Overview
Auditory neuropathy/ dys-synchrony/ peri-synaptic audiopathy (AN) are terms used to describe a specific hearing disorder with a disturbed auditory neural response in presence of normal cochlear function. Initially reported as early as the 1970s by ( Hinchcliffe et al) after observation of the patients with normal hearing thresholds, who had difficulty to detect the sounds especially in presence of background noise . Auditory Neuropathy is characterized by five integral features that distinguish it from other types of hearing loss. These are: Variable audiometric results anywhere from normal hearing to Sensorineural hearing loss of any degree up to profound hearing loss showing unusual audiometric pattern , Preserved outer hair cells (OHCs) responses such as otoacoustic emissions (OAEs) and/or cochlear microphonics (CM) , Altered neural processing such abnormal auditory brainstem responses (ABRs) with a reduced or absent wave V , Poor speech perception with poor speech recognition score that seems out of proportion compared to their pure-tone detection thresholds. , absent stapedial reflexes to the ipsilateral and contralateral tone at a 110-dB hearing level .
In 2008 it was found that AN does not represent a single disease entity but it is a heterogeneous disease category with a wide range of hearing loss types ,etiologies , age and clinical manifestations hence the adoption of the term auditory neuropathy spectrum disorder (ANSD) by an International Newborn Hearing Screening Conference held in Italy following a comprehensive study of newborn hearing test results.
The prevalence of ANSD is variable in published studies from (0.23 to 15%) among hearing impaired individuals . Regarding the underlying etiological factors, auditory neuropathy can be congenital or acquired . AN without the involvement of the neurological system has been termed as primary auditory neuropathy (PAN).
Peripheral neuropathy is not a constant finding in all patients with this hearing disorder , AN may occur in the afferent pathway of acoustic nerve, probably accompanied by the pathological changes of efferent nerve in the olivocochlear system inside the brainstem Our study is conducted to detect the prevalence of peripheral neuropathy among patients with auditory neuropathy spectrum disorder .
Eligibility
Inclusion Criteria:
- Age ranges from 12 to 50 years old.
- Disproportionate speech recognition score (SRS) with the hearing threshold level.
- The auditory brainstem response (ABR) test with no waveform or, disturbed waves or, detectable wave V at high intense stimulus.
- The otoacoustic emission (OAE) and/or cochlear microphonic (CM) potential may be present.
Exclusion Criteria:
- While the participants who have these criteria will be excluded from the study:
- Consistent SRS and ABR response with hearing threshold level.
- Abnormal finding in brain imaging.
- Patients with history of diabetes and/or other causes of peripheral neuropathy