Topic 3.10. Auditory and vestibular function in Friedreich ataxia

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This chapter of the Clinical Management Guidelines for Friedreich Ataxia and the recommendations and best practice statements contained herein were endorsed by the authors and the Friedreich Ataxia Guidelines Panel in 2022.

Topic Contents

3.10.1 The effects of Friedreich ataxia on auditory and vestibular function
3.10.2 Functional consequences of disturbance of auditory and vestibular function
3.10.3 Assessment and management of auditory and vestibular disturbance
3.10.3.1 Assessment of auditory function
3.10.3.2 Interventions for auditory disturbance
3.10.3.3 Assessment of vestibular function
3.10.3.4 Intervention for vestibular disturbance

Disclaimer / Intended Use / Funding

Disclaimer
The Clinical Management Guidelines for Friedreich ataxia (‘Guidelines’) are protected by copyright owned by the authors who contributed to their development or said authors’ assignees.

These Guidelines are systematically developed evidence statements incorporating data from a comprehensive literature review of the most recent studies available (up to the Guidelines submission date) and reviewed according to the Grading of Recommendations, Assessment Development and Evaluations (GRADE) framework © The Grade Working Group.

Guidelines users must seek out the most recent information that might supersede the diagnostic and treatment recommendations contained within these Guidelines and consider local variations in clinical settings, funding and resources that may impact on the implementation of the recommendations set out in these Guidelines.

The authors of these Guidelines disclaim all liability for the accuracy or completeness of the Guidelines, and disclaim all warranties, express or implied to their incorrect use.

Intended Use
These Guidelines are made available as general information only and do not constitute medical advice. These Guidelines are intended to assist qualified healthcare professionals make informed treatment decisions about the care of individuals with Friedreich ataxia. They are not intended as a sole source of guidance in managing issues related to Friedreich ataxia. Rather, they are designed to assist clinicians by providing an evidence-based framework for decision-making.

These Guidelines are not intended to replace clinical judgment and other approaches to diagnosing and managing problems associated with Friedreich ataxia which may be appropriate in specific circumstances. Ultimately, healthcare professionals must make their own treatment decisions on a case-by-case basis, after consultation with their patients, using their clinical judgment, knowledge and expertise.
Guidelines users must not edit or modify the Guidelines in any way – including removing any branding, acknowledgement, authorship or copyright notice.

Funding
The authors of this document gratefully acknowledge the support of the Friedreich Ataxia Research Alliance (FARA). The views and opinions expressed in the Guidelines are solely those of the authors and do not necessarily reflect the official policy or position of FARA.

3.10 Auditory and vestibular function in Friedreich ataxia

Gary Rance and Thierry Morlet

This chapter describes the effects of Friedreich ataxia on auditory and vestibular function, the functional consequences of these effects, and strategies for assessing and managing auditory and vestibular disturbance. In making recommendations for management, the authors were tasked with answering the question:

For individuals with Friedreich ataxia, what management strategies could be implemented for disturbance of auditory function?

3.10.1 The effects of Friedreich ataxia on auditory and vestibular function

Auditory pathway abnormality is a consistently reported feature of Friedreich ataxia (FRDA). While sound detection is typically normal or near-normal (1-3), almost all individuals with FRDA will (eventually) show evidence of disordered neural conduction in the central auditory pathways (auditory neuropathy) and abnormal perception of complex signals including speech.

Peripheral auditory function (that is the physiology of the middle and inner ear) is generally unaffected in individuals with FRDA, but neural activity is abnormal. Electrophysiologic assessment typically reveals absent or distorted potentials from the cochlear nerve and auditory brainstem (3-5) consistent with auditory nerve axonopathy (3, 6, 7). This result pattern is in accordance with histological evidence showing preserved cochlear structures (organ of corti and hair cells) and selective loss of auditory nerve fibers (8).

Abnormalities in the function of the vestibular system are also a consistently reported feature of FRDA. The vestibular function is diminished and oculomotor abnormalities are common, as revealed with caloric, rotatory and head impulse tests (9-13). The presence of abnormal eye movement at early onset of FRDA is a sign of disease severity (10) and the vestibulo-ocular responses and gaze stability control are correlated with progression of the disease. Abnormal vestibular findings in individuals with FRDA are consistent with damage to the vestibular end organ, the vestibular nerve or the vestibular brainstem nucleus (8, 14).

3.10.2 Functional consequences of disturbance of auditory and vestibular function

The perceptual effects of auditory pathway disorder in individuals with FRDA are distinct from those caused by peripheral hearing loss. Where cochlear damage results in impaired sound detection thresholds and distortion of pitch perception, auditory neuropathy associated with FRDA results in disruption of temporal (timing) cues (3). The functional consequences of this temporal distortion are variable, but typically severe. The majority of individuals with FRDA show impaired speech understanding in background noise (3, 15) and report impaired communication (16), which worsens with disease progression.

