A probabilistic poisson-based model accounts for an extensive set of absolute auditory threshold measurements

Publication date: Available online 27 June 2017
Source:Hearing Research
Author(s): Peter Heil, Artur Matysiak, Heinrich Neubauer
Thresholds for detecting sounds in quiet decrease with increasing sound duration in every species studied. The neural mechanisms underlying this trade-off, often referred to as temporal integration, are not fully understood. Here, we probe the human auditory system with a large set of tone stimuli differing in duration, shape of the temporal amplitude envelope, duration of silent gaps between bursts, and frequency. Duration was varied by varying the plateau duration of plateau-burst (PB) stimuli, the duration of the onsets and offsets of onset-offset (OO) stimuli, and the number of identical bursts of multiple-burst (MB) stimuli. Absolute thresholds for a large number of ears (>230) were measured using a 3-interval-3-alternative forced choice (3I-3AFC) procedure. Thresholds decreased with increasing sound duration in a manner that depended on the temporal envelope. Most commonly, thresholds for MB stimuli were highest followed by thresholds for OO and PB stimuli of corresponding durations. Differences in the thresholds for MB and OO stimuli and in the thresholds for MB and PB stimuli, however, varied widely across ears, were negative in some ears, and were tightly correlated. We show that the variation and correlation of MB-OO and MB-PB threshold differences are linked to threshold microstructure, which affects the relative detectability of the sidebands of the MB stimuli and affects estimates of the bandwidth of auditory filters. We also found that thresholds for MB stimuli increased with increasing duration of the silent gaps between bursts. We propose a new model and show that it accurately accounts for our results and does so considerably better than a leaky-integrator-of-intensity model and a probabilistic model proposed by others. Our model is based on the assumption that sensory events are generated by a Poisson point process with a low rate in the absence of stimulation and higher, time-varying rates in the presence of stimulation. A subject in a 3I-3AFC task is assumed to choose the interval in which the greatest number of events occurred or randomly chooses among intervals which are tied for the greatest number of events. The subject is further assumed to count events over the duration of an evaluation interval that has the same timing and duration as the expected stimulus. The increase in the rate of the events caused by stimulation is proportional to the time-varying amplitude envelope of the bandpass-filtered signal raised to an exponent. We find the exponent to be ∼3, consistent with our previous studies. This challenges models that are based on the assumption of the integration of a neural response that is directly proportional to the stimulus amplitude or proportional to its square (i.e., proportional to the stimulus intensity or power).

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Range and Precision of Formant Movement in Pediatric Dysarthria

Purpose

This study aimed to improve understanding of speech characteristics associated with dysarthria in children with cerebral palsy by analyzing segmental and global formant measures in single-word and sentence contexts.

Method

Ten 5-year-old children with cerebral palsy and dysarthria and 10 age-matched, typically developing children participated in this study. Vowel space area and second formant interquartile range were measured from children’s elicited productions of single words and sentences.

Results

Results showed that the children with dysarthria had significantly smaller vowel space areas than typically developing children in both word and sentence contexts; however, overall ranges of second formant movement did not differ between groups in word or sentence contexts. Additional analysis of single words revealed that, compared to typical children, children with dysarthria had smaller second formant interquartile ranges in single words with phonetic contexts requiring large changes in vocal tract configuration, but not in single words with monophthongs.

Conclusions

Results of this study suggest that children with dysarthria may not have globally reduced ranges of articulatory movement compared to typically developing peers; however, they do exhibit reduced precision in producing phonetic targets.

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Do antiplatelet drugs increase the risk of bleeding after tooth extraction? A case-crossover study

Publication date: Available online 26 June 2017
Source:International Journal of Oral and Maxillofacial Surgery
Author(s): F. Akhlaghi, I. Khaheshi, S. Amirhassani, R. Tabrizi
The aim of this study was to assess the risk of bleeding after tooth extraction in patients taking aspirin or clopidogrel. This case-crossover study evaluated patients taking aspirin (80mg/day) or clopidogrel (75mg/day) and undergoing tooth extraction. In the first session, extraction was performed without discontinuing aspirin (group 1) or clopidogrel (group 2). In the second session, patients ceased using antiplatelet drugs 5days prior to tooth extraction. Bleeding was evaluated using a visual analogue scale (VAS) for 72h after tooth extraction. The platelet function assay (PFA) was performed for group 1 and flow cytometry assessment of vasodilator-stimulated phosphoprotein (VASP) was performed for group 2, in both sessions. Thirty-eight patients were studied: 20 in group 1 and 18 in group 2. Analysis of the data did not demonstrate any difference in bleeding severity between sessions 1 and 2 in either group (P>0.05). There was a significant difference between sessions 1 and 2 in group 1 for the mean collagen/epinephrine membrane closure time (PFA) (P=0.001). A significant difference in platelet reactivity index (flow cytometry for VASP) was noted between sessions 1 and 2 in group 2 (P=0.001). According to this case-crossover study, dental extraction can be performed safely without withdrawal of aspirin or clopidogrel.

