Study of cochlear microphonic potentials in auditory neuropathy

Soares, Ilka do Amaral; Menezes, Pedro de Lemos; Carnaúba, Aline Tenório Lins; de Andrade, Kelly Cristina Lira; Lins, Otávio Gomes

doi:10.1016/j.bjorl.2015.11.022

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Review articles • Braz. j. otorhinolaryngol. 82 (6) • Nov-Dec 2016 • https://doi.org/10.1016/j.bjorl.2015.11.022 copy

Study of cochlear microphonic potentials in auditory neuropathy^☆ ☆ Please cite this article as: Soares IA, Menezes PL, Carnaúba AT, de Andrade KC, Lins OG. Study of cochlear microphonic potentials in auditory neuropathy. Braz J Otorhinolaryngol. 2016;82:722-36.

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Abstract

Introduction:

Auditory Neuropathy/Dyssynchrony is a disorder characterized by the presence of Otoacoustic Emissions and Cochlear Microphonic Potentials, an absence or severe alteration of Brainstem Evoked Auditory Potential, auditory thresholds incompatible with speech thresholds and altered acoustic reflexes. The study of the Cochlear Microphonic Potential appears to be the most important tool for an accurate diagnosis of this pathology.

Objective:

Determine the characteristics of the Cochlear Microphonic in Auditory Neuropathy/Dyssynchrony using an integrative review.

Methods:

Bibliographic survey of Pubmed and Bireme platforms and MedLine, LILACS and SciELO data banks, with standardized searches up to July 2014, using keywords. Criteria were established for the selection and assessment of the scientific studies surveyed, considering the following aspects: author, year/place, degree of recommendation/level of scientific evidence, objective, sample, age range, mean age, tests, results and conclusion.

Results:

Of the 1959 articles found, 1914 were excluded for the title, 20 for the abstract, 9 for the text of the article, 2 for being repeated and 14 were selected for the study.

Conclusion:

The presence of the Cochlear Microphonic is a determining finding in the differential diagnosis of Auditory Neuropathy/Dyssynchrony. The protocol for the determination of Cochlear Microphonic must include the use of insert earphones, reverse polarity and blocking the stimulus tube to eliminate electrical artifact interference. The amplitude of the Cochlear Microphonic in Auditory Neuropathy/Dyssynchrony shows no significant difference from that of normal individuals. The duration of the Cochlear Microphonic is longer in individuals with Auditory Neuropathy/Dyssynchrony.

