Distortion-product otoacoustic emission tests evaluate cochlear function and differentiate cochlear and vestibular schwannoma.

OBJECTIVES: (1) To investigate cochlear function in patients with acoustic neuroma by distortion-product otoacoustic emission tests and (2) to evaluate the utility of this method for identifying the nerve origin of acoustic neuroma. STUDY DESIGN: Diagnostic test assessment. SETTING: Community hospital. METHODS: The study included 196 patients with unilateral acoustic neuroma who were surgically treated in our hospital between April 2008 and March 2011. In all patients, pure-tone audiometry and distortion-product otoacoustic emission tests were conducted before surgery, and tumor size was measured on magnetic resonance imaging. RESULTS: Superior vestibular schwannoma (n = 112), inferior vestibular schwannoma (n = 80), and cochlear schwannoma (n = 4) were observed. Positive results of distortion-product otoacoustic emission tests were observed in 11 patients with superior vestibular schwannoma, 14 with inferior vestibular schwannoma, and 3 with cochlear schwannoma. They were predictive of cochlear schwannoma, with 75.0% sensitivity (95% confidence interval [CI], 30.6-95.4) and 87.0% specificity (95% CI, 86.1-87.4). Retrocochlear hearing loss was detected in 5 patients with inferior vestibular schwannoma and 1 with cochlear schwannoma. It was also predictive of cochlear schwannoma. This criterion showed 25.0% sensitivity (95% CI, 4.7-66.1) and 97.4% specificity (95% CI, 97.0-98.3). CONCLUSION: Percentages of patients with positive results on distortion-product otoacoustic emission tests and those with retrocochlear hearing loss differed by nerve origin. Distortion-product otoacoustic emission tests can be of some assistance in differentiating cochlear and vestibular schwannoma.

Hearing Evaluation in Patients with Exfoliative and Primary Open-Angle Glaucoma.

OBJECTIVE: The aim of this prospective study was to audiologically evaluate consecutive glaucoma patients with or without exfoliation. STUDY DESIGN: Prospective study. SETTING: Glaucoma Unit and Audiology Department at a university hospital. SUBJECTS AND METHODS: Consecutive subjects with exfoliative glaucoma (XFG) or primary open-angle glaucoma (POAG) aged between 50 and 70 years were enrolled. Auditory thresholds at 0.5, 1.0, 2.0, 4.0, and 8.0 Hz were measured bilaterally. Cochlear activity was assessed by recording distortion product otoacoustic emissions (DPOEs). Functional changes in the retrocochlear auditory pathway were evaluated by auditory brainstem responses (ABRs). RESULTS: One hundred and ten patients with XFG and 85 patients with POAG who presented in a glaucoma clinic were investigated. The mean age of study patients was 66.2 ± 5.6 years; range, 50-70 years). The odds of pathologic ABR central transmission time (interpeak latencies I-III, III-V, and I-V and waves I, III, and V) were 4.34 times higher in patients with XFG than in patients with POAG (95% confidence interval [CI], 2.22-8.49; P < .001). This significant association remained after adjusting for sex and age (odds ratio [OR] 4.12; 95% CI, 2.07-8.22; P < .001). Furthermore, the odds of ABR remained significantly higher in patients with XFG than in patients with POAG (OR 4.36; 95% CI, 2.10-9.06; P < .001) after controlling for systemic diseases (arterial hypertension, coronary heart disease, high cholesterol, and stroke). CONCLUSION: In the first study to compare XFG and POAG monitoring of the peripheral and central auditory pathway, it has been documented that XFG patients show a greater prevalence of retrocochlear pathology.

Evoked response audiometry in scrub typhus: prospective, randomised, case-control study.

