Reliability of Contralateral Suppression in Evoked Distortion Product Otoacoustic Emissions

Abstract Introduction Distortion product otoacoustic emissions (DPOAE) and their suppression may be considered useful in monitoring cochlear function and the efferent auditory pathway inhibitory effect. Nonetheless, the establishment of reliable parameters of response variations is of great importance. Objectives To verify the replicability of test and retest in the research of the inhibitory effect of the efferent pathway using contralateral suppressing stimulus during DPOAE recording for clinical applicability. Methods Cross-sectional study with 48 volunteers, aged 18 to 30 years, with normal audiometric thresholds. The procedures included were audiometric and immittance measures to overrule any conductive or sensorineural conditions and DPOAE recordings without and with contralateral suppression with a 60 dBHL white noise. Distortion product otoacoustic emissions amplitudes were analyzed and compared in both conditions with Wilcoxon test, and the Spearman correlation test was used to assess test-retest reliability. Results The comparative analysis showed differences between amplitudes in test and retest conditions only in 1,500 Hz for DPOAE measures with all other tested frequencies showing no differences, and no difference was observed in all recorded frequencies in the test and retest comparison for DPOAE suppression. The degree of correlation between test and retest of DPOAE amplitude was good at 6,000 Hz and strong (r > 0.880) at the other frequencies. For DPOAE with suppression, all frequencies presented strong correlation between test and retest: 1,500 Hz (r = 0.880), 2,000 Hz (r = 0.882), 3,000 Hz (r = 0.940), and 6,000 Hz (r = 0.957). Conclusions The study found good replicability in contralateral suppression of DPOAE with potential clinical applicability, and we recommend conducting the test from 2000Hz to higher frequencies for more reliable results.

Reflejo olivococlear contralateral y su relación con ansiedad y calidad de vida en pacientes con tinnitus

Resumen Introducción: La presencia de tinnitus se asocia a un incremento del nivel de ansiedad y empeoramiento de la calidad de vida, sin embargo, aún no existe claridad de si el sistema eferente auditivo podría influir en estas relaciones. Objetivo: Determinar si las amplitudes de las emisiones otoacústicas por producto de distorsión (EOAPD) y el efecto supresor del reflejo olivococlear gatillado con ruido contralateral (ROC) se asocian al grado del impacto psicoemocional y nivel de ansiedad en pacientes con tinnitus. Material y Método: Se evaluaron las amplitudes de EOAPD y magnitud del ROC para cada oído de manera independiente en una cohorte de 32 sujetos tinnitus y 26 controles, cuyos valores fueron correlacionados con State-Trait Anxiety Inventory (STAI) y Tinnitus Handicap Inventory (THI). Resultados: Los pacientes con tinnitus tuvieron una correlación significativa entre la magnitud del ROC del oído izquierdo y los puntajes en las pruebas de STAI y THI. Conclusión: Una mayor carga de ansiedad y peor calidad de vida en sujetos con tinnitus puede estar asociada con un empeoramiento del efecto supresor del ROC de la vía eferente auditiva.

Abstract Introduction: Tinnitus is associated with an increase in the degree of anxiety and with worse quality of life. However, whether there are relations between the function of the auditory efferent system and anxiety and tinnitus distress levels is not known. Aim: To determine possible associations between the distortion product otoacoustic emission (DPOAE) amplitudes and the suppressing effect of the olivo-cochlear reflex (OCR) with anxiety and psycho-emotional impact in tinnitus. Material and Method: DPOAE amplitudes and OCR strength were evaluated for each ear independently in a cohort of 32 tinnitus and 26 controls, whose values were correlated with the State-Trait Anxiety Inventory (STAI) and Tinnitus Handicap Inventory (THI). Results: A significant correlation of STAI and THI scales with the OCR strength measured in the left ear was found in subjects with tinnitus. Conclusion: A higher anxiety load and worse quality of life in subjects with tinnitus may be associated with an impaired olivocochlear reflex suppressing effect.

Desde la corteza auditiva a la cóclea: progresos en el sistema eferente auditivo / From auditory cortex to cochlea: progress in the auditory efferent system

El sistema eferente auditivo está constituido por el sistema olivococlear y por vías descendentes que provienen de la corteza auditiva y se dirigen a la cóclea. El sistema olivococlear se divide en una porción medial y una lateral, con neuronas que inervan a las células ciliadas externas y a fibras del nervio auditivo respectivamente. El principal neurotransmisor de las sinapsis olivococleares es acetilcolina, y tanto las células ciliadas externas como las fibras del nervio auditivo poseen receptores para esta molécula. El sistema eferente córtico-coclear se origina en la capa V y VI de la corteza auditiva y proyecta a los colículos inferiores y complejo olivar superior, donde a través del sistema olivococlear se conecta con el órgano receptor auditivo. En este artículo se revisan importantes hallazgos obtenidos en los últimos años que involucran (i) nuevos neurotransmisores y receptores del sistema eferente auditivo; (ii) vías descendentes de la corteza auditiva y su rol fisiológico sobre las respuestas cocleares y (iii) rol del sistema eferente auditivo en patologías audiológicas y neuropsiquiátricas.

