Songer Jocelyn E, Rosowski John J
Eaton-Peabody Laboratory of Auditory Physiology, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, USA.
Hear Res. 2005 Dec;210(1-2):53-62. doi: 10.1016/j.heares.2005.07.003. Epub 2005 Sep 8.
A superior semicircular canal dehiscence (SCD) is a break or hole in the bony wall of the superior semicircular canal. Patients with SCD syndrome present with a variety of symptoms: some with vestibular symptoms, others with auditory symptoms (including low-frequency conductive hearing loss) and yet others with both. We are interested in whether or not mechanically altering the superior canal by introducing a dehiscence is sufficient to cause the low-frequency conductive hearing loss associated with SCD syndrome. We evaluated the effect of a surgically introduced dehiscence on auditory responses to air-conducted (AC) stimuli in 11 chinchilla ears. Cochlear potential (CP) was recorded at the round-window before and after a dehiscence was introduced. In each ear, a decrease in CP in response to low frequency (<2 kHz) sound stimuli was observed after the introduction of the dehiscence. The dehiscence was then patched with cyanoacrylate glue leading to a reversal of the dehiscence-induced changes in CP. The reversible decrease in auditory sensitivity observed in chinchilla is consistent with the elevated AC thresholds observed in patients with SCD. According to the 'third-window' hypothesis the SCD shunts sound-induced stapes velocity away from the cochlea, resulting in decreased auditory sensitivity to AC sounds. The data collected in this study are consistent with predictions of this hypothesis.
上半规管裂（SCD）是上半规管骨壁的破裂或孔洞。患有SCD综合征的患者会出现多种症状：一些有前庭症状，另一些有听觉症状（包括低频传导性听力损失），还有一些两者都有。我们感兴趣的是，通过制造裂孔对上半规管进行机械改变是否足以导致与SCD综合征相关的低频传导性听力损失。我们评估了手术制造的裂孔对11只龙猫耳朵气导（AC）刺激听觉反应的影响。在制造裂孔前后，在圆窗记录耳蜗电位（CP）。在每只耳朵中，制造裂孔后观察到对低频（<2 kHz）声音刺激的CP下降。然后用氰基丙烯酸酯胶修补裂孔，导致裂孔引起的CP变化逆转。在龙猫中观察到的听觉敏感性可逆下降与SCD患者中观察到的AC阈值升高一致。根据“第三窗”假说，SCD将声音诱发的镫骨速度从耳蜗分流，导致对AC声音的听觉敏感性降低。本研究收集的数据与该假说的预测一致。
