Maciej Wróbel

Mutation analysis of mitochondrial 12S rRNA gene in Polish patients with non-syndromic and aminoglycoside-induced hearing loss.

Mutations in mitochondrial DNA have been reported as associated with non-syndromic and aminoglycoside-induced hearing loss. In the present study, we have performed mutational screening of entire 12S rRNA gene in 250 unrelated patients with non-syndromic and aminoglycoside-induced hearing loss. Twenty-one different homoplasmic sequence variants were identified, including eight common polymorphisms, one deafness-associated mutation m.1555 A>G and three putatively pathogenic variants: m.669 T>C, m.827 A>G, m.961 delT+C(n)ins. The incidence of m.1555 A>G was estimated for 3.6% (9/250); however, where aminoglycoside exposure was taken as a risk factor, the frequency was 5.5% (7/128). Substitution m.669 T>C was identified only in patients with hearing impairment and episode of aminoglycoside exposure, which may suggest that such additional risk factors must appear to induce clinical phenotype. Moreover, two 12S rRNA sequence variants: m.988 G>A and m.1453 A>G, localized at conserved sites and affected RNA secondary structure, may be new candidates for non-syndromic and aminoglycoside-induced hearing loss associated mutations.

Screening of the General Polish Population for Deafness-Associated Mutations in Mitochondrial 12S rRNA and tRNASer(UCN) Genes

Mutations in mitochondrial DNA are associated potentially with nonsyndromic and aminoglycoside-induced hearing loss. Several nucleotide changes associated with hearing impairment were described; however, a variable frequency of deafness-associated mutations in different populations has been observed. The aim of the present study was to determine the frequency of pathological mutations in mitochondrial 12S rRNA and tRNA(Ser(UCN)) genes in a group of 500 individuals representative of the general population of Poland. Mutational screening of 12S rRNA revealed the presence of three deafness-associated mutations, A827G, T961C, and A1555G, and one potentially pathogenic substitution, T669C. The carrier frequency of pathological mutations was estimated to be 1.2% (6/500) in the general Polish population. A deafness-associated G7444A mutation in the precursor of tRNA(Ser(UCN)) gene was identified in 8/500 (1.6%) unrelated blood donors. Seven nucleotide changes identified in 12S rRNA (G709A, G750A, G930A, T1243C, T1420C, and G1438A) and tRNA(Ser(UCN)) (C7476T), based on a frequency exceeding 1.0%, were considered as polymorphisms of 12S rRNA and tRNA(Ser(UCN)) in the studied population. Mitochondrial 12S rRNA gene seems to be the hot spot for deafness-associated mutations in the Polish population. The relatively high carrier frequency of tRNA(Ser(UCN)) G7444A (1/62) suggests that this substitution might be a nonpathogenic polymorphism in the Polish population.

Polish Universal Neonatal Hearing Screening Program-—4-year experience (2003—2006)

OBJECTIVE The aim of this paper is to share our experience and observations in running the Universal Neonatal Hearing Screening Program on a national level, present results and indicate some problems that have arisen during these 4 years. METHODS Polish Universal Neonatal Hearing Screening Program started back in 2002 in all neonatal units in Poland. Implemented testing methods consisted of test of transient evoked otoacoustic emission (TEOAE) performed in all new born children in their first 2-3 days of life and auditory brainstem response testing (ABR) conducted on children, who did not meet the TEOAE pass criteria. Additional questionnaire registered information on ototoxic drugs and family history of hearing impairment in every newborn. Diagnosed children were further referred for treatment and rehabilitation. RESULTS After 4 years of running the program (between 2003 and 2006) a total number of 1,392,427 children were screened for hearing impairment, what stands for 96.3% of all delivered babies, registered in Poland. The screening program enabled to identify and refer for further treatment 2485 children with various types of hearing loss, 312 with profound (0.02% of population) and 145 with severe sensorineural hearing loss (0.11% of population). CONCLUSIONS Our results indicate the accuracy of newborn hearing screening which remain an issue. Although improvement is needed in both intervention systems and diagnostic follow-up of hospitals, the Polish Universal Neonatal Hearing Program fully has achieved the main goal, the identification and treatment of hearing impaired children.