OBJECTIVE: To investigate the hypothesis of cochlear and retrocochlear damage in scrub typhus, using evoked response audiometry. STUDY DESIGN: Prospective, randomised, case-control study. METHODS: The study included 25 patients with scrub typhus and 25 controls with other febrile illnesses not known to cause hearing loss. Controls were age- and sex-matched. All subjects underwent pure tone audiometry and evoked response audiometry before commencing treatment. RESULTS: Six patients presented with hearing loss, although a total of 23 patients had evidence of symmetrical high frequency loss on pure tone audiometry. Evoked response audiometry found significant prolongation of absolute latencies of wave I, III, V, and wave I-III interpeak latency. Two cases with normal hearing had increased interpeak latencies. These findings constitute level 3b evidence. CONCLUSION: Findings were suggestive of retrocochlear pathology in two cases with normal hearing. In other patients, high frequency hearing loss may have led to altered evoked response results. Although scrub typhus appears to cause middle ear cochlear and retrocochlear damage, the presence of such damage could not be fully confirmed by evoked response audiometry.

[Auditory brainstem responses evaluation of retrocochlear disease in workers from a general hospital exposed to noise]. / Aplicação da audiometria troncoencefálica na detecção de perdas auditivas retrococleares em trabalhadores de manutenção hospitalar expostos a ruído.

The main purpose of this cross-sectional study was to investigate the presence of retrocochlear disease in a group of maintenance workers from a general hospital, who presents a history of noise exposure. Thirty one workers of three engineering sections with age range from 25 to 60 years and continuous noise exposure from 2 and 45 years, were examined. The evaluation included an audiometric occupational selection and auditory brainstem responses (ABR). ABR abnormalities were detected in seven patients (22.6%) and it was found latency increase of waves III (14.3%) and V (28.6%), and interpeak prolongation I-III (71.4%), III-V (28.6%) and I-V (85.7%). Among 35 ears with normal audition - right, left or both -, four (11,4%) ears presented retrocochlear disease. The high retrocochlear disease prevalence in workers exposed to noise lead us to suppose that this disturbance is more frequent than usually found; therefore it is underestimated in workers diagnostic evaluation. The presence of this kind of disturbance, even with the absence of audiometric alterations, suggests that ABR is more sensitive than the tonal audiometry for noise induced hearing loss investigation.

Aplicação da audiometria troncoencefálica na detecção de perdas auditivas retrococleares em trabalhadores de manutenção hospitalar expostos a ruído / Auditory brainstem responses evaluation of retrocochlear disease in workers from a general hospital exposed to noise

O objetivo principal deste estudo seccional foi averiguar a presença de comprometimento auditivo retrococlear num grupo de trabalhadores de manutenção de um hospital de grande porte com histórico de exposição a ruído. Foram avaliados 31 trabalhadores de três setores da divisão de engenharia entre 25 e 60 anos e com exposição contínua a ruído entre 2 e 45 anos. O processo avaliativo contou com triagem audiométrica ocupacional e audiometria troncoencefálica (ATE). Foram detectadas anormalidades na ATE em sete pacientes (22,6 por cento), caracterizadas por aumento de latências de ondas III (14,3 por cento) e V (28,6 por cento); prolongamento dos interpicos I-III (71,4 por cento), III-V (28,6 por cento) e I-V (85,7 por cento). Das 35 orelhas com audição normal (três unilateralmente e 32 bilateralmente), quatro (11,4 por cento) apresentaram comprometimento retrococlear. A alta prevalência de comprometimento retrococlear no grupo induz supor que tal distúrbio seja mais frequente que o encontrado e esteja sendo subestimado na investigação diagnóstica desses trabalhadores. A ocorrência desses resultados sem a presença de alterações audiométricas sugere que a ATE seja mais sensível que a audiometria tonal na investigação de perda auditiva provocada por ruído, por isso sua utilização deva ser incentivada.

The main purpose of this cross-seccional study was to investigate the presence of retrocochlear disease in a group of maintenance workers from a general hospital, who presents a history of noise exposure. Thirty one workers of three engineering sections with age range from 25 to 60 years and continuous noise exposure from 2 and 45 years, were examined. The evaluation included an audiometric occupational selection and auditory brainstem responses (ABR). ABR abnormalities were detected in seven patients (22.6 percent) and it was found latency increase of waves III (14.3 percent) and V (28.6 percent), and interpeak prolongation I-III (71.4 percent), III-V (28.6 percent) and I-V (85.7 percent). Among 35 ears with normal audition right, left or both , four (11,4 percent) ears presented retrocochlear disease. The high retrocochlear disease prevalence in workers exposed to noise lead us to suppose that this disturbance is more frequent than usually found; therefore it is underestimated in workers diagnostic evaluation. The presence of this kind of disturbance, even with the absence of audiometric alterations, suggests that ABR is more sensitive than the tonal audiometry for noise induced hearing loss investigation.