The auditory efferent system is composed by the olivocochlear fibers and descending projections that originate in the auditory cortex and end in the cochlea. The olivocochlear system is divided into a medial and lateral division, with fibers directed to the outer hair cells and to the auditory nerve fibers respectively. It is known that acetylcholine is the main neurotransmitter of the olivocochlear synapses and that outer hair cells and auditory nerve fibers have receptors to this molecule. The cortico-cochlear efferent system originates in layers V and VI of the auditory cortex. These descending projections are directed to the inferior colliculus and superior olivary complex, a site in which the olivocochlear fibers emerge and connect the brain with the cochlear receptor. In this article recent discoveries obtained in the last years are reviewed: (i) new neurotransmitters and receptors of the olivocochlear system; (ii) anatomy and physiology of descending pathways from the auditory cortex to the cochlea and, (iii) clinical role of auditory efferents in audiological and neuropsychiatric pathologies.

The Hearing Status and the Functions of Efferent System in Autistic Children / 听力学及言语疾病杂志

Objective To assess hearing and efferent system functions of autistic children.Methods Tests were performed on 30 Autistic children and 15 normal children to evaluate hearing objectively by using otoacoustic emission (OAE) and auditory brainstem response (ABR).The efferent system functions were analyzed through contralateral suppression in OAE.Results The mean ABR Ⅰ-Ⅴ interpeak latencies (IPLs) in children with Autism were significantly reduced than that in the control group.The amplitudes of OAE at 1 kHz and 2 kHz in autistic children were significantly different in two groups.There were no significant differences in contralateral suppressions between the Autistic children and the control.Conclusion Hearing impairment may be more common in children with Autism than in normal children,while for a few Autistic children,their efferent system functions are affected.

The Change of Acoustic Stapedius Reflex Amplitude with the Stimulation of the Wide Band Noise in Sound Field / 听力学及言语疾病杂志

Objective To investigate the effects of different intensity of wide band noise on acoustic stapedius reflex amplitude in sound field. Methods Acoustical reflex amplitude(at ART+10 dB)were obtained at three fre-quencies (1,2, 4 kHz) from 80 normally hearing subjects with wide band noise at 30,40,50 and 60 dB SL in sound field. Results Acoustical reflex amplitude was significantly decreased in the presence of wide band noise (P 0. 01). The most significant decrease of acoustic reflex amplitude could be observed in the present of 40 dB SL wide band noise. In comparison with the 1 kHz group, significant decrease was found in 2 kHz group and 4 kHz group(P <0. 01),but there was no difference between the 2 kHz group and 4 kHz group(P>0.05). Conclusion Since the decrease of the acoustic stapedius reflex amplitude is mediated by the auditory efferent system in sound field, in clini-cal practice the function of the auditory efferents can be evaluated by testing the change of acoustic stapedius reflex amplitude with the stimulation of the wide band noise in sound field.

Analysis of Auditory Efferent System Function in the Subjects with Tinnitus / 听力学及言语疾病杂志

Objective To explore the function of auditory efferent system in the subjects with tinnitus.Methods Effects of contralateral stimulation on otoacoustic emission in 24 subjects with tinnitus were measured for analysis the function of the medial olivo-cochlea system. Results ①The incidence of SOAE 41.7% in 24 normal ears,and 37.5%,20%,33.3% in different groups of tinnitus and the amplitude were suppressed. ②The suppressive amplitude of TEOAE was 2.1?0.8 dB SPL in 24 normal ears and 1.9?0.8 dB SPL in 16 ears with tinnitus, but there was no suppression in 8 ears with tinnitus. ③There were observable suppression in 3 ears, but 2 ears had no contralateral suppression in tinnitus with normal hearing group. 8 ears showed suppression in tinnitus with hearing loss, 2 ears had no changes. 4 ears had no contralateral suppression in tinnitus subjects with low frequency hearing loss.Conclusion The effects of suppression in the normal ears of subjects with tinnitus is as normal subjects, but those different results of suppression in the tinnitus ears indicate that mechanism of tinnitus is multiformity.