Mizrachi Aviram, Hilly Ohad, Raveh Eyal, Attias Joseph, Nageris Ben I
Department of Otorhinolaryngology-Head and Neck Surgery, Rabin Medical Center, Beilinson Campus, Petach Tikva, and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
Department of Communication Sciences and Disorders, University of Haifa, Haifa, Israel.
JAMA Otolaryngol Head Neck Surg. 2015 Sep;141(9):840-4. doi: 10.1001/jamaoto.2015.1347.
Bilateral vestibular failure is a debilitating condition that may lead to oscillopia and adversely affect quality of life. Researchers have suggested that vestibular function might be restored with implantation of an external mechanical stimulation device. However, it is essential that such a device must not interfere with normal hearing.
To evaluate the effect of vestibular implant insertion on hearing in a sand rat model with normal hearing.
DESIGN, SETTING, AND SUBJECTS: The study was conducted in a tertiary medical center in accord with the guidelines of the Rabin Medical Center Animal Care and Use Committee. The experiment was performed in 6 adult, 6-month-old, fat sand rats (Psammomys obesus), which have a unique aural anatomy that permits access to the inner ear. The study dates were March 2013 to March 2014.
The sand rats were anesthetized and electrodes were implanted unilaterally (in 6 sand rats) or bilaterally (in 2 sand rats) in all 3 semicircular canals (lateral, then posterior, and then superior) by fenestration of the respective ampullas. To measure air and bone conduction thresholds, auditory nerve brainstem evoked responses to alternating polarity clicks and 1-kHz tone bursts were tested before surgery, at each operative stage, and after surgery.
Air or bone conduction threshold shifts after implantation of a vestibular implant electrode array in each semicircular canal.
After unilateral implantation of the vestibular implant, sand rats showed a sideways head tilt, whereas after bilateral implantation, sand rats ran around in circles and were unable to stand still or walk on a treadmill. On statistical analysis, statistically significant differences from preoperative values were obtained across all stages of surgery for air conduction thresholds. The largest and statistically significant air conduction shift for 1-kHz stimuli (mean [SD, 13.7 [2.8] dB; P < .004) as well as for clicks (12.5 [2.1] dB; P < .002) was found for the superior canal electrode insertion. For the posterior canal, the air conduction thresholds to 1-kHz stimuli and to clicks shifted significantly after electrode insertion (mean [SD], 7.5 [2.3] dB; P < .01 and 7.5 [0.9] dB; P < .001). For the lateral canal, only the threshold to clicks changed significantly (mean [SD], 5.5 [1.7] dB; P < .02). Bone conduction thresholds did not change significantly after vestibular electrode insertion.
Implantation of a vestibular device is associated with mild to moderate conductive hearing loss in fat sand rats with normal hearing, especially when the device is placed in the posterior and superior semicircular canals. Bilateral implantation is associated with major vestibular pathologic results. Further studies are needed in animals with cochlear or vestibular disorders before it can be definitively concluded that vestibular implantation carries only a minor risk to hearing.
双侧前庭功能衰竭是一种使人衰弱的病症，可能导致视振荡，并对生活质量产生不利影响。研究人员提出，通过植入外部机械刺激装置可能恢复前庭功能。然而，至关重要的是，这样的装置绝不能干扰正常听力。
评估在前庭功能正常的沙鼠模型中植入前庭植入物对听力的影响。
设计、地点和研究对象：该研究在一家三级医疗中心进行，符合拉宾医疗中心动物护理和使用委员会的指导方针。实验在6只6个月大的成年肥胖沙鼠（肥胖金仓鼠）身上进行，它们具有独特的耳部解剖结构，便于进入内耳。研究时间为2013年3月至2014年3月。
将沙鼠麻醉，通过分别打开各个壶腹的窗口，在所有3个半规管（外侧、后外侧和上半规管）单侧（6只沙鼠）或双侧（2只沙鼠）植入电极。为了测量气导和骨导阈值，在手术前、每个手术阶段和手术后测试听神经脑干对交替极性咔嗒声和1kHz短纯音的诱发反应。
在前庭植入电极阵列植入每个半规管后气导或骨导阈值的变化。
单侧植入前庭植入物后，沙鼠出现头部向一侧倾斜，而双侧植入后，沙鼠绕圈奔跑，无法静止站立或在跑步机上行走。经统计分析，在手术的所有阶段，气导阈值与术前值相比均有统计学显著差异。上半规管电极插入时，1kHz刺激（平均[标准差，13.7[2.8]dB；P<0.004）以及咔嗒声（12.5[2.1]dB；P<0.002）的气导变化最大且具有统计学显著性。对于后外侧半规管，电极插入后，1kHz刺激和咔嗒声的气导阈值显著变化（平均[标准差]，7.5[2.3]dB；P<0.01和7.5[0.9]dB；P<0.001）。对于外侧半规管，只有咔嗒声的阈值有显著变化（平均[标准差]，5.5[1.7]dB；P<0.02）。前庭电极插入后骨导阈值无显著变化。
在前庭功能正常的肥胖沙鼠中，植入前庭装置会导致轻度至中度传导性听力损失，尤其是当装置放置在后外侧和上半规管时。双侧植入与严重的前庭病理结果相关。在能够明确得出前庭植入对听力仅带来较小风险的结论之前，需要对患有耳蜗或前庭疾病的动物进行进一步研究。
