Low-Frequency Hearing Loss: Auditory Brainstem Response-Derived Band Analysis

Conventional (0.125-8 kHz) and high-frequency (8-20kHz) audiometry, together with brainstem response audiometry supplemented with derived-band studies have been performed in 6 patients with sensorineural hearing loss: 1 with narrow-band, 3-4 kHz, and 5 with low-frequency threshold elevations. The derived-band results in the latter indicate that the low-frequency audiometric thresholds are spurious, and represent the low-frequency tails of viable high-frequency neurons. Threshold preservation in the 4- to 8-kHz frequency band proved necessary for generation of a normal auditory brainstem response at suprathreshold stimulus levels.

On a étudié sur 6 patients présentant une surdité de perception l'audiogramme conventionnel (0.125-8 kHz) et haute-fréquence (8-20 kHz), ainsi que les potentiels précoces dérivés: l'élévation de seuil était limitée à une bande étroite, 3-4 kHz, chez 1 patient, et intéressait les basses fréquences pour les 5 autres. La technique des potentiels dérivés sur ces derniers sujets montre que les seuils audiométriques sur les graves sont faux et représentent en fait les extrémités basse-frequence de neurones haute-fréquence demeurés sains. La préservation de l'audition au niveau de la bande 4-8 kHz est nécessaire à l'obtention de potentiels précoces normaux aux niveaux supraliminaires.     

Behaviour of High-Frequency Hearing in Noise

Because of an improved coupling and of special loudspeakers high-frequency (HF) audiometry may now be used for routine audiometry. Examinations of 200 weaving-mill workers showed hearing threshold levels with a broad dip at about 4 or 6 kHz but with relatively good hearing at about 11 and 12 kHz. The greatest hearing threshold shifts were observed at 15 kHz and above. The course of the curves clearly showed a dependence on the noise level. With most cases of acute acoustic traumata there was a total loss in the HF range reaching far into the frequency range of normal hearing. This pattern is correlated with the area of destruction of the hair cells in the cytocochleogram. Another characteristic course of the curves was marked by an extreme hearing loss in the HF range showing, however, a horizontal course. A similar cytohistogram could not be found in the literature.     

The Role of High-Frequency Audiometry in Early Detection of Ototoxicity

Ototoxicity is one of the unwanted side-effects of a number of medical drugs. As ototoxicity appears to be most pronounced in the higher frequencies, it can be assessed at an earlier stage by using high-frequency audiometry from 8 to 20 kHz. We have investigated the precision of these measurements. In spite of inaccuracies of headphone positioning, which may influence especially the high-frequency thresholds, standard deviations for frequencies above 8 kHz were obtained that were nearly as small as for audiometry up to 8 kHz. Age-related reference curves for the higher frequencies are presented. The results on 100 ears of patients treated with platinum-derivatives show the importance of high-frequency audiometry for the early detection of ototoxicity.

Certains médicaments ont un effet toxique sur l'oreille interne (ototoxicité). Cet effet se produit d'abord au niveau des hautes fréquences et peut ětre détecté plus töt par audiométrie dans les fréquences de 8 à 20 kHz que par audiométrie conventionnelle. Bien que la position des écouteurs sur la těte puisse influencer le seuil des hautes fréquences, nous avons obtenu des écarts-types presqu'aussi petits qu'avec audiométrie jusqu'à 8 kHz. Des courbes de référence en fonction de l'aˇge sont présentées. L'importance de l'audiométrie dans les hautes fréquences pour la détection précoce d'un effet ototoxique est démontrée à partir des résultats obtenus chez 100 malades traités par des dérivés du platine.     

Reliability of Auditory Brainstem Responses from Sequenced High-Frequency (≥ 8 kHz) Tonebursts

An auditory brainstem response method is described for evoking responses to 4 high-frequency (8, 10,12 and 14 kHz) tone-bursts in the same amount of time normally required to obtain responses to single tonebursts. Reliability of responses to high-frequency toneburst stimuli presented in the conventional manner (one at a time) has been previously documented. In the present study, high-frequency tonebursts were presented to 20 normal-hearing subjects singly and in a 4-stimulus sequence. The reliability of resulting responses did not differ significantly between single- and multiple-stimulus test conditions. It is concluded that this sequenced-stimulus concept could be developed for use in serial monitoring of individuals receiving ototoxic agents as well as being broadly applicable to clinical situations in which patients cannot or will not respond voluntarily.     

