急性单侧耳鸣患者对侧白噪声刺激对畸变产物耳声发射的影响

Influence of contralateral white noise stimulation on distortion product otoacoustic emissions in patients with acute unilateral tinnitus

目的:了解急性单侧耳鸣患者耳蜗外毛细胞和内侧橄榄耳蜗系统的功能。方法:选择2003-2005年期间就诊中山大学附属第一医院的听力正常或轻度下降(4～8kHz之间每倍频程纯音听阈≤25dB)并伴有轻度感音神经性聋的单侧急性耳鸣患者28例(急性耳鸣组)。正常对照组为正常听力无耳鸣(125～8000Hz之间每倍频程听阈≤15dB)的20～22岁医科大学生14例。进行畸变产物耳声发射检测和健耳白噪声抑制后再次检测,并对耳鸣进行匹配。①以两个等强度(L1=L2=70dBSPL)初始纯音,f1和f2的几何均数f0为畸变产物耳声发射的反应频率,f2/f1=1.22,取频率谱中2f1-f2处的反应幅值,以反应幅值高于噪声底3dB以上并超过1倍标准差为引出畸变产物耳声发射,得出畸变产物耳声发射反应幅值听力图,共取0.5,1,2,4和8kHz等5个频率点进行测量。对侧抑制方法为在对侧耳给与70dBSPL的宽带白噪声掩蔽,正常组+白噪声为正常组对侧耳加70dHSPL的白噪声,急性耳鸣组+白噪声指急性耳鸣组对侧耳加白噪声,记录畸变产物耳声发射幅值。②采用对侧健耳进行耳鸣匹配,声信号为125～8000Hz的纯音、窄带噪声、白噪声和啭音,给予阈上10dBHL的纯音,从低频至高频以0.1个倍频程进行扫频以进行音调匹配,若不成功再采用窄带噪声进行匹配,或改用白噪声,然后再以2dB的步长调整响度,以能达到与耳鸣相似度80%以上才认为匹配成功,记录时取所给声信号的主频,响度为健耳感觉级(dBSL)。结果:两组患者均完成各项指标的测量,全部进入结果分析。①两组患者在0.5kHz、1kHz和8kHz3个频率点的白噪声抑制后畸变产物耳声发射幅值差异有显著性意义(P<0.05);正常对照组的对侧白噪声抑制后畸变产物耳声发射幅值下降,抑制后的幅值与未抑制时比较,差异有显著性意义(P<0.05);急性耳鸣组给与对侧白噪声抑制后畸变产物耳声发射幅值与未抑制时比较差异无显著性意义(P=0.645)。②急性耳鸣组28例(28耳)成功匹配24例(24耳,85.7%),其中窄带噪声匹配成功的有20例(83.3%),3例为纯音,主频分布为0.5～6kHz,响度5～20dBSL;1例为白噪声,响度为10dBSL。结论:急性耳鸣组的病例有中高频段的耳蜗损害;耳鸣患者可能有内侧橄榄耳蜗系统传出系统作用的下降或缺乏。

AIM： To comprehend the functions of cochlea out hair cells and medial olivocochlear system of acute unilateral tinnitus patients. METHODS： Totally 28 patients with acute unilateral tinnitus accompanying neurosensory deafness from the First Affiliated Hospital of Sun Yat-sen University between 2003 and 2005 were selected as acute tinnitus group, who had normal hearing or mild hearing loss [pure-tone average （PIA） ≤25 dB in every octave band among 4-8 kHz]. And 14-medical college students aged 20-22 years with normal hearing （PTA≤ 15 dB among 125-8 000 Hz） were control group. The amplitudes of distortion product otoacoustic emissions （DPOAE） were detected, and then retested after contralateral suppression of white noise. The tone and loudness of tinnitus were also matched at the same time. ①Using 2 primary pure tones f1 and f2 which were equal and set at 70 dB SPL and the ratio of f2/f1=1.22, the geometric mean f0 of f1 and f2 was the reactive frequency. The DPOAE-grams were measured at 0.5,1,2,4 and 8 kHz frequencies when signal-to noise ratio （S/N） of reactive amplitudes were higher than 3 dB and exceeded 1 standard deviation. The 70 dB SPL white noise masking was used to give the contralateral suppression to lateral ear in both groups. Then the amplhudes of DPOAE-grams were compared between two groups.②Tinnitus match were measured among contralateral normal ears. The sounds were selected as pure tone, narrow band noise range 125-8 000 Hz, white noise and warble. Pitch-matching was performed using frequencysweep range at 0.1 octave band, and the intensity was 10 dBHL excess PTA threshold. The sound of pitch-matching was tone firstly, then narrow band noise or white noise respectively. Then 2 dB step was selected to adjust loudness. It was a successful match when patients thought there was more than 80% resemblance with their tinnitus. The loudness of tinnitus is expressed as the sensation level （dBSL） of contralateral normal ear, with the record of the main frequency of delivered sounds. RESULTS： All the patients accomplished the markers detections and entered into the result analysis.①There were significant differences in the amplitudes of DPOAE at 0.5 kHz, 1 kHz and 8 kHz frequencies between beth groups （P 〈 0.05）. The amplitudes in control group decreased after contralateral suppression of white noise, and the differences had statistics significance （P 〈 0.05）. There was no significant change in the amplitudes of DPOAE after contralateral suppression in acute tinnitus group （P=0.645）;②Twenty-four ears （85.7%） were successful matched among 28 cases of acute tinnitus group, including 20 cases （83.3%） of narrow band noise and 3 cases of pure tone. The main frequencies distributed from 0.5-6 kHz and the intensities range from 5-20 dBSL. Only one case was white noise with intensity of 10 dBSL. CONCLUISION： There is cochlear impairment in the OHC of the middle-high frequencies and the medial olivocochlear system of the patients with acute unilateral tinnitus.