FRDA is characterized by severe and widespread anomalies in the oculomotor and vestibular systems. When combined with ataxia, these anomalies can further impair the autonomy of affected individuals.

3.10.3 Assessment and management of auditory and vestibular disturbance

3.10.3.1 Assessment of auditory function

Auditory evaluation should assess both peripheral function and the central auditory pathways and include the following:

1. Sound detection thresholds (audiogram)
2. Speech perception

○ functional hearing capacity in quiet and background noise

3. Auditory evoked potentials

○ auditory brainstem response (ABR)
○ cochlear microphonic (CM)

4. Otoacoustic emissions (OAE)
5. Hearing disability survey

3.10.3.2 Interventions for auditory disturbance

Instruction in ‘listening tactics’ can be beneficial for all individuals with hearing difficulties (17). The aim of these strategies is to help the listener optimize social interaction by controlling the communication environment. This may involve a range of measures including minimization of background noise and maximization of visual (lip-reading) cues.

Conventional hearing aids tend not to be useful in listeners with FRDA as they are designed to make sounds louder (which is typically not required for this population) and do not overcome the auditory neural distortion typically associated with FRDA (18, 19).

There is no clear evidence as to whether or not cochlear implants help individuals with FRDA. A handful of case studies have been presented and outcomes have been mixed (18, 19). Cochlear implant results in populations with other neurodegenerative diseases involving auditory axonopathy have been also been variable (20).

Remote-microphone listening devices, may improve day-to-day listening and general communication in individuals with FRDA (16). These systems transmit speech signals (detected by a lapel microphone worn by the speaker) directly to ear-level receivers worn by the listener. As such, they improve access to the signal because the speech is louder (relative to the background noise) at the listener’s ear.

3.10.3.3 Assessment of vestibular function

Exploring vestibular function can help clinicians with the differential diagnosis of progressive ataxia syndromes. Patients with FRDA would benefit from the following vestibular assessment:

1. Video head impulse test (v-HIT)
2. Earth vertical axis rotation (EVAR)
3. Vestibular evoked myogenic potentials (VEMPs)

3.10.3.4 Intervention for vestibular disturbance

Physical and occupational therapy may ease some symptoms of vestibular disturbance and help improve quality of life in some patients.

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Please note: Recommendations are systematically developed evidence statements incorporating data from a comprehensive literature review of the most recent studies available (up to the Guidelines submission date) and reviewed according to the Grading of Recommendations, Assessment Development and Evaluations (GRADE) framework © The Grade Working Group. Best Practice Statements are commonly accepted practices, as such formal rating of the quality of evidence by the GRADE process is not indicated. In addition if recommendations from the 2014 guidelines were deemed still relevant, although unable to undergo the scrutiny from a GRADE framework, they were also included as best practice statements.

Assessment of auditory and vestibular disturbance

QUESTION: Should auditory/vestibular assessment versus no auditory/vestibular assessment be used for all people with Friedreich ataxia?
[sg_popup id=”587″ event=”click”][/sg_popup]STRENGTH OF RECOMMENDATION: ↑↑
[sg_popup id=”658″ event=”click”][/sg_popup]LEVEL OF EVIDENCE: ⨁⨁◯◯

RECOMMENDATION: We recommend that all individuals with Friedreich ataxia undergo auditory and vestibular assessment over not having these assessments.

JUSTIFICATION: Audiological function was identified by the Patient & Parent Advisory Panel as a priority. Although there is no published evidence in Friedreich ataxia, in other populations undiagnosed hearing deficit has been shown to exacerbate communication difficulties, resulting in increased social isolation and reduced quality of life.

As with the auditory brainstem responses, vestibulo-ocular responses and gaze stability control are correlated to the disease severity and disease progression and could be used as markers of severity and progression. Therefore, testing these functions should be considered as additional tools for monitoring the evolution of the disease.

All individuals with Friedreich ataxia should benefit from a vestibular and auditory assessment including at least v-HIT, EVAR, VEMPS, pure tone audiometry, OAEs, ABR and a speech discrimination in background noise test.

SUBGROUP CONSIDERATION: This recommendation is for all individuals with Friedreich ataxia. Developmental issues in pediatric populations should be considered: hearing impairment in children can affect speech, language, social and academic development.

Evidence to Recommendation Table PDF

Hearing aids

QUESTION: Should hearing aids (including cochlear implants) versus no hearing aids/cochlear implants be used for all people with Friedreich ataxia?
[sg_popup id=”587″ event=”click”][/sg_popup]STRENGTH OF RECOMMENDATION: —
[sg_popup id=”658″ event=”click”][/sg_popup]LEVEL OF EVIDENCE: ⨁⨁◯◯

RECOMMENDATION: We cannot recommend either the use or non-use of hearing aids (or cochlear implants) for individuals with Friedreich ataxia with auditory deficits.