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Intraoral vertico-sagittal ramus osteotomy: modification of the L-shaped osteotomy

Publication date: Available online 26 June 2017
Source:International Journal of Oral and Maxillofacial Surgery
Author(s): J. Iwanaga, S. Kikuta, M. Nakamura, A. Koba, K. Ogata, S. Toyofuku, R.S. Tubbs, J. Kusukawa
The sagittal split ramus osteotomy and intraoral vertical ramus osteotomy carry the potential risk of postoperative nerve paralysis, bleeding, and fracture and dislocation of the condyle. In 1992, Choung first described the intraoral vertico-sagittal ramus osteotomy for the purpose of avoiding postoperative dislocation of the condyle. However, there is still potential for damaging the inferior alveolar nerve and maxillary artery with this technique. The authors have developed a modified technique to minimize these risks. An evaluation of surgical experience and patient outcomes with the use of this technique is presented herein. One hundred twenty-two sides in 97 Japanese patients diagnosed with a jaw deformity were analyzed. This technique includes a horizontal osteotomy that is performed at a higher position than in the original Choung procedure. Intraoperatively, there was no unexpected bleeding from the operative site. Proximal segment dislocation from the glenoid fossa was observed on one side (0.82%). Non-union of the osteotomy was not observed in any patient. Intraoperative fracture of the coronoid process occurred in 2.46%, but none necessitated treatment of the fracture. Nerve dysfunction was found in 2.46% at the 12-month postoperative follow-up. The modified technique presented herein was developed to reduce postoperative nerve dysfunction and intraoperative hemorrhage.

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The application of a delayed expansion technique for horizontal alveolar ridge augmentation in dental implantation

Publication date: Available online 26 June 2017
Source:International Journal of Oral and Maxillofacial Surgery
Author(s): X. Li, P. Xu, X. Xu, S. Liu
The aim of this study was to evaluate the application of delayed expansion of the alveolar ridge in dental implantation. This method avoids the need to harvest autogenous bone and the requirement to fix a block with screws, and could help prevent the uncontrolled fracture and avascular necrosis that may result from the traditional alveolar split. Eighteen patients and 43 implants were included in this retrospective study. The width of the alveolar ridge was measured before implantation, immediately after implantation, and after the final restoration. The width increased significantly after the insertion of implants and decreased slightly after bone remodelling. Overall, the width of the alveolar ridge increased by 2.37±1.44mm on average, ranging from −0.20mm to 5.75mm. The results suggest the use of delayed expansion for horizontal alveolar bone augmentation; however, the maxillary premolar area may not be a suitable site.

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Early hematopoietic stem cell transplantation in a patient with severe mucopolysaccharidosis II: A 7 years follow-up.

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Early hematopoietic stem cell transplantation in a patient with severe mucopolysaccharidosis II: A 7 years follow-up.

Mol Genet Metab Rep. 2017 Sep;12:62-68

Authors: Barth AL, de Magalhães TSPC, Reis ABR, de Oliveira ML, Scalco FB, Cavalcanti NC, Silva DSE, Torres DA, Costa AAP, Bonfim C, Giugliani R, Llerena JC, Horovitz DDG

Abstract

Mucopolysaccharidosis type II (MPS II – Hunter syndrome) is an X-linked lysosomal storage disorder caused by a deficiency in the enzyme iduronate-2 sulfatase (I2S), leading to the accumulation of the glycosaminoglycans, affecting multiple organs and systems. Enzyme replacement therapy does not cross the blood brain barrier, limiting results in neurological forms of the disease. Another option of treatment for severe MPS, hematopoietic stem cell transplantation (HSCT) has become the treatment of choice for the severe form of MPS type I, since it can preserve neurocognition when performed early in the course of the disease. To date, only few studies have examined the long-term outcomes of HSCT in patients with MPS II. We describe the seven-year follow-up of a prenatally diagnosed MPS II boy with positive family history of severe MPS form, submitted to HSCT with umbilical cord blood cells at 70 days of age. Engraftment after 30 days revealed mixed chimerism with 79% donor cells; after 7 years engraftment remains at 80%. I2S activity 30 days post-transplant was low in plasma and normal in leukocytes and the same pattern is observed to date. At age 7 years growth charts are normal and he is very healthy, although mild signs of dysostosis multiplex are present, as well as hearing loss. The neuropsychological evaluation (Wechsler Intelligence Scale for Children – Fourth Edition – WISC-IV), disclosed an IQ of 47. Despite this low measured IQ, the patient continues to show improvements in cognitive, language and motor skills, being quite functional. We believe that HSCT is a therapeutic option for MPS II patients with the severe phenotype, as it could preserve neurocognition or even halt neurodegeneration, provided strict selection criteria are followed.

