前庭诱发肌源性电位结合纯音测听在大前庭水管综合征患者的临床应用

目的 通过记录、分析大前庭水管综合征（LVAS）患者的前庭诱发的肌源性电位(VEMP) 和纯音测听（PTA）状况,了解其球囊及前庭下神经功能和纯音听力特征，探讨其在LVAS患者的临床应用及意义。方法 对22例（42耳）LVAS患者行内耳高分辨率CT扫描、纯音测听和VEMP检查,对检查结果结合其临床症状进行总结、分析。结果 双侧短声刺激42患耳中25耳（占59.5%）VEMP表现为高振幅和（或）低阈值；42患耳纯音测听有30耳（占71.4%）表现为低中频（2KHz以下）存在明显气骨导差的混合性聋。VEMP低阈值组，前庭水管内径平均值为（4.30±0.53）mm，纯音听力低中频平均气骨导差值为（36±17）dB HL， 19耳主观听力易受外界原因或发热致颅内压改变而波动；VEMP非低阈值组前庭水管内径平均值为（2.80±0.67）mm，纯音听力低中频平均气骨导差值为（32±15）dB HL，4耳主观听力易受外界原因或发热致颅内压改变而波动。结论 VEMP阈值较低者，其前庭水管平均内径值较大，主观听力也易受外界原因或发热致颅内压增高的改变而波动。而纯音听力损失程度与前庭水管内径平均值无相关性，与VEMP振幅的大小及阈值的高低亦无相关性。

Clinical application of VEMP combined with PTA in LVAS' patients

Objective Recording and analyzing vestibular evoked myogenic potentials (VEMP) and pure tone audiometry(PTA) in large vestibular aqueduct syndrome(LVAS), may reveal the function of the saccule and vestibular nerve, describe the characteristics of PTA, and investigate its clinical application and significance in LVAS. Methods The results of the examination and clinical symptoms of 22 cases of LVAS (42 affected ears) who were all underwent high resolution CT scan of inner ear, PTA and VEMP were summarized and analyzed. Results 25 of 42(59.5%) affected ears which were excited by VEMP with bilateral short sound stimulation showed a high amplitude and/or low threshold. 30 of 42(71.4%) affected ears excited by PTA showed mixed hearing loss with the feature of significant air-bone gap in low and intermediate frequency (below 2KHz). In the low-threshold group of VEMP, the mean value of the vestibular aqueduct was (4.30±0.53) mm, and the pure tone average of the air-bone gap in low frequency was (36±17) dB HL. 19 ears were easily influenced by external factors or fluctuations of internal cranial pressure caused by fever. In the non-low threshold group of VEMP, the mean value of vestibular aqueduct was (2.80±0.67) mm, and the pure tone average of the air-bone gap in low frequency was (32±15) dB HL. 4 ears were easily influenced by external factors or the fluctuations of internal cranial pressure caused by fever. Conclusions The average value of vestibular aqueduct diameter is larger in patients with a lower VEMP threshold whose subjective hearing are affected by the external factors orthe fluctuations of internal cranial pressure caused by fever. But there is no correlation between the degree of the hearing loss with the mean value of vestibular aqueduct, nor with the characteristics of VEMP.