JUSTIFICATION: The management of auditory deficits was identified by the Patient and Parent Advisory Panel as a priority. Published evidence indicates that the prevalence of hearing difficulties is higher in people with Friedreich ataxia compared to the general population.

There is very limited evidence related to the efficacy of either hearing aids or cochlear implants in people with Friedreich ataxia, but findings in other groups with auditory neuropathy due to neurodegenerative disease suggest that outcomes with the use of hearing aids are poor and outcomes with cochlear implants are variable.

SUBGROUP CONSIDERATION: This recommendation is for individuals with Friedreich ataxia with auditory deficits. Developmental issues in pediatric populations should be considered: hearing impairment in children can affect speech, language, social and academic development.

Evidence to Recommendation Table PDF

Amplification devices

QUESTION: Should amplification versus cochlear implants be used for all people with Friedreich ataxia?
[sg_popup id=”587″ event=”click”][/sg_popup]STRENGTH OF RECOMMENDATION: —
[sg_popup id=”658″ event=”click”][/sg_popup]LEVEL OF EVIDENCE: ⨁⨁◯◯

RECOMMENDATION: We cannot recommend the use of amplification devices over cochlear implants for individuals with Friedreich ataxia with auditory deficits.

There is very limited evidence related to the efficacy of either amplifications devices or cochlear implants in people with Friedreich ataxia, but findings in other groups with auditory neuropathy due to neurodegenerative disease suggest that outcomes with the use of amplification devices are poor and outcomes with cochlear implants are variable.

Evidence to Recommendation Table PDF

Remote-microphone listening devices

QUESTION: Should remote-microphone (FM) listening devices versus no devices be used for all people with Friedreich ataxia?
[sg_popup id=”587″ event=”click”][/sg_popup]STRENGTH OF RECOMMENDATION: ↑
[sg_popup id=”658″ event=”click”][/sg_popup]LEVEL OF EVIDENCE: ⨁⨁◯◯

RECOMMENDATION: We suggest using remote-microphone listening devices over not using any devices for individuals with Friedreich ataxia with auditory deficits.

JUSTIFICATION: The management of auditory deficits was identified by the Patient and Parent Advisory Panel as a priority. Published evidence indicates that the prevalence of hearing difficulties is higher in in people with Friedreich ataxia compared to the general population.

Available evidence suggests that remote-microphone listening systems can improve speech perception in everyday (noisy) listening circumstances and aid communication.

Non-ambulant individuals are potentially less able to control listening/communication situations; for example, physical distance from the speaker and from noise sources in the environment. As such, they are likely to derive greater device benefit as the signal provided by the system is consistent regardless of the distance between speaker and listener.

Evidence to Recommendation Table PDF

Assessment of auditory and vestibular function should form part of the standard Friedreich ataxia management protocol. Each individual should be evaluated on an annual basis or more regularly if the individual notices a change in auditory performance or balance.

Lay summary of clinical recommendations for disturbance of auditory and vestibular function in Friedreich ataxia

Why these recommendations?

Hearing loss affects many individuals with Friedreich ataxia and the degree of hearing difficulty often increases as the disease progresses. Although sound detection may remain normal or close to normal, most people report high levels of listening and communication difficulties in everyday listening circumstances. Understanding of speech is often disrupted, particularly in noisy environments. This may significantly affect quality of life.

What does this mean for you as a person living with Friedreich ataxia or caring for someone living with Friedreich ataxia?
It is recommended that a person with Friedreich ataxia have a comprehensive auditory (hearing) and vestibular (balance) evaluation at the time of diagnosis followed by regular review. These assessments might be yearly, or more often if a sudden change in hearing or balance occurs.
The best management of hearing problems in Friedreich ataxia is currently unclear. There is very limited evidence as to whether interventions such as hearing aids or cochlear implants can provide enough benefit. There is, however, some evidence to suggest that using non-invasive remote microphone listening systems can improve understanding of speech and communication in everyday (noisy) listening circumstances. These may be particularly helpful for children in school classrooms and for non-ambulant individuals who cannot easily move away from noisy situations.

Who are these recommendations specifically for?
These recommendations are for individuals with Friedreich ataxia with hearing problems.

Thierry Morlet, PhD
Senior research scientist, Nemours Children’s Health, Wilmington, Delaware, USA
Email: thierry.morlet@nemours.org

Gary Rance, BEd, Dip Aud, MSc, PhD
Head of Department, Audiology & Speech Pathology, The University of Melbourne, Parkville, Victoria, Australia
Email: grance@unimelb.edu.au

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It is our expectation that going forward individual topics can be updated in real-time in response to new evidence versus a re-evaluation and update of all topics simultaneously.