桥小脑角占位性病变的临床听力学表现

Audiological features of cerebellopontine angle (CPA) tumors

本文总结了经CT或MRI证实以及部分经手术证实的101例桥小脑角占位性病变的纯音测听，听性脑干反应（ABR），耳蜗电图（ECochG）以及前庭功能的表现。结果显示：ABR多表现为Ⅰ～Ⅴ间或延长（＞45ms），仅Ⅰ波存在或ABR各波均消失。未见波Ⅴ幅度小于波Ⅰ。当肿物较大时，可见时测ABR异常。极重度聋患者（35．5％），仍可引出异常ABR波形，故仍不可忽视ABR检查；听力轻度下降，甚至正常考ABR仍有改变。AP出现率随肿物增大而降低，－SP／AP比值≥0．4，可能是继发性伤及耳蜗所致。5例ABR表现正常者仍有半规管功能低下。提示前庭功能检查对桥小脑均占位性病变的诊断具有一定参考意义，临床应将ECochG和前庭功能检测列为诊断桥小脑角占位性病变的参考指标。

Electrocochlegraphy (ECochG), auditory brainstem response, pure tone audiometry and electronystagmusgraphy (ENG) were recorded on 101 patients with CPA tumorsproved by CT, MRI or surgery. The results showed that most of the patients had prolonged ABR I ~ V intervals (>4. 5ms), only wave I appeared or ABR wave formsdisappeared. When CPA tumor became larger, it could cause abnormal ABR on the opposite side. The incidence of AP in ECochG was decreased as the tumorsize increased.The -SP/AP ratio ≥0. 4 might indicate that the cochlea was damaged. In patients withprofound hearing loss (35. 5%), abnormal ABR could also be found. So in these patients the ABR test was necessary. In patients with less hearing loss or even normalhearing the ABR could also be abnormal. Five of 101 patients had normal ABR, but abnormal semicircular canal function. This result suggested that vestibular test was helpful for the diagnosis of CPA tumors.