Objective assessment of auditory thresholds in noise‐induced hearing loss using steady‐state evoked potentials

Objective assessment of auditory thresholds in noise‐induced hearing loss using steady‐state evoked potentials The purpose of this study is to evaluate whether steady‐state evoked potential (SSEP) can be used for objective estimation of auditory thresholds in patients with noise‐induced hearing loss (NIHL). Eleven subjects (22 ears) with a characteristic audiometric notch between 3000 and 6000 Hz participated in this study. Both pure‐tone thresholds and SSEP thresholds were obtained for each ear of all subjects. The correlation of SSEP thresholds and pure‐tone thresholds was assessed. The results show that SSEP thresholds predicted pure‐tone thresholds with correlation coefficients (r) of 0.86, 0.92, 0.94 and 0.95 at 500, 1000, 2000 and 4000 Hz respectively. Typically, the SSEP thresholds overestimate the pure‐tone thresholds by 10–20 dB, but they closely reflect the configuration of the audiogram. The strength of the relationship between SSEP and pure‐tone thresholds increased with increasing frequency and increasing degree of hearing loss. In conclusion, SSEP can be used as a reliable and objective tool to assess auditory thresholds in patients with noise‐induced hearing loss with high‐frequency dips.     

Otological trauma resulting from the Soho Nail Bomb in London,April 1999

Otological trauma resulting from the Soho Nail Bomb in London, April 1999 We report the otological effects of the April 1999 Soho Nail Bomb on 17 patients. Twenty‐one (62%) tympanic membranes were perforated (pars tensa only); 78% closed spontaneously within 6 months. The mean size of the perforation in the tympanic membrane nearer to the blast was significantly larger than the opposite side [33% ± 8.3 (mean ± SD) and 13% ± 4.1 respectively; P = 0.02]. All patients reported hearing losses that were mixed conductive and sensorineural but mainly high‐frequency sensorineural (4, 6 and 8 kHz, pure tone average 42.3 dB ± 20.5). The sensorineural hearing loss correlated inversely with the distance from the explosion but not with the size of perforation. There was no significant difference in the hearing loss between the ear facing the blast and the opposite ear. Fifteen patients (88%) had temporary tinnitus. No patient complained of any vestibular symptoms. The otological effects of a nail bomb in an enclosed space have not been previously reported. Furthermore, an inverse correlation between hearing loss and distance from the explosion and a significant difference in perforation size facing the blast, compared with the opposite side, are also presented for the first time. The high spontaneous closure rate of perforations and minimal ongoing disability from sensorineural losses favour conservative management in most cases.     

The effect of combined spinal‐epidural (CSE) anaesthesia and size of spinal needle on postoperative hearing loss after elective caesarean section

The effect of combined spinal epidural (CSE) anaesthesia and size of spinal needle on postoperative hearing loss after elective caesarean section The exact aetiology of vestibulocochlear dysfunction after spinal anaesthesia is unknown. Low‐frequency hearing loss occurs after spinal anaesthesia. The aim of this study was to investigate the effects of combined spinal–epidural (CSE) anaesthesia and size of spinal needle on vestibulocochlear dysfunction, using pure tone audiometry performed pre‐ and on the first and the second day postoperatively. Forty‐five patients who were to undergo elective caesarean section were evaluated. In group I, CSE anaesthesia (18 G Tuohy, 25 G Whitacre pencil‐point‐design spinal needles) was performed in 15 patients. In group II, spinal anaesthesia was performed in 15 patients with 25 G Whitacre pencil‐point‐design spinal needles and, in group III, spinal anaesthesia was performed in 15 patients with 22 G Whitacre pencil‐point‐design spinal needles. In the pre‐ and on the first and the second day postoperatively, the pure tone audiogram was performed in the audiology laboratory of our hospital, using a calibrated Kamplex Diagnostic Audiometer AC 40 in a noise‐free room. When the CSE anaesthesia group and 22 G spinal group were compared for change in hearing between the pre‐ and postoperative periods, a statistically significant difference was observed at R‐right ear 125 Hz (P < 0.025) and at L‐left ear 125 Hz (P < 0.023), and at L‐left ear 1000 Hz (P < 0.036) and at R‐right ear 1500 Hz (P < 0.006), and at L‐left ear 1500 Hz (P < 0.022). At other frequencies, the difference was insignificant. When the CSE anaesthesia group and 25 G spinal group were compared for change in hearing between the pre‐ and postoperative periods, no statistically significant difference was detected at any frequency tested. When 22 G spinal group and 25 G spinal group were compared for change in hearing between the pre‐ and postoperative periods, there was some hearing loss at low frequency, although this difference did not reach statistical significance. The positive correlation of low‐frequency hearing loss and increased pressure in the epidural space (which decrease the risk of cerebrospinal fluid leakage through the dura) suggests that cerebrospinal fluid leakage via the spinal puncture hole is not the only factor involved. Perioperative fluid replacement alone may not prevent hearing loss but CSF loss through the dural puncture site should also be prevented.     

Should patients with asymmetrical noise‐induced hearing loss be screened for vestibular schwannomas?

Should patients with asymmetrical noise‐induced hearing loss be screened for vestibular schwannomas? The Peterborough ENT department receives many referrals for MoD personnel who have suffered hearing loss from occupational noise exposure. Those patients with asymmetrical sensorineural hearing loss are routinely screened for vestibular schwannomas by MRI scanning. Scan reports from the past 5 years have been reviewed and out of 152 scans, four revealed vestibular schwannomas giving a pick‐up rate of 2.5%, which compares favourably with other published pick‐up rates. Review of the audiograms in these cases suggests that they can be misleading in this context. The conclusion is that patients with noise‐induced asymmetrical hearing loss should be screened for acoustic neuromas.     