Toll-like receptors 2, 3 and 4 (TLR-2, TLR-3 and TLR-4) are expressed in the microenvironment of human acquired cholesteatoma

Human toll-like receptors (TLR 1-10) are crucial in the induction and activation of innate immunity in the course of an infection. They are expressed mainly on the cells of the immune system, and also on some epithelia and endothelia. Their ligands so called pathogen associated molecular patterns are abundant on invading microbes. TLR-ligand binding results in cell signal transduction and subsequent production of various proinflammatory cytokines such as IL-1 and TNF-α. Acquired cholesteatoma is formed during chronic otitis media in the proportion of cases. It has adverse effects on ear structures, resulting in osteolysis and bone resorption. Its formation and pathogenesis are not fully understood. The current study attempted to search the possible role of TLRs in this somewhat awkward pathological condition. Surgical specimens of human acquired cholesteatoma (n=15) and normal external auditory canal skin (n=5, control tissues) were tested by immunohistochemistry for the presence of TLRs. Three TLRs were examined: TLR-2, TLR-3 and TLR-4. All TLRs tested were demonstrated in matrix (layer of keratinizing epithelium) and perimatrix (granulation tissue) of this inflammatory tumour. Expression of particular TLRs within the keratinizing epithelium was distinct and uneven. In the perimatrix, numerous T (CD3+) cells were seen and relatively few macrophages (CD11c+, HLA-DR+). There was a weak expression of all TLRs on normal (non-inflammatory) skin. Expression of TLR-3 both on the epithelium and some cells within the perimatrix and the presence of T cells may suggest that apart from innate immune responses, mechanisms of adaptive immunity also operate in cholesteatoma. Weak expression of these receptors on normal skin may also suggest the important role of TLRs in the etiopathogenesis of cholesteatoma.

New insight into Baha® implant stability measurements: observations on resonance frequency analysis results.

Objective To analyze the results of multiple measurements of resonance frequency analysis (RFA) repeated in patients implanted with Cochlear Baha® BI300 implants to look for trends, which potentially might serve as indicators of successful osseointegration. Patients Forty-five patients implanted with the BI300 implants at the Department of Otolaryngology, Poznan University of Medical Sciences; consecutive values were available for 14 of these 45 patients. Intervention(s) Evaluation of the implant stability through resonance frequency analysis; 4 to 10 measurements in each patient were performed during the surgery and after 1 week and 1 month. Main Outcome Measure(s) Attention was focused on the results of RFA, defined as the differences between recorded marginal values of the implant stability quotient (ISQ): the average-ISQ value [(maximal ISQ value + minimal ISQ value)/2] and delta-ISQ (maximal ISQ value - minimal ISQ value). Results The average-ISQ value increased from 58.43 at the time of implant placement to 61.89 at the end of the observation period, with a minimum recorded value of 56 and a maximum of 64.5. Delta-ISQ showed a maximal drop from 3.86 at the time of surgery to 1.93 after 1 month. Significant differences were observed between surgery and a month later but also between 1 week and 1 month after surgery. Conclusion Our data demonstrate that differences between recorded stabilities of the implant in different planes based on ISQ values tend to decrease over time, indicating that the implant acquires symmetrical stability, which may reflect the good quality of the bone-implant interface.

Presurgical evaluation of retroauricular subcutaneous tissue thickness in BAHA surgery.

Objective A growing population of implanted patients benefit from the Bone-Anchored Hearing Aid (BAHA). An important step in the surgery is subcutaneous tissue reduction. The proper preparation of the implant site depends on relevant tissue removal, which is combined with incision, surgical technique, and preliminary retroauricular tissue thickness. Study Design Prospective analysis. Setting Authors attempt to measure the retroauricular subcutaneous tissue thickness and try to trace the correlation between retroauricular subcutaneous tissue thickness with objective parameters such as sex, height, weight, and age. Patients Group of hundred randomly selected patients were enrolled in the study. Intervention(s) Standard ultrasound with liner transducer probe was applied to measure the tissue thickness. Main Outcome Measures Sex, weight, height, and age were correlated with retroauricular tissue thickness; results also were calculated for body mass index. Results The retroauricular subcutaneous tissue thickness ranged between 2.0 and 11.0 mm with the mean value of 5.25 mm. Statistical validation revealed strong correlation with weight and body mass index. Statistical difference was found between retroauricular subcutaneous tissue thickness and sex, confirming women to have thinner subcutaneous tissue than men. The age of the patient also was predictive but without the linear correlation. Conducted measurements revealed no association between retroauricular subcutaneous tissue thickness and height of the patients enrolled in the study. Conclusion Our results provide a predictive value during preoperative counseling of patients and planning the surgery. Basic information obtained during the examination can help choose the optimal implantation technique. The ultrasound examination applied in the study turned to be an easy and reliable method to assess the retroauricular tissue thickness before the surgery.

Stent-graft treatment of extracranial internal carotid artery aneurysm

Extracranial internal carotid artery aneurysm is not a frequent finding. Although there are a number of methods used for the treatment of this kind of pathology, every approach should be tailored to the patient. The authors describe the case of a patient with a large extracranial internal carotid artery aneurysm presenting as a tumor of the parapharyngeal space, treated with a stent-graft. The patient remains asymptomatic at the 2-year follow-up. To our knowledge, this type of successful treatment of a carotid aneurysm has been reported only once so far.

Hearing impairment in Polish infants.

