THE function and morphology study of eustachian tube based on sonotubometry and multi-slice spiral CT in normal subjects / 中华耳鼻咽喉头颈外科杂志

Objective: In order to assess ET more comprehensively, sonotubometry (STM)combined with CT images were applied to investigate the opening features of eustachian tube (ET) in normal subjects. STM was also used as a monitor training ET opening maneuver and optimizing CT scan parameters. Methods: Following ET opening training monitored by STM, STM data of ET opening duration and maximum sound pressure from 13 healthy volunteers (10 males and 3 females, 22 to 26 years old) were acquired using maneuvers of swallowing and Valsalva in standing and supine positions. Two trials of CT scan, setting A (slice thickness 6.0 mm, manually simulated to 0.6 mm, reconstruction thickness 0.6 mm) for normal and Valsalva scans and setting B(slice thickness 0.4 mm,reconstruction thickness 0.4 mm)for Valsalva scan, were conducted in each subject. The bone area and cartilage area of ET were measured respectively in reconstructed CT images. Statistical software SPSS 19.0 was employed in data analysis. Results: The duration of ET opening and maximum sound pressure by Valsalva were longer and stronger than those by swallowing in both positions. For Valsalva maneuver, standing position resulted in longer ET opening duration compared to supine position (P<0.05). Under setting A, ET cartilage area was measured larger by Valsalva scan than by normal scan (P<0.05). By Valsalva scan, setting A captured larger ET cartilage area compared to setting B (P<0.05). CT setting B resulted in longer scan time in comparison to setting A (P<0.05). Conclusions: Techniques of STM in supine position plus CT scan under setting A can be combined by Valsalva passive ET opening. Not only the invisible ET lumen through routine CT scan can be illustrated, but also relevant ET open-close process is shown, therefore, this study provides the technique for ET research of function and structure.

Inner ear morphological study of guinea pigs with acoustically evoked short latency negative response / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To establish a model of ototoxicity in guinea pigs with acoustically evoked short latency negative response (ASNR) and verify the responsible organ of ASNR based on microscopic characteristics of basal membranes, saccules, utricles and ampulla canalis semicircularis of the inner ear.</p><p><b>METHODS</b>Total of 45 guinea pigs were employed in the experiment, which were randomly divided into the control group (15 subjects, 30 ears) and the deafened group (30 subjects, 60 ears). Each animal experienced auditory brainstem response (ABR). A quick treatment was employed for deafened group consisting of a subcutaneous injection of kanamycin at a dose of 400 mg/kg followed by jugular vein injection of ethacrynic acid at a dose of 40 mg/kg one hour later. The animals were performed ABR test from 7 to 10 days after the drug administration. The deafened group was further divided into ASNR group and non-ASNR group based on the presence of ASNR. All the guinea pigs were sacrificed after ABR tests. The Corti organ, macula sacculi, macula utriculi and crista ampullaris were observed by light microscope.</p><p><b>RESULTS</b>In the deafened group (60 ears), 3 subjects died postoperatively, 27 subjects (54 ears) provided full data. ASNR was elicited in 19 ears (35.2%, 19/54), the thresholds of ASNR were from 110 to 125 dBSPL with average of (121.7 ± 4.5) dBSPL. ASNR latency ranges were 1.80 - 2.08 ms, the average latency of thresholds were (1.93 ± 0.07) ms. The stretched preparation results: overall hair-cell density of macula saccule, macula utriculi and crista ampullaris decreased in order of normal control group, ASNR group and non-ASNR group. There was no difference between the normal group and ASNR group for cell density of macula saccule. Apart from this, statistical differences were found among other groups.</p><p><b>CONCLUSIONS</b>The present study evoked ASNR in an ototoxicity guinea pig model which was profound hearing loss with normal saccular function and normal saccular hair cell density. It suggested that ASNR originates from the saccule and have no relation with cochlear, utricle and semicircular canal according to morphological study.</p>

Origin of acoustically evoked short latency negative response in guinea pigs / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To establish a model of acoustically evoked short latency negative response (ASNR) in guinea pigs, a model of profound hearing loss with normal saccular functions, and verify the correlation between ASNR and vestibular evoked myogenic potential (VEMP).</p><p><b>METHODS</b>Thirty-two healthy guinea pigs were employed in the experiment, which were randomly divided into control group (16 subjects) and deafened group (16 subjects). Each animal experienced auditory and vestibular tests including auditory brainstem response (ABR), VEMP and caloric test. A quick treatment was employed for deafened group consisting of a subcutaneous injection of kanamycin at a dose of 400 mg/kg followed by a jugular vein injection of ethacrynic acid at a dose of 40 mg/kg one hour later. The animals were received ABR, VEMP and caloric test 7 - 10 days following the drug administration. The deafened group was further divided into ASNR group and non-ASNR group, based on the presence of ASNR.</p><p><b>RESULTS</b>In deafened group, five subjects died postoperatively, 11 subjects (22 ears) provided full data, ASNR was elicited in eight ears (36.4%), the threshold was 120 - 130 dB SPL with mean of (124.4 ± 4.96) dB SPL. Its latency range was 1.75 - 2.60 ms with mean of (2.15 ± 0.27) ms. The mean latency of threshold was (2.34 ± 0.18) ms. All eight ASNR ears presented with VEMP. The VEMP threshold, positive and negative potential latencies proved no statistical difference (P > 0.05) between ASNR group and control group. Significant difference was detected between the VEMP presence of ASNR group and non-ASNR group (P = 0.002). There was no statistically significant correlation between VEMP and caloric test neither between ASNR and caloric test in deafened group.</p><p><b>CONCLUSIONS</b>This study evoked ASNR in an ototoxicity guinea pig model which has profound hearing loss with normal saccular functions. The presence of ASNR correlated with VEMP, however, not correlated with caloric test, suggesting that ASNR and VEMP are both originated from the saccule.</p>