Pathogenic mtDNA variants, in particular single large-scale mtDNA deletions, are strongly associated with post-lingual onset sensorineural hearing loss in primary mitochondrial disease.

In this retrospective cohort study of 193 consecutive subjects with primary mitochondrial disease (PMD) seen at the Children's Hospital of Philadelphia Mitochondrial Medicine Frontier Program, we assessed prevalence, severity, and time of onset of sensorineural hearing loss (SNHL) for PMD cases with different genetic etiologies. Subjects were grouped by genetic diagnosis: mitochondrial DNA (mtDNA) pathogenic variants, single large-scale mtDNA deletions (SLSMD), or nuclear DNA (nDNA) pathogenic variants. SNHL was audiometrically confirmed in 27% of PMD subjects (20% in mtDNA pathogenic variants, 58% in SLSMD and 25% in nDNA pathogenic variants). SLSMD had the highest odds ratio for SNHL. SNHL onset was post-lingual in 79% of PMD cases, interestingly including all cases with mtDNA pathogenic variants and SLSMD, which was significantly different from PMD cases caused by nDNA pathogenic variants. SNHL onset during school age was predominant in this patient population. Regular audiologic assessment is important for PMD patients, and PMD of mtDNA etiology should be considered as a differential diagnosis in pediatric patients and young adults with post-lingual SNHL onset, particularly in the setting of multi-system clinical involvement. Pathogenic mtDNA variants and SLSMD are less likely etiologies in subjects with congenital, pre-lingual onset SNHL.

Extended genetic diagnostics for children with profound sensorineural hearing loss by implementing massive parallel sequencing. Diagnostic outcome, family experience and clinical implementation.

OBJECTIVES: The aim of this study was to investigate genetic outcomes, analyze the family experience, and describe the process of implementing genetic sequencing for children with profound sensorineural hearing loss (SNHL) at a tertial audiological center in southern Sweden. DESIGN: This is a prospective pilot study including eleven children with profound bilateral SNHL who underwent cochlear implant surgery. Genetic diagnostic investigation was performed with whole exome sequencing (WES) complemented with XON-array to identify copy number variants, using a manually curated gene panel incorporating 179 genes associated with non-syndromic and syndromic SNHL. Mitochondrial DNA (mtDNA) from blood was examined separately. A patient reported experience measures (PREM) questionnaire was used to evaluate parental experience. We also describe here the process of implementing WES in an audiology department. RESULTS: Six female and five male children (mean 3.4 years, SD 3.5 years), with profound bilateral SNHL were included. Genetic variants of interest were found in six subjects (55%), where three (27%) could be classified as pathogenic or likely pathogenic. Among the six cases, one child was found to have a homozygous pathogenic variant in MYO7A and two children had homozygous likely pathogenic variants in SLC26A4 and PCDH15, respectively. One was carrying a compound heterozygote frameshift variant of uncertain significance (VUS) on one allele and in trans, a likely pathogenic deletion on the other allele in PCDH15. Two subjects had homozygous VUS in PCDH15 and ADGRV1, respectively. In five of the cases the variants were in genes associated with Usher syndrome. For one of the likely pathogenic variants, the finding was related to Pendred syndrome. No mtDNA variants related to SNHL were found. The PREM questionnaire revealed that the families had difficulty in fully understanding the results of the genetic analysis. However, the parents of all eleven (100%) subjects still recommended that other families with children with SNHL should undergo genetic testing. Specifically addressed referrals for prompt complementary clinical examination and more individualized care were possible, based on the genetic results. Close clinical collaboration between different specialists, including physicians of audiology, audiologists, clinical geneticists, ophthalmologists, pediatricians, otoneurologists, physiotherapists and hearing habilitation teams was initiated during the implementation of the new regime. For all professionals involved, a better knowledge of the diversity of the genetic background of hearing loss was achieved. CONCLUSIONS: Whole exome sequencing and XON-array using a panel of genes associated with SNHL had a high diagnostic yield, added value to the families, and provided guidance for further examinations and habilitation for the child. Great care should be taken to thoroughly inform parents about the genetic test result. Collaborations between departments were intensified and knowledge of hearing genomics was increased among the staff.

School-based hearing screening in Sweden - An evaluation of current practices.

