speech in noise and sound localisation was observed between linear and nonlinear amplification with the currently used tests. Further research is needed to evaluate the reasons behind the preference for the linear settings.

Features of autosomal recessive non-syndromic hearing impairment: a review to serve as a reference.

OBJECTIVE: Non-syndromic sensorineural hearing impairment is inherited in an autosomal recessive fashion in 75-85% of cases. To date, 61 genes with this type of inheritance have been identified as related to hearing impairment, and the genetic heterogeneity is accompanied by a large variety of clinical characteristics. Adequate counselling on a patient's hearing prognosis and rehabilitation is part of the diagnosis on the genetic cause of hearing impairment and, in addition, is important for the psychological well-being of the patient. TYPE OF REVIEW: Traditional literature review. DATA SOURCE: All articles describing clinical characteristics of the audiovestibular phenotypes of identified genes and related loci have been reviewed. CONCLUSION: This review aims to serve as a summary and a reference for counselling purposes when a causative gene has been identified in a patient with a non-syndromic autosomal recessively inherited sensorineural hearing impairment.

Patients with Pendred syndrome: is cochlear implantation beneficial?

OBJECTIVE: To evaluate the benefit of cochlear implantation in patients with Pendred syndrome. DESIGN: Retrospective study. SETTING: Tertiary centre. PARTICIPANTS AND MAIN OUTCOME MEASURES: Speech perception was measured using a phonetically balanced word list at a sound pressure level of 65 dB. Post-operative phoneme scores at 12-month for adults and 36-month for children with Pendred syndrome were compared to scores of patients with an enlarged vestibular aqueduct (EVA) and a reference group with an unknown cause of hearing impairment. Quality of life was measured with the Nijmegen Cochlear Implant Questionnaire to evaluate the differences between pre- and post-implantation. RESULTS: The mean post-operative phoneme scores were as follows: in the Pendred group, 91% (n = 16; SD = 10) for children and 78% (n = 7; SD = 14) for adults; in the reference group, 79% (n = 59; SD = 20) for children and 73% (n = 193; SD = 18) for adults; and in the EVA group, 84% (n = 6; SD = 7) for children and 66% (n = 12; SD = 22) for adults. A significant difference in speech perception was found between the children of the Pendred group and the reference group of 11.4% (SE = 5.2; P = 0.031). Between the adults, a difference of 11.2% (SE = 6.7; P = 0.094) was found. The difference between the Pendred group and the EVA group was 5.7%(SE = 4.5; P = 0.22) for children and 9.9% (SE = 8.7; P = 0.28) for adults. A significant improvement post-implantation in four of the six subdomains of the quality of life questionnaire was found: basic sound perception (P = 0.002), advanced sound perception (P = 0.004), speech production (P = 0.018) and activity limitations (P = 0.018). The two not significant subdomains were self-esteem (P = 0.164) and social interaction (P = 0.107). CONCLUSIONS: After cochlear implantation, children with Pendred syndrome performed better than the reference group with respect to speech perception, however, adults performed similar. No significant differences were found between the Pendred and EVA group. Consequently, during pre-operative counselling, the two groups of patients may be considered comparable in terms of expected speech perception performance after cochlear implantation.

Genotype phenotype correlations for hearing impairment: approaches to management.

Hearing impairment is an extremely heterogeneous disorder, with both environmental as well as genetic causes. This review describes the known genes involved in non-syndromic hearing impairment and their genotype-phenotype correlations where possible. Furthermore, some of the more frequent syndromic forms of hearing impairment are described, in particular where they overlap with the non-syndromic forms. Given the heterogeneity of the disorder, together with the indistinguishable phenotypes for many of the genes, it is suggested that testing for mutations is performed using massive parallel sequencing techniques, either by a large targeted set of genes or by an exome wide analysis.