Search

Localisation of low- and high-frequency sounds in single-sided deaf cochlear implant users was investigated using noise stimuli designed to mitigate monaural localisation cues. Within subject design. Sound source localisation was tested in the horizontal plane using an array of seven loudspeakers along the azimuthal angle span from −90° to +90°. Stimuli were broadband noise and high- and low-frequency noise. Twelve adult subjects with single-sided deafness participated in the study. All had normal hearing in the healthy ear and were supplied with a cochlear implant (CI) in their deaf ear. With broadband noise, the mean angular localisation error was 39° in aided condition as compared to a median angular error of 83.6° when the speech processor was not worn. For high-frequency noise, the median angular error was 30° and for low-frequency noise, it was 46° in the CI-aided condition. Single-sided deaf CI users show the best sound localisation for high-frequency sounds. This supports the view that interaural level differences are dominant for sound localisation in these listeners. Nonetheless, a limited ability to localise low-frequency sounds was observed, which may be based on the supportive perception of interaural time differences. [ABSTRACT FROM AUTHOR]

Objectives: Patients with profound hearing loss can be supported by a cochlear implant (CI) to restore hearing. The development of hearing with CI, especially concerning speech comprehension, is subject to constant changes associated with several plasticity effects in the brain. These neural changes are not completely understood yet. In the present study neural processing mechanisms during speech comprehension of spoken and sung sentences will be investigated in order to assess potential effects of sentence melody. Material and methods: Brain activity was assessed via the simultaneous application of two neuroscientific methods: the electroencephalography (EEG) and the functional near-infrared spectroscopy (fNIRS). The former is able to measure very fast modulations in the brain in the range of milliseconds, while the latter can identify increased activity of underlying brain areas. By means of this multi-methodological approach, we assessed brain activity while patients supplied with a cochlear-implant listened to semantically correct and incorrect sentences. Each sentence was presented in a spoken or sung modality. A group of normal- hearing listeners was additionally tested with the same experiment as a reference group. Results: Results from EEG as well as fNIRS in normal-hearing subjects show comparable processing for spoken and sung sentences. The EEG, in particular, shows an increased N400 component for semantically incorrect compared to correct sentences. CI-patients reveal differential amplitudes of specific EEG markers as well as distinct activation patterns in the fNIRS signal. Conclusions: First results from this study suggest an affected differentiation ability between semantically correct and incorrect sentences as well as between spoken and sung sentences in CI users. Thus, patients show at least partially altered neural processing mechanisms and brain plastictity effects. [ABSTRACT FROM AUTHOR]

Objective: In patients with asymmetric hearing loss, the ability to localize sounds in space is very limited. The main reason is a distortion of binaural processing in the human brain due to the unbalanced transmission of the signals received from both ears to the neural system. In case of severe asymmetric hearing loss patients are often supplied with a hearing aid on one side and a cochlear implant on the other side. By this bimodal stimulation, an improvement of binaural listening tasks is expected. However, listening performance in conditions requiring binaural processing is still far below that of normal-hearing listeners. One of the reasons could be a temporal mismatch of signal processing in the hearing aid compared to the cochlear implant (CI) which may result in desynchronization of the input signals to the neural system when different devices are worn. The goal of the present study was to investigate the mechanisms of binaural hearing regarding sound localization in patients with bimodal stimulation and to compensate for the temporal mismatch. Material: In total 10 patients participated in the study. All of them suffered from asymmetric hearing loss and were supplied with a hearing aid and a cochlear implant. Methods: Sound source localization tests were performed in an anechoic chamber equipped with an array of seven loudspeakers in the frontal plane. Synchronization of the input signals to the neural system was performed by delaying the signal of the cochlear implant as signal transmission to the neural system via cochlear implant occurs a few milliseconds faster than transmission via hearing aid. Prior to testing the processing time of the hearing aid was estimated based on electroacoustic measurements in a test box. These tests were performed individually for each device in conditions of everyday settings used by the patient. Localization tests were performed subsequently for 5 delay times of signal processing in the CI: delay of the CI signal equal to hearing aid processing time and delay of CI varied between hearing aid processing time by ±1 ms and ±2 ms. In addition, one sound localization test in the daily used bimodal listening condition without delay of CI signal was performed as reference. Results: Significant differences were found between wearing the hearing aid only and the bimodal listening condition. In the unilateral condition with hearing aid alone, the angular localization error was at chance level in the majority of the patients. In the bimodal reference condition (without delay) an angular localization error of about 40° was observed. The delay of the cochlear implant signal had a significant effect on the sound localization performance of the patients. In particular, the angular error was lower in all of the delay conditions, between 32 and 36°. However, the effect was small and interindividual variability was large depending on the hearing disorder and the setting of the hearing aid. Conclusions: Timing of stimulation does affect sound localization in bimodal listeners. Hence, optimization of stimulation timing in bimodal listeners potentially enhances localization accuracy and lowers bias of sound localization in patients supplied with hearing aid and cochlear implant. [ABSTRACT FROM AUTHOR]

We conducted a prospective study in order to determine planned pregnancy outcome in systemic lupus erythematosus followed in a tertiary referral centre. Pregnancy was authorized if disease was inactive on 20 mg/day prednisone or less for at least 1 yr. Upon the diagnosis of pregnancy, systematic corticosteroids consisting of 10 mg/day prednisone or more were started. In the case of antiphospholipid antibodies, 100 mg/day aspirin was added, replaced by heparin in the pre-partum period. In the case of antiphospholipid syndrome complicated by previous thrombotic events or fetal losses despite aspirin, heparin was prescribed. One woman with a history of atrioventricular block was treated with dexamethasone. Patients were monitored by medical and obstetrical examination, and laboratory tests carried out at least monthly and a quarterly echography. Among 62 pregnancies in 38 women, lupus flare was observed in 27% of the cases, 6% of which occurred in the post-partum period. Flares were moderate except in one renal involvement in a woman with prior diffuse proliferative glomerulonephritis. Therapy was not modified in half of the cases. Pregnancy ended in early spontaneous abortion not related to lupus flare (n = 10), stillbirth (n = 2). induced abortion (n = 2), preterm birth (n = 29) and full-term birth (n = 19). Caesarean section was performed in nine cases. A severe infection occurred in two premature neonates. Another premature neonate was growth retarded. Two children had cutaneous neonatal lupus. No child died, neither had atrioventricular block. Stillbirth and severe prematurity were more common in mothers with antiphospholipid syndrome. After exclusion of early spontaneous and induced abortions, the live birth rate was 96%, that is close to the French general population. The main problem remains a high rate of prematurity, but without maternal or neonatal death. [ABSTRACT FROM PUBLISHER]