OBJECTIVES: Routines for school hearing screening vary between municipalities in Sweden, and no study has been carried out to investigate how this is conducted throughout the country. The aim of the present study was to determine the extent of school hearing screening, and how it is performed in all the municipalities in Sweden. METHODS: An online survey was used to collect information on school hearing screening from municipalities in Sweden (N = 290). The survey included questions on the performance of hearing screening, including stimulus level and frequencies tested, the criteria for referral for further hearing evaluation, as well as the equipment and room used for testing, and who carried out the screening. Questions were also included on experience of, and attitudes towards hearing screening. RESULTS: Answers were received from 225 municipalities (response rate 78%). Universal school hearing screening was performed in 202 municipalities, while in the other municipalities hearing screening was performed when a child was evaluated due to speech delay or learning difficulties. Many different protocols were used involving different stimulus levels, frequencies, and referral criteria. The most common was testing with pure tone audiometry with a lowest stimulus level of 20 dB HL at five frequencies, 500-6000 Hz. Hearing screening was usually performed in the preparation class (6 years of age), while in other municipalities it was performed in year 1 (7 years of age). Hearing screening was usually performed once in primary school, while some municipalities carried out screening once in primary school and once in high school. More rarely, hearing screening was conducted twice in primary school. In 25 % of the municipialities, newly arrived immigrant children were screened. Difficulties in performing hearing screening were reported, such as lack of soundproof rooms, lack of time and technical difficulties. There was an opinion among the participants that identifying students with hearing loss is important, as it affects their learning ability and communication skills. and they expressed a desire for national guidelines. CONCLUSIONS: Hearing screening is performed in the vast majority of municipally run schools in Sweden. The way in which screening was performed varied regarding the stimulus level and frequencies used, as well as the criteria for referral to a specialist. The attitude towards hearing screening was positive among the participants. Hearing screening of newly immigrated children is important as their previous medical history is often unknown. There is a need for national guidelines on hearing screening of Swedish schoolchildren. Efforts must continue to ensure that the same level of healthcare regarding children's hearing is provided throughout the whole of Sweden.

Preschool hearing screening in Sweden. An evaluation of current practices and a presentation of new national guidelines.

OBJECTIVES: As the various regional authorities responsible for health care in Sweden operate independently, no knowledge was available on pre-school hearing screening available to children living in different parts of the country. The aim of this study was to carry out a survey to ascertain how preschool hearing screening was performed in the various regions of Sweden. An objective of the present paper was also to present the uniform national guidelines for pre-school hearing screening that were launched by health authorities and were based on this study. A follow-up investigation was performed to ascertain whether the new guidelines were well accepted and followed throughout the country. METHODS: A questionnaire was sent to 25 physicians responsible for child health care centers in all 21 regions throughout the whole country. The questionnaire included detailed questions on hearing screening in preschool children. New national guidelines were introduced in cooperation with health authorities and providers of preventive child health care. After two and four years, questionnaires were sent to the same recipients to determine whether changes in practice in pre-school hearing screening had been implemented, and to obtain information about experiences with the new guidelines. RESULTS: Sixteen of 21 regions practiced universal hearing screening of 4-yearolds. Many different protocols were used. Professionals at child health care centers expressed a need for national guidelines for pre-school hearing screening. At the two and four-year follow-ups, one more region had introduced universal hearing screening of 4-year-olds, while two regions were planning to introduce it in 2019. The new national guidelines were well accepted and used throughout the country. CONCLUSION: There was a great variability in how pre-school hearing screening was performed in Sweden. Efforts are being made to provide uniform pre-school hearing screening. Cooperation between professionals in hearing health and health authorities is needed in order to broaden the use of universal pre-school hearing screening and to implement the new national guidelines.

Subperiosteal abscesses in acute mastoiditis in 115 Swedish children.

OBJECTIVES: To study the outcome of different surgical methods of treating subperiosteal abscesses resulting from acute mastoiditis. METHODS: Medical records for all children from a Swedish retrospective multicentre study, conducted between 1993 and 2007, with acute mastoiditis and subperiosteal abscess, but without predisposing diseases or other complications, were studied. A total of 115 children aged 0-16 years were identified. All patients had received intravenous antibiotics and most had undergone myringotomy. RESULTS: Thirty-three children had been treated with only minor interventions such as retroauricular needle aspiration and/or incision, while 67 had undergone mastoidectomy. Fifteen had undergone both needle aspiration and mastoidectomy. The group treated with needle aspiration/incision was compared with those treated with mastoidectomy. One of the few significant differences found between the groups was a longer hospital stay in the group that had undergone mastoidectomy. CONCLUSIONS: Retroauricular needle aspiration and/or incision combined with intravenous antibiotics and myringotomy was an effective first-line treatment for subperiosteal abscesses resulting from acute mastoiditis. In this retrospective study, no greater risk of further complications was seen in this group compared to the group in which mastoidectomy was performed.

Collagen Type II is produced in healing pars tensa of perforated tympanic membranes: an experimental study in the rat.

