Auditory Perception in Individuals with Friedreich’s Ataxia

Abstract

Introduction: Friedreich’s ataxia (FRDA) is an inherited ataxia with a range of progressive features including axonal degeneration of sensory nerves. The aim of this study was to investigate auditory perception in affected individuals. Methods: Fourteen subjects with genetically defined FRDA participated. Two control groups, one consisting of healthy, normally hearing individuals and another comprised of subjects with sensorineural hearing loss, were also assessed. Auditory processing was evaluated using structured tasks designed to reveal the listeners’ ability to perceive temporal and spectral cues. Findings were then correlated with open-set speech understanding. Results: Nine of 14 individuals with FRDA showed evidence of auditory processing disorder. Gap and amplitude modulation detection levels in these subjects were significantly elevated, indicating impaired encoding of rapid signal changes. Electrophysiologic findings (auditory brainstem response, ABR) also reflected disrupted neural activity. Speech understanding was significantly affected in these listeners and the degree of disruption was related to temporal processing ability. Speech analyses indicated that timing cues (notably consonant voice onset time and vowel duration) were most affected. Conclusion: The results suggest that auditory pathway abnormality is a relatively common consequence of FRDA. Regular auditory evaluation should therefore be part of the management regime for all affected individuals. This assessment should include both ABR testing, which can provide insights into the degree to which auditory neural activity is disrupted, and some functional measure of hearing capacity such as speech perception assessment, which can quantify the disorder and provide a basis for intervention.

Auditory function in individuals within Leber’s hereditary optic neuropathy pedigrees

“…The precise mechanisms underlying this disruption are unknown, but the abnormal electrophysiological findings point to a disruption in the synchrony of neural firing which could, in turn, result in a time-smeared representation of the acoustic stimuli [7,11]. Auditory temporal processing deficits have not been reported previously in individuals with LHON, but disruption of temporal resolution is a consistent finding in subjects with AN [10,11] including those due to other forms of mitochondrial disorder [12].…”

“…Auditory neuropathy (due to other aetiologies) has been consistently shown to affect the neural representation of temporal cues [10,11] and hence, speech understanding, which is dependent on accurate perception of subtle timing differences between phonemes (speech sounds) [12]. To date, however, there has been no formal investigation of auditory temporal processing in listeners with LHON.…”

The Mitochondrial Connection in Auditory Neuropathy

“…sensory cells, including IHCs, OHCs, and supporting cells in the cochlea with severe loss of neurons in the spiral ganglion (SpG) [Hallpike et al, 1980;Spoendlin, 1974]. Recent psychoacoustic data by Rance et al [2010] expand upon these earlier findings and indicate that individuals with FA having desynchronized ABRs (a subgroup of those studied) also had reduced performances on gap detection, amplitude-modulation detection, and frequency discrimination tasks. While these temporal and spectral measures were correlated with performance decrements on open-set speech tests and their corresponding phonologic error patterns, caution should be exercised in interpreting these results.…”

“…intense noise exposure, drug-related otoxicity), large individual differences in test performance limit the generalizability of this concept for taxonomy purposes. Empirical evidence from tests using monosyllabic words (conducted either in quiet or in the presence of background noise) or synthetic sentences (under ipsilateral and contralateral competing message conditions) indicates that performances can range anywhere from normal to disproportionately poor [Butinar et al, 2007;Hood and Berlin, 2003;Rance et al, 2008Rance et al, , 2010Satya-Murti et al, 1979Starr et al, 1996;Zeng et al, 1999]. Abnormalities associated with the acoustic stapedius reflex (absence of response, elevated thresholds, or significant decay) and efferent system dysfunction [measured by otoacoustic emission (OAE) suppression paradigms] can also be manifest [Abdala et al, 2000;Berlin et al, 2005;SatyaMurti et al, 1980;Starr et al, 1991].…”

Hearing disorders in brainstem lesions

“…The only report on the prevalence of hearing loss in brainstem disorders corrected for age and sex is a retrospective study by Luxon (1980) from the National Hospital Queen Square, London. Luxon studied 309 patients with brainstem disorders examined from 1941 to 1976, and noted that 181 or 58.6% had objective evidence of hearing loss shown by pure-tone audiograms ( (Luxon, 1980;Nakashima et al, 1999) yielded fewer hearing abnormalities than prospective ones (Jerger and Jerger, 1974;Musiek and Pinheiro, 1987;van der Poel et al, 1988;Levine et al, 1994;Aharonson et al, 1998;Lee et al, 2002;Rance et al, 2010), an occurrence of 52.8% versus 65.8% respectively. However, these prospective studies were small and contained a selection bias, being limited to some diseases seen in specific referral centers.…”