Reproducibility of hearing threshold measurements. Supplementary data on bone-conduction and speech audiometry

The reproducibility of bone-conduction pure-tone audiometry and speech recognition thresholds has been tested in groups of normal-hearing subjects. Each person was tested twice during the same day, and the test-retest difference was calculated. The reproducibility is presented as the standard deviation of this difference. Bone-conduction threshold measurements have a high degree of test-retest precision, whereas air-bone gaps show a large range of distribution in these normal-hearing subjects. This makes the interpretation of such gaps spurious when values are below 20-30 dB. Speech recognition threshold has the highest degree of test-retest precision of all audiometric tests, and this is probably due to the steep slope of the psychometric function at 50% intelligibility. A more detailed graphic presentation of the 50% point of intersection will bring the reproducibility down to less than 2.5 dB.     

Early auditory-evoked responses in the cat: rate effects.

The brain-stem electric responses (BSER) of the cat have been evoked with a 4-kHz tone burst at three stimulus intensity levels, and at interstimulus intervals (ISI) varying fromm 500 to 20 ms. Response amplitude and latency have also been compared in different post-natal age groups, and in bilaterally hearing and unilaterally deaf animals. Increasing reptition rates produce greater latency changes in the youngest animals, whilst all age groups show amplitude decrement at shorter ISI, apart from wave III which increases in amplitude, particularly in bilaterally hearing cats at higher stimulus intensity levels. Wave I shows greater amplitude reduction than do the succeeding waves, which may indicate that the primary cochlear nuclei contribute to later waves of the BSER.     

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.     

Intra-rater variability in low-grade glioma segmentation

Assessment of size and growth are key radiological factors in low-grade gliomas (LGGs), both for prognostication and treatment evaluation, but the reliability of LGG-segmentation is scarcely studied. With a diffuse and invasive growth pattern, usually without contrast enhancement, these tumors can be difficult to delineate. The aim of this study was to investigate the intra-observer variability in LGG-segmentation for a radiologist without prior segmentation experience. Pre-operative 3D FLAIR images of 23 LGGs were segmented three times in the software 3D Slicer. Tumor volumes were calculated, together with the absolute and relative difference between the segmentations. To quantify the intra-rater variability, we used the Jaccard coefficient comparing both two (J2) and three (J3) segmentations as well as the Hausdorff Distance (HD). The variability measured with J2 improved significantly between the two last segmentations compared to the two first, going from 0.87 to 0.90 (p?=?0.04). Between the last two segmentations, larger tumors showed a tendency towards smaller relative volume difference (p?=?0.07), while tumors with well-defined borders had significantly less variability measured with both J2 (p?=?0.04) and HD (p?<?0.01). We found no significant relationship between variability and histological sub-types or Apparent Diffusion Coefficients (ADC). We found that the intra-rater variability can be considerable in serial LGG-segmentation, but the variability seems to decrease with experience and higher grade of border conspicuity. Our findings highlight that some criteria defining tumor borders and progression in 3D volumetric segmentation is needed, if moving from 2D to 3D assessment of size and growth of LGGs.

     

Stimulus waveforms used in brainstem response audiometry

Clicks and tone-bursts are the most widely used stimuli in brainstem response audiometry. The acoustic click waveform is not only dependent on electric pulse length, but also on the type of transducer, ear coupling and measuring method employed. On the other hand, acoustic tone-bursts are more precisely defined by the electric stimulus-parameters since they show less variation under the same experimental conditions. Acoustic cancellation with alternating polarity electric stimuli is also better with tone-bursts.     

Impact of age on survival after intensive therapy for multiple myeloma: a population-based study by the Nordic Myeloma Study Group

The value of intensive therapy, including autologous stem cell transplantation, in newly diagnosed myeloma patients >60 years is not clear. We evaluated the impact of age (<60 years vs. 60-64 years) on survival in a prospective, population-based setting and compared survival with conventionally treated historic controls. The prospective population comprised 452 patients registered between 1998 and 2000. Of these, 414 received intensive therapy. The historic population, derived from our most recent population-based study on conventional therapy, comprised 281 patients. Of these, 243 fulfilled our eligibility criteria for intensive therapy. For patients undergoing intensive therapy it was found that two factors, beta-2-microglobulin and age <60 years vs. 60-64 years, had independent prognostic impact on survival. However, compared with the historic controls a survival advantage was found both for patients <60 (median 66 months vs. 43 months, P < 0.001) and 60-64 years (median 50 months vs. 27 months; P = 0.001). We conclude that in a population-based setting higher age adversely influences outcome after intensive therapy. Our results indicate that intensive therapy prolongs survival also at age 60-64 years but with less superiority than in younger patients.     