HYPOTHESIS: Type II collagen is synthesized in the tympanic membrane during healing of a perforation. The time course and appearance of Type II collagen regrowth in the newly healed tympanic membrane is the subject of the present study. BACKGROUND: The arrangement of Type II collagen fibers in the tympanic membrane gives it a unique tensile strength important for sound conduction. Healing after tympanic membrane perforation can cause the tympanic membrane to lose its characteristic. At what phase Type II collagen in tympanic membrane is replaced during healing of a perforation has previously not been studied. METHODS: Rat tympanic membranes were perforated, and the animals were sacrificed 9 to 16 days after perforation. Tympanic membranes were stained with a Type II collagen antibody. RESULTS: At Day 9, a majority of the tympanic membranes had healed. Keratinizing epithelium and connective tissue had formed, but there was no Type II collagen. At Day 10, all tympanic membranes had healed, and staining for Type II collagen appeared. After Day 10, staining was more intense. Newly formed collagen did not show the parallel bundle arrangement seen in normal tympanic membranes but was more scattered in the tissue. CONCLUSION: Type II collagen was seen in tympanic membranes only after closure of the perforation. The fiber arrangement after healing was disturbed, which presumably has an impact on the function of the tympanic membrane. Understanding the formation of Type II collagen in the healing of tympanic membrane perforations could enable further research toward treating tympanic membrane perforations.

Recurrent acute mastoiditis - a retrospective national study in Sweden.

CONCLUSIONS: Recurrences were seen in 5% of all patients with acute mastoiditis (AM). Mastoidectomy had been performed in the majority of the patients with recurrences at their first episode of AM. Compared with the group with a single episode of AM, the recurrent group exhibited more subperiosteal and ear canal abscesses, although they were not more severely ill. It appears from this study that previous mastoidectomy itself could predispose patients to recurrent AM (rAM), perhaps due to easier access to the mastoid cavity and/or due to a reduction in mucosal lining. OBJECTIVE: To retrospectively study the incidence and characteristics of rAM in Sweden. METHODS: Data from patients with rAM were reviewed and compared with data from patients with a single episode of AM during 1993-2007 in 33 ear, nose and throat departments in Sweden. RESULTS: Of 798 cases fulfilling the criteria for AM, 36 patients (5%) had experienced one or more recurrences, of which 4 patients (11%) had concurrent cholesteatoma. More than 50% of the patients had their first episode of AM before the age of 2 years. There was a highly significant difference between the two groups concerning the frequency of mastoidectomies and subperiosteal/retroauricular abscesses. However, other clinical characteristics, including severe complications, did not differ significantly. The majority of recurrences were treated conservatively with myringotomy and intravenous antibiotics, and also with aspiration/incision if a subperiosteal/retroauricular abscess was present.

Acute mastoiditis in children aged 0-16 years--a national study of 678 cases in Sweden comparing different age groups.

OBJECTIVE: To compare the characteristics of acute mastoiditis in children in different age groups in order to identify risk groups and risk factors for acute mastoiditis. METHODS: Records for all children aged 0-16 years treated for acute mastoiditis during 1993-2007 at 33 Ear, Nose and Throat departments in Sweden were reviewed retrospectively according to defined criteria for acute mastoiditis. RESULTS: A total of 678 cases fulfilled the inclusion criteria. Acute mastoiditis was most common in children younger than two years of age and this group was characterized by less prior history of other diseases and ear diseases, fewer visits to health care centers and less antibiotic treatment before admission, shorter duration of symptoms before admission, hospitalization for fewer days and lower frequency of complications and mastoidectomies. These children also showed a higher incidence of clinical findings, increased inflammatory markers such as fever and heightened counts of C-reactive protein and white blood cells compared with older children. They also tested positive for significantly more samples of Streptococcus pneumoniae while the older children more often exhibited growth of Streptococcus pyogenes or Pseudomonas aeruginosa or no microbial growth. CONCLUSIONS: The characteristics of pediatric acute mastoiditis differed significantly between age groups. Acute mastoiditis was most common in children younger than two years of age. They showed more rapid progress of symptoms and more distinct signs of acute mastoiditis. This is probably the reason why parents rapidly seek medical care for small children and hospital treatment thus starts earlier in the youngest children, which may in turn explain the excellent outcome. This study showed that younger children have neither more severe acute mastoiditis nor more complications than older ones. The differences between age groups suggest that there are distinctions in the pathophysiology behind the onset and course of acute mastoiditis in younger and older children.

Acute mastoiditis in children in Sweden 1993-2007--no increase after new guidelines.