KEYWORDS
Cochlear microphonic; Cochlear microphonic potential; Hearing loss

Author	Year/place	Study type	typeGrade of recommendation/level of scientificevidence	Objective	Sample	Are range in years	Mean age in years	Tests	Results	Conclusion
Deltenre et al.	1997/Belgium	Case study	C/4	Describe a new form of hearing dysfunction characterized by absent ABR, with evidence of function of the outer hair cells of the cochlea, the cochlear microphonic potential and preserved OAE	3	0-4 months	Not reported	ABR (clipped), OAE, acoustic immittance testing	OAE present, absent ABR with the presence of CM, residual hearing in one case in Behavioral Audiometry, normal tympanogram and contralateral acoustic reflexes present	OAE and ABR alone may indicate an unusual situation, but the verification only occurs with the recording of CM. Recognition of the microphonic potential isolated from routine recordings facilitated by the use of reverse polarity can be valuable for the neuro- physiological evaluation of peripheral hearing and thus, it is highly recommended.
Santarelli e Arslan	2002/Italy	Case study	C/4	Describe the findings of the ECoG in 5 patients, one adult and four children, with absent ABR and presence of DPOAE	5	3 months to 19 years	Not reported	EcogT, ABR click DPOAEs, acoustic immittance testing, Behavioral Audiometry, Vocal Audiometry	In some cases EcogT was the only reliable diagnostic tool to detect peripheral damage such as brainstem generator dysfunction	EcogT in AN provides a reliable assessment of peripheral auditory function, allowing some hypotheses about the lesion site
Rapin e Gravel	003/USA	Literature review	D5	Identify an adequate term for diseases that affect the central auditory pathway in the brainstem and, selectively, in the brain	Not applicable	Not applicable	Not applicable	Not applicable	Pure auditory neuropathy is rare, in many cases, both the 8th nerve and central auditory pathway or, in some cases, CC contribute to atypical hearing loss and speech recognition	The term AN is not adequate for cases in which the pathology is predominantly in the brainstem and should be reserved for patients with evidence that the disease involves the spiral ganglion cells and their axons
Berlin et al.	003/USA	Literature review	D5	Study of AN diagnosis and management	Not applicable	Not applicable	Not applicable	Not applicable	Studies performed in the last 20 years show that although the electroacoustic evaluation can provide good diagnosis, these responses are products of a complex physiological process and are not necessarily the true perception indicators	The attempts to characterize several aspects of the AN profile have shown that the results demonstrate a common physiological pattern due to different pathological processes, or different degrees of involvement
Rance	2005/Australia	Literature review	D5	Studying the mechanisms of AN, type of disorder, clinical profile of patients and mainly the effects of the perception of AN, which are quite different from those associated with SNHL	Not applicable	Not applicable	Not applicable	Otoscopy EcogT, ABR click, DPOAEs, acoustic immittance testing	The results show that in all patients, amplitude and CM threshold are critically dependent on the CAP threshold, showing an association of CM with both OHCandIHC	The presence of a CNS disorder seems to improve the CM amplitude. In some cases, the disappearance over time of DPOAE suggests that changes in the amplitude and duration of CM in patients with AN, result from a combination of loss of OHC and alterations in the efferent system
Santarelli et al.	2006/Italy	Observational Crosssectional	C4	Evaluate the amplitude of the CM and the hearing threshold of normal ears and ears with varying degrees of elevation in the recording of the Action Potential and compare with the corresponding values in a group of patients with AN	522	7 months to 47 years	3.1 years	Pure tone and vocal audiometry, acoustic immittance testing, OAE and ABR	The CM amplitude was significantly higher in patients with CNS disease than in those with normal hearing. CM responses were detected in all auditory patients with AN, with amplitudes and thresholds similar to those calculated for individuals with normal hearing. The duration of the CM was significantly higher in the group with AN	1. CM detection is not a distinctive characteristic of AN; 2. Patients with CNS disease showed an increase in amplitude and duration of CM, possibly due to the efferent system dysfunction; The duration, high frequency and amplitude of the CM were similar in patients with normal hearing and AN. This may result from a variable combination of the type of efferent system lesion and loss of OHC
Anastasio et al.	2008/Brazil	Case report	D5	Demonstrate the clinical applicability of EcogET in the differential diagnosis of AN when compared to ABR	1	4 years	Não de aplica	Not OAE, ABR click, applicable ABR 0.5 and 1 kHz tone pips and imaging test	A 4-year-old child, diagnosed with AN underwent the Ecog-ET with 2000 Hz tone burst in rarefaction and condensation polarities	Ecog-ET allowed a more detailed analysis of CM compared to the ABR, thus showing clinical applicability for the investigation of cochlear function in AN
Ahmmed et al.	2008/United Kingdom	Case report	C4	Study the 1 diagnostic dilemma about the presence of CM together with a significant increase in ABR thresholds in infants who fail at NHS	1	6 weeks	Not applicable	TOAE, Ecog, applicable ABR by click, by BC and Toneburst (500, 1000 and 2000 Hz)	SNHL diagnosed through clinical and family history, physical examination and imaging tests that showed enlarged vestibular aqueducts. Presence of CM in the presence of very high thresholds in the ABR click and the obtaining of thresholds for and in ABR tone pip 0.5 kHz may not be adequate to differentiate between SNHL and other conditions associated with AN	There is a need to review the NHS/AN protocol used in the UK and a new study to establish parameters to aid in the differential diagnosis of CM. A holistic and audiological medical approach is essential to manage infants who fail at the NHS