Hearing loss in vestibular schwannomas: analysis of cochlear function by means of distortion-product otoacoustic emissions.

OBJECTIVE: We investigated cochlear function in a group of patients affected by vestibular schwannoma (VS), by means of recording distortion-product otoacoustic emissions (DPOAEs). METHODS: Between January 1996 and January 2007, we observed 183 patients affected by unilateral VS. DPOAEs, compared to the corresponding hearing thresholds, were subjectively classified into three categories: "compatible" with hearing function, "cochlear" and "retro-cochlear". We also related the responses to some clinical variables (tumor size, intracanalicular tumor and radiologic appearance of the internal auditory canal). Statistical analysis was performed. RESULTS: In 137 cases (74.9%), DPOAEs were as expected based on audiometry responses, while in 11 patients (6%) a "cochlear" DP-gram was recorded and in 35 patients (19.1%) DPOAEs evidenced a "retro-cochlear" pattern. In eight cases we detected acoustic responses despite a profound hearing loss. No statistically significant data merged from the comparison between "cochlear" and "retro-cochlear" responses and the clinical variables. CONCLUSION: Our results confirm that sensorineural hearing loss due to VS can be of sensory and/or neural origin. DPOAEs still remain just a complementary auditory test; nevertheless, in case of severe or profound unilateral hearing loss, recorded acoustic responses may be suspicious for the presence of a vestibular schwannoma.

[Audiological characteristics and localization of lesions in children with retrocochlear auditory nerve impairment].

OBJECTIVE: To explore the clinic characteristics, audiological characteristics and location of lesions in children with retrocochlear auditory nerve impairment which, including auditory neuropathy characterized by severely abnormal results of ABR and normal results of DPOAE. METHODS: Between 2002 and 2006, eighty-six cases (165 ears) with severely abnormal ABR but normal results of DPOAE were enrolled in the study group. The mean patient age was one year and one-month-old, with a range of 8 days to 7 years. The cases with abnormal conductive function were excluded. The cases with severely abnormal ABR and normal cochlear functions as measured by DPOAE and without abnormal conductive function were selected as the cochlear lesion group. Some same age healthy children without hearing loss were subjected as normal control group. The latency and amplitude of waves I, III and V, the inter peak latency I-III was compared among the three group. RESULTS: (1) Fifty-one cases (59.3%) had a history of hypercholesterolemia during neonatal period, but 40 cases (46.51%) had a severe hypercholesterolemia and 11 cases (12.79%) had mild or moderate hypercholesterolemia. Clinical features common among the population included a history of dyskinesia [n = 40 (46.51%)], hearing and language disorder [n = 10 (11. 63%)]. Thirty-two cases (37.2%) were accompanied by cerebral palsy . (2) Among the 165 ears, absent ABRs to click stimuli presented at 103 dB was in 103 ears, only wave I was developed in 27 ears and only wave V was developed in 19 ears,wave I and III in 13 ears and differentiated wave I and V in 3 ears. (3) When compared to control group, the latency of wave I was prolonged and amplitude of wave I was lower in cases with only wave I developed (t = -6.75 and 2.58, P < 0.05). For for cases with only wave I and III differentiated, the latency and amplitude of wave I was the same but the latency of wave III was prolonged and amplitude of wave III was lower while interpeak latency I-III was prolonged. CONCLUSIONS: Auditory neuropathy which was characterized by severely abnormal ABR was the most common type of retrocochlear auditory nerve impairment. It was mainly due to a disorder of VIII nerve. The pathologies that affect higher levels of the auditory pathway, from the brainstem to the auditory cortex, might be the main sites of lesion in cases with only wave I developed. Superior olivary nucleus where wave III was generated and higher levels of the auditory pathway might be the main sites of lesion in cases with wave I and III differentiated. The low-amplitude wave V was not characteristics of auditory neuropathy. Cerebral cortex, brain stem auditory nucleus and VIII nerve might be damaged successively in cases with retrocochlear auditory nerve impairment induced by hypercholesterolemia.