OBJECTIVE: To study whether the incidence and characteristics of acute mastoiditis in children changed in Sweden following the introduction of new guidelines for diagnosis and treatment of acute otitis media advocating "watchful waiting" as an option in children 2-16 years of age with uncomplicated acute otitis media. METHODS: The records for all patients treated for mastoiditis during 1993-2007 at all Ear, Nose and Throat departments in Sweden were reviewed retrospectively according to defined criteria for acute mastoiditis. In this study the data from children aged 0-16 years were analyzed and compared 71/2 years before and 71/2 years after the introduction of the new guidelines in 2000. RESULTS: A total of 577 cases aged 0-16 years fulfilled the inclusion criteria during the whole study period. Cases involving cholesteatoma were excluded. The number of children affected by acute mastoiditis did not increase after the introduction of new guidelines. Acute mastoiditis was most common in children younger than two years of age. The proportion of acute mastoiditis increased after 2000 in the group aged 2-23 months although they were not affected concerning treatment by the new guidelines. No decrease was found in the frequency of prehospital antibiotic treatment among the children admitted with acute mastoiditis, and no increase was seen in the duration of ear symptoms before hospital admission, duration of hospital stay, or in the frequency of complications or mastoidectomies, after the introduction of the new guidelines in either group of children. CONCLUSIONS: The incidence of acute mastoiditis in children in Sweden did not increase following the introduction of new guidelines in 2000 for the diagnosis and treatment of acute otitis media. This is despite the fact that a significant decrease in antibiotic prescriptions for otitis media has been reported during the same time period. The characteristics of acute mastoiditis reflecting severity of illness did not change over time. Acute mastoiditis was most common and increased after 2000 only in children younger than two years of age in which antibiotics were still recommended in all cases of acute otitis media.

Acute mastoiditis in southern Sweden: a study of occurrence and clinical course of acute mastoiditis before and after introduction of new treatment recommendations for AOM.

Watchful waiting was recommended as an option for uncomplicated episodes of acute otitis media in Sweden in the year 2000. Concern was raised that these recommendations would lead to a higher incidence of acute mastoiditis. The aim of this study was to map the occurrence, treatment policy and the clinical course of mastoiditis before and after the new treatment recommendations were introduced. Included in the study were all patients (adults and children) who were admitted to two ENT departments in southern Sweden for acute mastoiditis from 1996 to 2005. A total of 42 cases of mastoiditis were identified: 23 during the first period of 1996-2000 and 19 during 2001-2005. Mastoidectomy was performed in 14 patients during the first period and in 8 during the second period. As much as 39% of mastoiditis patients received antibiotics before hospital care, but had no improvement. There was no indication that the number of patients with acute mastoiditis was increasing after new treatment recommendation of AOM. There was no increase in the occurrence of mastoidectomy. Severe complications of mastoiditis were rare. Although there were potentially threatening complications of mastoiditis in the study, these did not lead to sequelae. It is important to follow up the consequences when treatment recommendations of AOM are changed.

The collagen structure of the tympanic membrane: collagen types I, II, and III in the healthy tympanic membrane, during healing of a perforation, and during infection.

OBJECTIVE: To analyze the distribution of 3 collagen types in healthy tympanic membranes, during healing of a perforation, and during infection. DESIGN: Immunohistochemical study of collagen types I, II, and III in the tympanic membranes of healthy rats as well as during healing of a perforation and in the presence of infection with Streptococcus pneumoniae at various time points. SETTING: Laboratory research center at a university hospital. RESULTS: Type II collagen was a main constituent of the lamina propria of the pars tensa, whereas type I collagen was found mainly in the pars flaccida. Collagen types I and III were found at the insertion to the malleus handle and in the loose connective tissue surrounding the main collagen layer of the pars tensa. After myringotomy, collagen types I and III were found at the perforation border and around dilated blood vessels early in the healing phase. During infection, the collagen layer was thickened and stained strongly for type II collagen. Collagen types I and III were found in the edematous connective tissue around the main collagen layer and around dilated blood vessels. Three months after perforation or infection, all 3 collagens were present in the lamina propria of the tympanic membrane. Extensive amounts of all 3 collagen types were present in the scar tissue in the tympanic membranes of rats that had undergone myringotomy during the presence of acute otitis media. CONCLUSIONS: The lamina propria of the pars tensa is mainly made up of type II collagen, whereas type I collagen is found in the pars flaccida. Thus the fibrous structure of the pars tensa and flaccida is composed of diverse collagen types, which reflects the different physiological properties of these tissues. Collagen types I and III are present in the acute healing phase after myringotomy and infection, and the collagen content of the tympanic membrane is modified during the inflammatory and healing process.