应用多频稳态诱发电位鉴别诊断职业性噪声聋的临床研究

目的探讨应用多频稳态诱发电位（multiple auditory steady-state evoked responses，ASSR）鉴别诊断职业性噪声聋的方法与意义。方法33例客观聋组、47例夸大聋组和30例正常听力组人员均行0．5、1、2、4kHz频率处的ASSR和纯音测试（pure tone threshold audiometry，PTA），对结果进行统计学分析。结果①客观聋组、正常听力组的ASSR反应阈与PTA听阈相关系数为0．67～0．89，夸大聋组为0．28～0．47。②在Bayes准则下分别应用ASSR反应阈、PTA听阈进行判断分析的总体符合率分别为78．18％、82．73％，判别夸大聋的准确率为65．96％、74．47％。③客观聋组的ASSR反应阈与VIA听阈存在线性依存关系，可建立回归方程。结论在职业性噪声聋诊断中，可利用ASSR为鉴别夸大聋和评估真实听阈提供证据。     

A regional experience of red cell aplasia

The incidence and current management of red cell aplasia in children was determined from a retrospective survey of haematologists and paediatricians in the northern health region of England over a 7-year period. Thirty-three children were diagnosed: 4 had Diamond Blacktan anaemia, 22 transient erythroblastopenia of childhood, and 7 parvovirus B19 aplasia, with annual incidences of 1, 5 and 2 per 1,000,000 children respectively. Many were over-investigated. Three with Diamond Blackfan anaemia were steroid responsive. One with transient erythroblastopenia was retrospectively diagnosed because anaemia did not recur after steroids were stopped. Transient erythroblastopenia is the most common single cause of red cell aplasia in immunocompetent children. Time, observation and bone marrow examination before steroid therapy are the ways to distinguish transient erythroblastopenia from Diamond Blackfan anaemia or leukaemia. Interpretation of red cell indices using age-related percentiles may reduce the number of inappropriate investigations of the anaemia, but is often unhelpful in distinguishing the various causes of red cell aplasia.     

对用镫骨肌声反射推算听敏度的评估

听力损失的法医学鉴定，须采用客观、准确、定量的听力测验方法。镫骨肌声反射具有客观、所需设备简单、操作技术方便、快捷、检查费用低廉等优点。国外学者对此进行了较多研究，但结果差异较大，国内这方面研究甚少。本文按严格纳入标准，选择大样本运用逐步多元回归统计分析，建立了推算PTA的数学模型，经统计学显著性检验，新建方程具有较高准确性，且可信度均较过去推算方法为好，可作为纯医学鉴定中客观评定听力下降程度的常规筛选方法。     

Ion channels and the control of blood pressure

Ion channels exist in all cells and are enormously varied in structure, function and regulation. Some progress has been made in understanding the role that ion channels play in the control of blood pressure, but the discipline is still in its infancy. Ion channels provide many different targets for intervention in disorders of blood pressure and exciting advances have been made in this field. It is possible that new drugs, as well as antisense nucleotide technology or gene therapy directed towards ion channels, may form a new class of treatments for high and low blood pressure in the future.     

Otoacoustic emissions--an approach for monitoring aminoglycoside induced ototoxicity in children

Objectives: the early detection of hearing impairment caused by ototoxic drugs, such as aminoglycosides, has been the aim of research world-wide. Histopathological studies have shown that the outer hair cells are the most susceptible cochlear components to injury from ototoxic drugs like aminoglycosides. Otoacoustic emissions reflect the functional status of the outer hair cells and constitute the only non-invasive means of objective cochlear investigation. The aim of this study was to evaluate the potential of otoacoustic emissions in early identification of aminoglycoside-induced cochlear dysfunction. In addition, a comparison with pure-tone audiometry or auditory brainstem responses was performed in order to determine if this test might provide a more reliable method of monitoring early ototoxic insults to the cochlea. Methods: twenty four children receiving gentamicin (4 mg/kg once daily) for 6–29 days were included in the study. Eleven children received gentamicin for up to 7 days (group A), while 13 underwent longer-term therapy lasting 8–29 days (group B). Hearing was serially monitored using transient evoked otoacoustic emissions and pure-tone audiometry (0.25–12 kHz) or auditory brainstem responses for younger or uncooperative children. Transient evoked otoacoustic emissions data were analysed in terms of emission amplitude and response reproducibility as a function of frequency. Results: all patients yielded a normal baseline audiometric assessment upon hospital admission. For group A patients no significant changes in hearing levels were observed either by pure-tone audiometry (P=0.2), auditory brainstem responses (P=0.3) or transient evoked otoacoustic emissions (mean response: P=0.06, reproducibility by frequency: P>0.05). For group B patients no significant changes in hearing levels measured by pure-tone audiometry (P=0.1) or auditory brainstem responses (P=0.4) were observed. Transient evoked otoacoustic emissions however revealed a statistically significant decrease in the mean response level (P=0.017) and in the reproducibility over the whole frequency spectrum (l kHz: P=0.0057, 2 kHz: P=0.0247, 3 kHz: P=0.0134, 4 kHz: P=0.0049, 5 kHz: P=0.0019). Conclusions: the findings suggest that transient evoked otoacoustic emissions are an extremely sensitive measure of the early effects of aminoglycoside-induced injury to the peripheral auditory system. Therefore, their use is recommended for regular monitoring of cochlear function, in the presence of potentially toxic factors, aiming at prevention of permanent damage.     

