Probe Into The Diagnostic Value Of OAE During The Glycerol Test In The Early Endolymphatic Hydrops

Objective: Meniere's disease is characterized by recurrent, spontaneous episodic vertigo with tinnitus and hearing loss; Its pathologic feature is the endolymphtic hydrops. But for the patients of the probable Meniere's disease without hearing loss, the routine pure tone audiometry (PTA) can not show the change of the cochlear function with the early endolymphatic hydrops. Otoacoustic emission(OAE) is a more sensitive method, which can describe the cochlear function with or even without hearing loss. The motive of this investigation is to use OAE combined with the glycerol test to find this change.Method: We chosed single or double ears (40 ears) of the patients of the probable Meniere's disease as the doubtful group and the control group consisted of 17 normal volunteers (34 ears). Following external and middle ear assessments and PTA, OAE were recorded before and 1 hour after oral administration of the glycerol. OAE measurements included distortion product Otoacoustic emission (DPOAE), transiently evoked Otoacoustic emission (TEOAE) and spontaneous Otoacoustic emission(SOAE).Result: Except 2 doubtful ears had positive Hennerbert signs, the other tested ears were normal in external and middle ear assessments and PTA. 34 normal ears elicited normal OAE, the glycerol test had no effect on every frequency of both the level, S/N ratio of DPOAE and the correlation, S/N ratio of TEOAE (p>0.05) . There were no differences of gender and left or right ear either (p>0.05) . 40 doubtful ears were all detected when the patients themselves felt vertigo, after the glycerol test the symptom were relieved with the different degree and 2 ears with positive Hennerbert signs turned to negative. During the glycerol test, the level and S/N ratio of DPOAE at 0.5KHz, the correlation and S/N ratio of TEOAE at 1.0KHz had significant changes among all of the frequencies (p>0.05) . To compare with the control group, the doubtful group showed significant changes in the level and S/N ratio of DPOAE at 0.5KHz (level: the doubtfulgroup 5.27±8.64 dB, the control group -1.15±4.18 dB; S/N ratio: the doubtful group 3.85±6.27 dB, the control group-0.79±2.80 dB), in the S/N ratio at 1.0 KHz(the doubtful group 2.43±4.38 dB, the control group -0.47±3.97 dB) (p>0.05); So did in the correlation and S/N ratio of TEOAE at 1.0KHz (correlation: the doubtfdl group 17.10±23.65 %, the control group 2.21±15.94 %; S/N ratio: the doubtful group 2.12±2.85 dB, the control group -0.36±3.23 dB), in the correlation at 2.0KHz (the doubtful group 6.53±26.83%, the control group -0.65±14.72 %) (p>0.05). We also found there were a certain positive linear trend between the level and S/N ratio of DPOAE, the correlation and S/N ratio of TEOAE. SOAE were detected in 18 ears of the 40 doubtful ears at 623Hz, among them after glycerol test SOAE disappeared in 11 ears. Conclusion: The present results suggest that for the ears with probable Meniere's disease, which may be in the early phase of the endolymphatic hydrops, the most significant changes are showed in the level of DPOAE at 0.5KHz, in the correlation and S/N ratio of TEOAE at 1.0KHz during the glycerol test; According to this, we can use OAE glycerol test to offer an objective basis for an early diagnosis to the patients of the probable Meniere's disease; When using this detection, the changes of S/N ratio should be paid more attention to.