胰腺癌的临床表现

胰腺的临床表现因病变而异。腹痛、黄疸及体重减轻是胰腺癌的主要临床表现。部分病人同时可表现为发热、焦虑、抑郁、胆囊肿大及血栓性静脉炎等。     

Development of fluridil,a topical suppressor of the androgen receptor in androgenetic alopecia

Nonsteroidal antiandrogens (AA) cannot be topically used for androgenetic alopecia (AGA) because of systemic resorption. A new class of androgen receptor (AR) suppressors designed for safe topical treatment of AGA was synthesized from (3‐amino‐2‐hydroxy‐2‐methyl‐N‐(4‐nitro‐3‐trifluoromethyl)phenyl) propanamide (BP‐34), to contain perfluoroalkyl moieties. The trifluoromethyl derivative (fluridil) at 10 μM decreased expression of the AR in LNCaP human cells by 95%, its serum half‐life was 6 h; it decomposes hydrolytically to BP‐34 and trifluoroacetic acid. Acute intraperitoneal maximum tolerated dose (MTD) of fluridil in mice is 270–300 mg/kg/d and the subacute MTD is 450 mg/kg/d. The oral LD₅₀ in mice was 2,872 mg/kg in males, 2,232 mg/kg in females, and >2,500 mg/kg in rats. Fluridil solution in isopropanol was not cutaneously absorbed in rabbits, did not sensitize or show any phototoxic or photoallergic effects on guinea pig skin, and demonstrated no skin irritation potential in rabbits and humans. Fluridil solid induced only slight and reversible eye irritancy in rabbits and displayed no cytotoxicity to rabbit corneal fibroblasts in vitro. Fluridil demonstrated no significant mutagenicity potential by Ames method. In a double‐blind study, 43 males with AGA, Norwood grade II to Va, used topical 2% fluridil in isopropanol or the vehicle daily for 12 months. Anagens (growing hairs) increased in the fluridil group from 76% to 89%. All hematological and biochemistry values remained within normal range, including testosterone, which varied but seasonally. No fluridil or its decomposition product (BP‐34) was detected in serum. No adverse side effects were reported. Drug Dev. Res. 59:292–306, 2003. © 2003 Wiley‐Liss, Inc.     

条件声暴露后豚鼠耳埚外毛细胞F-激动蛋白的表达（英）

It has been found that in many mammalian animals,including mankind, non-traumatic"conditioning"noiseexposures can make the inner ear more resistant to trau-matic noise exposure. The possible mechanism underlyingthis phenomenon which is now known as"toughening",has been extensively studied . All the explanations aboutthis mechanism, however, have not been acceptable. Asa primary component of the structural filaments of the haircells and some supporting cells, filamentous actin (F-actin) are believed to be the basic unit in hair cell reac-tion. Furthermore, recent studies have shown that F-actinis involved in actin-mediated motile processes of the outerhair cells. Thus, F-actin may play an important role inthe process of"toughening". The present study is ①toobtain more information on the distribution of F-actin inthe guinea pig cochlea, ②to observe the effects of condi-tioning noise exposure on the expression of F-actin, and③to determine the relationship between the changes of F-actin expression in the outer hair cells (OHC) and the"toughening" phenomenon.     

突发性聋与铁代谢障碍疾病关系的临床调查

对１９７９年７月至１９９６年６月的突发性聋发病情况进行前瞻性研究与回顾性分析，探讨突聋与铁代谢障碍疾病的关系，前瞻性研究的对象分为铁代谢障碍疾病组２１８例，血液病组２１５例和正常对照组４８５０例；回顾性分析为１７年间资料完整的４２９例突聋患者史的代谢障碍疾病及其他血液病的发病情况。结果表明，铁代谢障碍疾病组的突聋调整年发病率显著高于血液病组以及正常对照组，４２９例突聋患者的无贫血缺铁，缺铁性人同血     

Electron microscopic localization of nitric oxide I synthase in the organ of Corti of the guinea pig

Nitric oxide synthase (NOS) activity has been detected previously in the mammalian cochlea at a light microscopic level. Here we present results of electron microscopic analysis for post-embedding immunoreactivity of neural-type NOS I in the cochlea of the guinea pig. Strong enzyme immunoreactivity was identified in the cytoplasm of inner and outer hair cells. Gold-labeled NOS I antibodies were mainly located in electron-dense areas of the cytoplasm, whereas electron-lucent regions of the receptor cells were nearly free from any immunoreactivity. In both types of hair cells anti-NOS I antibodies were also visible in the cuticular plates, hair bundles and nuclei. Further ultrastructural analysis revealed that the submembranous cisternae of the outer hair cells were nearly free from any reaction product, demonstrating that the whole cytoplasm of this hair cell was not immunoreactive. Other NOS I immunoreactivity was identified in the cuticular plates of the inner and outer pillar cells and in the cytoskeletal elements located in the apical parts of Deiter cells, forming the lamina reticularis or in cytoskeletal-containing regions in basal Deiter cells. Anti-NOS antibodies were visible in the nuclei of various cell types. Our findings suggest that nitric oxide produced by NO I synthase in the organ of Corti may act as a modulator of hair cell physiology during the processes of signal transduction with frequence selectivity.