PMID: 28649514 [PubMed – in process]

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Cost-effectiveness of Universal and Targeted Newborn Screening for Congenital Cytomegalovirus Infection.

https:--archpedi.jamanetwork.com-images- Related Articles

Cost-effectiveness of Universal and Targeted Newborn Screening for Congenital Cytomegalovirus Infection.

JAMA Pediatr. 2016 Dec 01;170(12):1173-1180

Authors: Gantt S, Dionne F, Kozak FK, Goshen O, Goldfarb DM, Park AH, Boppana SB, Fowler K

Abstract

Importance: Congenital cytomegalovirus (cCMV) infection is a major cause of childhood deafness. Most cCMV infections are not diagnosed without newborn screening, resulting in missed opportunities for directed care.

Objective: To estimate the cost-effectiveness of universal and targeted newborn cCMV screening programs compared with no cCMV screening.

Design, Setting, and Participants: Models were constructed using rates and outcomes from prospective cohort studies of newborn cCMV screening in US postpartum care and early hearing programs. Costs of laboratory testing, treatment, and hearing loss were drawn from Medicaid data and published estimates. The benefits of cCMV screening were assumed to come from antiviral therapy for affected newborns to reduce hearing loss and from earlier identification of hearing loss with postnatal onset. Analyses were performed from July 2014 to March 2016.

Interventions: Models compared universal or targeted cCMV screening of newborns with a failed hearing screen, with standard care for cCMV infection.

Main Outcomes and Measures: The incremental costs of identifying 1 cCMV infection, identifying 1 case of cCMV-related hearing loss, and preventing 1 cochlear implant; the incremental reduction in cases of severe to profound hearing loss; and the differences in costs per infant screened by universal or targeted strategies under different assumptions about the effectiveness of antiviral treatment.

Results: Among all infants born in the United States, identification of 1 case of cCMV infection by universal screening was estimated to cost $2000 to $10 000; by targeted screening, $566 to $2832. The cost of identifying 1 case of hearing loss due to cCMV was as little as $27 460 by universal screening or $975 by targeted screening. Assuming a modest benefit of antiviral treatment, screening programs were estimated to reduce severe to profound hearing loss by 4.2% to 13% and result in direct costs of $10.86 per newborn screened. However, savings of up to $37.97 per newborn screened were estimated when costs related to functionality were included.

Conclusions and Relevance: Newborn screening for cCMV infection appears to be cost-effective under a wide range of assumptions. Universal screening offers larger net savings and the greatest opportunity to provide directed care. Targeted screening also appears to be cost-effective and requires testing for fewer newborns. These findings suggest that implementation of newborn cCMV screening programs is warranted.

PMID: 27723885 [PubMed – indexed for MEDLINE]

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Smartphone hearing screening in mHealth assisted community-based primary care.

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Smartphone hearing screening in mHealth assisted community-based primary care.

J Telemed Telecare. 2016 Oct;22(7):405-12

Authors: Yousuf Hussein S, Wet Swanepoel D, Biagio de Jager L, Myburgh HC, Eikelboom RH, Hugo J

Abstract

INTRODUCTION: Access to ear and hearing health is a challenge in developing countries, where the burden of disabling hearing loss is greatest. This study investigated community-based identification of hearing loss using smartphone hearing screening (hearScreen™) operated by community health workers (CHWs) in terms of clinical efficacy and the reported experiences of CHWs.

METHOD: The study comprised two phases. During phase one, 24 CHWs performed community-based hearing screening as part of their regular home visits over 12 weeks in an underserved community, using automated test protocols employed by the hearScreen™ smartphone application, operating on low-cost smartphones with calibrated headphones. During phase two, CHWs completed a questionnaire regarding their perceptions and experiences of the community-based screening programme.

RESULTS: Data analysis was conducted on the results of 108 children (2-15 years) and 598 adults (16-85 years). Referral rates for children and adults were 12% and 6.5% respectively. Noise exceeding permissible levels had a significant effect on screen results at 25 dB at 1 kHz (p<0.05). Age significantly affected adult referral rates (p < 0.05), demonstrating a lower rate (4.3%) in younger as opposed to older adults (13.2%). CHWs were positive regarding the hearScreen™ solution in terms of usability, need for services, value to community members and time efficiency.

CONCLUSION: Smartphone-based hearing screening allows CHWs to bring hearing health care to underserved communities at a primary care level. Active noise monitoring and data management features allow for quality control and remote monitoring for surveillance and follow-up.

PMID: 26468215 [PubMed – indexed for MEDLINE]

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