A case of non-metastatic giant mucinous carcinoma of the breast

A surgically resected case of giant mucinous carcinoma of the breast that had remained untreated for 2 years is reported. A 64-year-old postmenopausal woman presented with a large right breast mass (17.4 x 16.5 x 14.5 cm). Although she had noticed a mass in the right breast 2 years previously, she had not sought treatment. Mucinous carcinoma was diagnosed by core needle biopsy and she underwent right modified radical mastectomy with a free skin graft. There were no lymph node metastases or distant metastases. Fourteen months postoperatively, she remains well without evidence of tumor recurrence. Although several reports have suggested that pure mucinous carcinoma of the breast has a favorable prognosis, we need to follow this case until the clinical behavior and the outcome become clear.     

Factors affecting psychophysical tuning curves for hearing-impaired subjects with high-frequency dead regions

A dead region (DR) is a region of the cochlea where there are no functioning inner hair cells and/or neurons. DRs can be detected using the threshold-equalizing-noise (TEN) test, but psychophysical tuning curves (PTCs) are sometimes used to give a more precise estimate of the edge frequency of a DR; a shifted tip of the PTC indicates a DR. We show here that the shapes of PTCs for hearing-impaired subjects can be influenced by the detection of beats and simple difference tones (SDTs). As a result, PTCs can have tips at f_s, even when f_s falls in a DR. PTCs were measured for subjects with mild to moderate low-frequency and severe high-frequency hearing loss using sinusoidal and narrowband noise maskers (80-, 160-, 320-Hz wide): (1) in quiet; (2) in the presence of additional lowpass filtered noise (LF noise) designed to mask SDTs; (3) in the presence of a pair of low-frequency tones designed to interfere with the detection of beats (MDI tones). In condition (1), the PTCs were often W-shaped, with a sharp tip at f_s. This occurred less for the wider noise bandwidths. For subjects with good low-frequency hearing, the LF noise often reduced or eliminated the tip at f_s, suggesting that this tip was partly caused by detection of SDTs. For the sinusoidal and 80-Hz wide noise maskers, the addition of the MDI tones reduced the masker level required for threshold for masker frequencies adjacent to f_s, for nearly all subjects, suggesting a strong influence of beat detection. To minimize the influence of beats, we recommend using noise maskers with a bandwidth of 160 or (preferably) 320 Hz. In cases of near-normal hearing at low frequencies, we recommend using an additional LF noise to mask SDTs.     

Longitudinal relations between child vagal tone and parenting behavior: 2 to 4 years

The longitudinal relations between physiological markers of child emotion regulation and maternal parenting practices were examined from 2 to 4 years of age. At Time 1, cardiac vagal tone was assessed for one hundred four 2-year-olds (54 females); their mothers completed an assessment of parenting styles. Two years later, at Time 2, 84 of the original participants were reassessed on measures of cardiac vagal tone and parenting style. Results indicated both baseline cardiac vagal tone and maternal parenting practices to be stable from 2 to 4 years of age. Children's cardiac vagal tone predicted specific parenting practices from the toddler to preschool years. Further, child cardiac vagal tone moderated maternal restrictive-parenting practices from 2 to 4 years of age; mothers of children who were highly or moderately physiologically dysregulated were more likely to report restrictive parenting practices at both 2 and 4 years of age.     

Incorrect instruction in the use of the Valsalva manoeuvre for paroxysmal supra-ventricular tachycardia is common

Objective: Success rates for the Valsalva manoeuvre (VM) in treatment of paroxysmal supraventricular tachycardia (SVT) vary with performance technique. This study aimed to assess whether ED doctors instruct their patients to perform the recommended VM technique (supine position for 15 s). Methods: A multicentre, observational study of 35 ED registrars and 17 emergency physicians. Each doctor was asked to describe how he/she would instruct a patient in SVT to perform the VM. Results: Only five (9.6%) doctors would position their patient correctly and 31 (59.6%) would incorrectly instruct their patient to assume a sitting or semirecumbent position. Only five (9.6%) doctors would give specific instructions to blow for at least 15 s and 34 (65.4%) would instruct their patient to blow ‘as long as you can’. Only four (7.4%) doctors would use a sphygmomanometer to measure intrathoracic pressure during the VM. There were no significant differences (P > 0.05) between the registrar and physician group responses for any study endpoint. Conclusion: Few ED doctors correctly instruct their patients in the VM technique recommended for management of SVT. Hence, maximal vagal tone and SVT conversion rates may not be achieved in many cases. The use of the recommended VM technique is encouraged.     

Human auditory cortical dynamics during perception of long acoustic sequences: phase tracking of carrier frequency by the auditory steady-state response

We recorded human auditory cortical activity during the perception of long, changing acoustic signals and analyzed information provided by dynamic neural population measures over a large range of time intervals (approximately 24 ms-5 s). Participants listened to musical scales that were amplitude modulated at a rate of 41.5 Hz, generating an ongoing, stimulus-related oscillatory brain signal, the auditory steady-state response (aSSR). The aSSR generated energy at the amplitude modulation rate that was recorded using magnetoencephalography. As in previous work, the timing (phase) of this response varied with stimulus carrier frequency over the entire course of minute-long tone sequences ('phase tracking' of carrier frequency). The length of the time interval over which phase was calculated was systematically varied; significant phase tracking was regularly observed at analysis intervals of <50 ms in length. The right auditory cortex exhibited better phase tracking performance than the left at analysis intervals of 24-240 ms, and frequency dependent phase delays were consistently larger than those predicted by cochlear mechanics. Based on these empirical data, a model of the neural populations responsible for phase tracking suggests that it is produced by a subpopulation ( approximately 25%) of the cells generating the aSSR.