Riazi e Ferraro	2008/USA	Case reports	C4	To evaluate techniques that can optimize the recording of CM in humans. Through a variety of stimulus parameters and shielding conditions aimed at inhibiting/reducing artifacts that can contaminate the CM	11	7 children and 4 adults	Não refere	EOAT, Ecog, PEATE, por clique e toneburst (500, 1000 e 2000 Hz)	Os resultados sugerem que é mais fácil separar o MC do artefato de estímulo usando um eletrodo no Canal Auditivo e estímulos toneburst . Além disso, a blindagem eletromagnética e aterramento dos cabos de força e o transdutor acústico foram eficazes na redução e/ou eliminação artefato de estímulo	Os resultados deste estudo normativo podem ajudar a melhorar o diagnóstico do MC em NA e outros distúrbios relacionados com a audição
Talaat et al.	2009/Egypt	Prevalence Study	B2B	Detect the prevalence of AN in children and young individuals with severe to profound hearing loss	112	6-32 months	19 months	Behavioral audiometry or Visual Boost, ABR by click and Toneburst (500 Hz), acoustic immittance test	15 patients were diagnosed according to our diagnostic criteria	The prevalence of AN in the study group was 13.4%. We recommend the CM recording to be routinely tested during the evaluation of ABR whenever the results obtained are altered
Mo et al.	010/China	Observational Cross- sectional	C4	Describe the audiological findings of AN	48	6-58 months	Not reported	Behavioral audiometry, DPOAE, ABR by click and acoustic immittance test	There were 40 children with a bilateral AN profile and 8 unilateral cases; in the contralateral ears of these cases, there were 3 ears with ABR thresholds that were better than 30 dB NHL, which indicates normal auditory function, and 5 with absent or severely altered ABR. In addition, four children were diagnosed with Auditory Nerve Disabilities after further investigation through inner ear magnetic resonance imaging	The audiological results in this group of children show variability in relation to the ABR thresholds and the wave morphology, the behavioral thresholds and presence of CM and DPOAE. This may reflect the heterogeneous nature of the AN. Additionally, concomitant pathologies of the inner ear or from the middle ear disorders may disclose AN. Absent or severely altered ABR together with the presence of CM are the most reliable measures to detect AN
Shi et al.	2012/China	Observational Crosssectional	C4	Investigate the characteristics and clinical significance of CM in the diagnosis of AN in infants and children	36	3 months to 9 years	3 years	Behavioral audiometry, DPOAE, ABR by click and acoustic immittance testing	There was no significant difference in the length or amplitude of CM between the group with AN and the group with normal hearing. But the amplitudes of the CM with AN and absent DPOAE were significantly lower than in individuals with normal hearing	The CM may be very important in the diagnosis of AN. The maximum amplitudes of the CM were always found at around 0.6 ms. It is more useful for the diagnosis of AN to analyze the patterns of CM amplitudes and functions of OHC and IHC together
Liu et al.	2012/China	Retrospective cross- sectional cohort	C4	Explore a possible correlation between cochlear nerve impairment and unilateral AN	85	2-23 years	Not reported	Pure tone audiometry, DPOAE, TOAE, ABR by click and acoustic immittance testing	Eight cases were diagnosed with unilateral AN caused by cochlear nerve impairment. 7 had a type "A" tympanogram with normal bilateral OAE; the last one had unilateral type "B", tympanogram, absent OAE and present CM, according to alterations in the middle ear. ABR was absent in all patients and neuronal responses from the cochlea were not disclosed when viewed by magnetic resonance imaging of the internal auditory canal	The cochlear nerve impairment can be seen by electrophysiological evidence and may be an important cause of unilateral AN. Magnetic resonance imaging of the internal auditory canal is recommended for the diagnosis of this disease
Penido e Issac	2013/Brazil	Cohort study	C4	Determine the prevalence of AN in individuals with SNHL	2292	0-95 years	Not reported	Pure tone and vocal audiometry; acoustic immittance testing; OAE; ABR and CM	1.2% had AN. Of these, 29.6% had mild SNHL; 55.5% moderate; 7.4% severe and 7.5% profound. 14.8% were aged 0 - 20 years; 33.4% were 21 - 40 years; 44.4% were 41 - 60 years and 7.4% were older than 60 years	The prevalence of AN was 1.2% in individuals with SNHL

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[1] * Corresponding author. E-mail:ilkaamaralsoares@gmail.com (I.A. Soares).

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Study of cochlear microphonic potentials in auditory neuropathy☆ ☆ Please cite this article as: Soares IA, Menezes PL, Carnaúba AT, de Andrade KC, Lins OG. Study of cochlear microphonic potentials in auditory neuropathy. Braz J Otorhinolaryngol. 2016;82:722-36.

Abstract

Introduction:

Objective:

Methods:

Results:

Conclusion:

Study of cochlear microphonic potentials in auditory neuropathy^☆ ☆ Please cite this article as: Soares IA, Menezes PL, Carnaúba AT, de Andrade KC, Lins OG. Study of cochlear microphonic potentials in auditory neuropathy. Braz J Otorhinolaryngol. 2016;82:722-36.