Frailty assessment of older adults,first-time applicants of public home care service in Norway

ObjectiveEarly detection of frailty is essential to prevent or delay disability. The most appropriate screening tool for frailty among home-dwelling older adults is under debate. The present study estimates the prevalence of frailty among older adults, first-time applicants of public home care service in Norway, and investigates the appropriateness of gait speed and Short Physical Performance Battery as screening-tools for frailty.Design and settingWe conducted a cross-sectional study of 116 older adults >65 years applying for public home care service for the first time. Frailty was assessed by an adapted version of the Fried Frailty Phenotype. The test accuracies of gait speed and Short Physical Performance Battery to detect frailty were calculated for a general population >70 years in Norway.Results62.1% of the participants were frail, 29.3% were prefrail, and 8.6% were robust. Mean gait speed and Short Physical Performance Battery-scores were significantly lower in frail compared to prefrail individuals, and significantly lower in prefrail compared to robust individuals. The sensitivity and specificity of gait speed at a cut point of 0.8 m/s to detect physical frailty phenotype was 99% and 68%, respectively.Conclusions The high prevalence of frailty in the present study indicates that screening for frailty should be considered at an earlier time point than when older adults apply for public home care service for the first time. Gait speed may be an appropriate screening tool for frailty in a general population >70 years in Norway.

KEY POINTS

• The prevalence of frailty among older adults, first-time applicants of public home care services in Norway is major.
• Screening for frailty should be considered before older adults apply for public home care service for the first time.
• Gait speed at a cut point at 0.8 m/s may be an appropriate screening tool for frailty in a general population >70 years in Norway.

     

Low-frequency auditory brainstem response threshold

Auditory brainstem thresholds have been determined in 35 non-cooperative, anaesthetized children using a 'two-point audiogram' paradigm. The high-frequency point was found with a 2 kHz tone-burst without masking, and the low-frequency with a 0.5 kHz tone-burst together with 1 kHz high-pass noise masking. Great variability was found in the low-frequency thresholds, and only 3 of 18 ears with normal high-frequency thresholds had low-frequency thresholds below 70 dB nHL. It is concluded that the 0.5 kHz tone-burst with 1 kHz high-pass noise masking is not a reliable method for routine assessment of low-frequency auditory threshold at the brainstem level.     

Early Auditory-Evoked Responses in the Cat: Rate Effects

The brain-stem electric responses (BSER) of the cat have been evoked with a 4-kHz tone burst at three stimulus intensity levels, and at interstimulus intervals (ISI) varying from 500 to 20 ms. Response amplitude and latency have also been compared in different post-natal age groups, and in bilaterally hearing and unilaterally deaf animals. Increasing repetition rates produce greater latency changes in the youngest animals, whilst all age groups show amplitude decrement at shorter ISI, apart from wave III which increases in amplitude, particularly in bilaterally hearing cats at higher stimulus intensity levels. Wave I shows greater amplitude reduction than do the succeeding waves, which may indicate that the primary cochlear nuclei contribute to later waves of the BSER.

Nous avons recherché chez 16 chats les réponses électriques du tronc cérébral (BSER) en utilisant des tone-bursts de 4 kHz, à trois niveaux d'intensité et à des intervalles inter-stimuli (ISI) variant de 500 à 20 ms. L'amplitude des réponses et leur latence ont été comparérs dans des groupes d'aˇge différent, chez des animaux jouissant d'une audition bilatérale normale, et chez des animaux atteints de surdité unilatérale. En augmentant la fréquence des répétitions, nous avons observé une augmentation plus marquée des temps de latence chez les animaux les plus jeunes, tandis que dans tous les groupes d'aˇge apparaiˇt une diminution de l'amplitude pour des ISI de plus en plus courts, sauf pour l'onde III, dont l'amplitude augmente aux niveaux d'intensité les plus élevés, particulièrement chez les chats à audition bilatérale normale. La réduction d'amplitude plus importante pour l'onde I que pour les ondes suivantes pourrait indiquer que le premier noyau cochléaire contribue à la formation des ondes tardives des BSER.     

Long-term cryopreservation of autologous stem cell grafts: a clinical and experimental study of hematopoietic and immunocompetent cells

BACKGROUND: Autologous stem cell transplantation (ASCT) is used in the treatment of several malignancies. Harvesting sufficient peripheral blood progenitor cells (PBPCs) for a potential second autotransplantation at the time of relapse several years after diagnosis is becoming an increasingly common practice.
STUDY DESIGN AND METHODS: Cryopreserved PBPCs were prepared with different concentrations of dimethyl sulfoxide (DMSO; 2, 4, 5, and 10%) and stored for at least 5 years before the recovery of CD34+ cells and various T- and natural killer (NK)-cell subsets were analyzed by flow cytometry. Furthermore, clinical variables for myeloma patients having a second autotransplantation with long-term-stored autografts were evaluated.
RESULTS: The number of viable CD34+ cells in long-term-stored grafts was higher when autografts were cryopreserved with 4 or 5% than with 2 and 10% DMSO. The number of viable CD34+ cells was reduced by 13.9% after 5 years of cryostorage in 5% DMSO. Lymphocyte viability was also higher with 4 or 5% DMSO. However, the frequencies of several T-cell subsets showed DMSO-dependent differences, whereas NK-cell subsets did not. Furthermore, after a second autotransplantation with long-term-stored PBPC grafts at the time of myeloma relapse (median storage time, 42 months) all 17 patients reached neutrophil counts exceeding 0.5 × 10⁹/L and platelet counts exceeding 20 × 10⁹/L within 15 days. There was no difference in engraftment between patients receiving autografts preserved with 5 and 10% DMSO.
CONCLUSION: PBPC autografts can safely be stored for at least 5 years in 5% DMSO and used for ASCT.