Ventilation modalities in infants with congenital diaphragmatic hernia

Neonates with congenital diaphragmatic hernia are among the more complex patients to support with mechanical ventilation. They have particular features that add to the difficulties already present in the neonatal patient. A ventilation strategy tailored to the patient’s underlying physiology rather than mode of ventilation is a crucial issue for clinicians treating these delicate patients.     

乳管内窥镜联合高频超声定位法与传统定位法在乳头状瘤手术中的应用比较

目的研究乳管内窥镜与高频超声在乳头状瘤术前联合应用的临床意义。方法将有母乳喂养需求的73例乳腺导管内乳头状瘤患者随机分为两组,对照组33例采用传统美蓝定位法或乳管扩张器定位法手术,研究组40例采用乳管镜联合高频超声定位法进行肿瘤手术,比较乳管镜联合高频超声定位法与传统定位法的误诊率,观察和比较患者产后乳汁分泌情况。结果两组患者比较,研究组误诊率(7.50%)明显低于对照组(24.24%),术后研究组10例、对照组8例正常哺乳,乳汁分泌正常率分别为90.00%和37.50%。结论乳管内窥镜联合高频超声定位法比传统的定位法在乳腺中小导管内乳头状瘤的手术治疗中具有更优势的效果,不仅能够减少手术损伤、获得准确定位,还能最大程度地满足哺乳期妇女正常产奶的愿望,并保持乳房对称与完好曲线,适合于临床推广。     

High-Frequency Micro-Ultrasound Imaging and Optical Topographic Imaging for Spinal Surgery: Initial Experiences

High frequency micro-ultrasound (µUS) transducers with central frequencies up to 50?MHz facilitate dynamic visualization of patient anatomy with minimal disruption of the surgical work flow. Micro-ultrasound improves spatial resolution over conventional ultrasound imaging from millimeter to micrometer, but compromises depth penetration. This trade-off is sufficient during an open surgery in which the bone is removed and theultrasound probe can be placed into the surgical cavity. By fusing µUS with pre-operative imaging and tracking the ultrasound probe intra-operatively using our optical topographic imaging technology, we can provide dynamic feedback during surgery, thus affecting clinical decision making. We present our initial experience using high-frequency µUS imaging during spinal procedures. Micro-ultrasound images were obtained in five spinal procedures. Medical rationale for use of µUS was provided for each patient. Surgical procedures were performed using the standard clinical practice with bone removal to facilitate real-time ultrasound imaging of the soft tissue. During surgery, the µUS probe was registered to the pre-operative computed tomography and magnetic resonance images. Images obtained comprised five spinal decompression surgeries (four tumor resections, one cystic synovial mass). Micro-ultrasound images obtained during spine surgery delineated exquisite detailing of the spinal anatomy including white matter and gray matter tracts and nerve roots and allowed accurate assessment of the extent of decompression/tumor resection. In conclusion, tracked µUS enables real-time imaging of the surgical cavity, conferring significant qualitative improvement over conventional ultrasound.     

Posture-cognitive dual-tasking: A relevant marker of depression-related psychomotor retardation. An illustration of the positive impact of repetitive transcranial magnetic stimulation in patients with major depressive disorder

This study examined whether postural control variables, particularly the center-of-pressure (COP) velocity-based parameters, could be a relevant hallmark of depression-related psychomotor retardation (PMR). We first aimed at investigating the interplay between the PMR scores and the COP performance in patients with major depressive disorder (MDD), as compared to age-matched healthy controls; secondly, we focused on the impact of a repetitive transcranial magnetic stimulation (rTMS) treatment on depression, PMR scores and postural performance. 16 MDD patients, and a control group of 16 healthy adults, were asked to maintain quiet standing balance during two trials with or without vision, and while backward counting (dual task). All the position and velocity-based COP variables were computed. Before and after the rTMS session (n eligible MDD = 10), we assessed the depression level with the Montgomery–Asberg Depression Rating Scale (MADRS), the PMR scores with the French Retardation Rating Scale for Depression (ERD), and postural performance. Before the treatment, significant positive partial correlations were found between the pre-ERD scores and the velocity-based COP variables, especially in the dual-task conditions (p < 0.05). In contrast, there was no significant correlation between the post-ERD scores and any postural parameter after the treatment. The MADRS and ERD scores showed a significant decrease between before and after the rTMS intervention. For the first time, the findings clearly validated the view that the assessment of postural performance - easy to envisage in clinical settings-constitutes a reliable and objective marker of PMR in MDD patients.