To the Editor: Hearing impairment has been reported as occurring in 1 to 2 per 1000 neonates.1,2 However, hearing loss is a highly heterogeneous condition, with varying severity (mild, moderate, severe, and profound) and type (conductive, sensorineural, and mixed). Hearing loss can be unilateral or bilateral, stable or progressive, and temporary or permanent. Hearing “loss” or impairment typically refers to a hearing limit of 40 dB for the better ear.1 With wider inclusion criteria for hearing impairment (a limit of 25 dB in the worse ear), the prevalence of hearing impairment in infants has been reported as 2 to 3 per 1,000.2 Profound hearing loss defined as a bilateral sensorineural hearing limit of ≥ 70 dB has been reported in 4 to 10 per 10,000.3 Thus, population levels of hearing loss are highly dependent on definition. We present a detailed description of hearing impairment in Polish children up to 1 year of age. This population is relatively homogenous with respect to ethnic background, socioeconomic conditions, and health status. Data were obtained through the Polish Universal Neonatal Hearing Screening Program, organized and run by the charity foundation Great Orchestra of Christmas Charity (www.wosp.org.pl/eng). The program started in 2002, and since January 2003 has tested all newborns in Poland,4 >3.5 million babies. On the basis of data from the Polish Central Statistical Office, we estimate that 96% of the newborn population in Poland are screened in this program. Our results are based on infants registered in the program database between 2003 and 2011 (3,322,349 babies). Of these screened children, 9% (n = 292,375) were referred for further hearing evaluation. Among these, 9872 children (2.97 per 1000 infants) were diagnosed as having a hearing problem (defined as any hearing impairment with a threshold >20 dB). However, this evaluation did not originally specify diagnosis type or severity. More thorough evaluation was initiated after the start of the program and covered 5443 of the 9872 children. Assuming that the children who received thorough screening are representative of all children with hearing impairments, we have estimated the following population prevalence. Permanent (sensorineural) bilateral hearing impairment was found in 1.38 per 1000 children (Table). Of these, 40% had severe-to-profound bilateral hearing loss (the most devastating) (0.55 per 1,000). Of the two other types of bilateral hearing impairment, conductive loss was found in 0.47 per 1,000 and mixed hearing loss in 0.24 per 1,000, with a total of 2.09 per 1,000 having bilateral hearing loss. Including those with unilateral hearing loss, serious hearing loss was present among 3.0 per 1000 children. Considering only those with hearing loss >40 dB, prevalence was 2.0 per 1000—consistent with the prevalence estimates in other populations. We infer from these results that our extrapolation from the subset of children with complete examinations was sound. The more specific categorizations by severity and type of hearing loss shown in the Table provide a level of detail not usually available on a population level.

Comparison of rehabilitation results in deaf patients with and without genetically related hearing loss

Abstract The introduction of prognostic tools to evaluate rehabilitation progress in cochlear implant patients (CI patients) is of great importance. The authors attempted to verify whether the identified 35delG mutation in the GJB2 gene can serve as a valuable indicator for rehabilitation progress of CI patients. A group of 51 subjects was studied. Molecular analysis was based on the identification of 35delG in GJB2. Logopedic assessment was performed with a non-verbal test of seven sounds, evaluating detection, discrimination and identification of the sounds during the first, third and sixth months after implantation. Results indicated that patients with GJB2-related deafness (DFNB1)s achieve better results in rehabilitation, but only at the early stages of rehabilitation. Prolonged rehabilitation equalised differences, which, subsequently, excluded this marker as an indicator for rehabilitation evaluation. Copyright

The risk factor profile of children covered by the Polish universal neonatal hearing screening program and its impact on hearing loss incidence

OBJECTIVE The high frequency of risk factors detected within the newborn population increases the total number of children that should receive regular follow-ups. However, in some circumstances, this could be beyond the capacity of the health system. Therefore, careful interpretation and selection of risk factors, and in particular of those factors not strictly defined, should be carried out during screening. The aim of the study was to analyse the risk factor profile of children covered by the national universal neonatal hearing screening program and to correlate it with hearing loss incidence. PATIENTS AND METHODS The analysis of records in the program database collected from 472 neonatal and well-baby units over a period of 10 years (2002-2012), focused on children with at least one risk factor. The analysis was subdivided into distribution of risk factors as well as to risk factors and hearing loss correlation. RESULTS In the studied cohort of n=137,432 children (4% of the total number of screened children) single risk factors were most frequently detected, accounting for 71% of records. The association of two or more risk factors appeared in 659 configurations (29%), with a mean of 3.1 coexisting risk factors and a maximum of 9. Hearing loss was dependent on the number of risk factors in a child, but reached its maximum with the association of 6 factors. CONCLUSIONS The detection of postnatal hearing loss should be continued in order to increase our understanding of hearing incidence and the role of environmental factors. To optimize screening, discussions between specialists (mostly related to the issue of risk factors detected and registered in the earliest stage of screening programs) would be beneficial.