Singapore Med J 2009; 50(9) : e324 Case Report Department of Otorhinolaryngology – Head & Neck Surgery, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, Kubang Kerian, Kota Bharu 16150, Malaysia Mohd Khairi MD, MMed Surgeon and Senior Lecturer Wan Zaharah AW, BSc Speech Pathologist School of Dental Sciences Normastura AR, MCommMed Senior Lecturer Correspondence to: Dr Mohd Khairi Md Daud Tel: (60) 9 766 4098 Fax: (60) 9 766 4093 Email: khairi@kck. usm.my Auditory neuropathy: three cases among a group with sensorineural hearing loss Mohd Khairi M D, Normastura A R, Wan Zaharah A W ABSTRACT The prevalence of auditory neuropathy is not known, although the majority of cases are felt to lie within the population of neonatal intensive care unit graduates. We report three cases of auditory neuropathy, out of 211 children with sensorineural hearing loss, seen at our audiology clinic from April 1, 1999 to December 31, 2003. Two patients did not have a risk factor for hearing impairment. Screening policies based solely on transient evoked otoacoustic emissions testing will not detect auditory neuropathy effectively, and may falsely reassure parents and professionals unaware of this condition. Keywords: auditory neuropathy, deafness, hearing loss, sensorineural hearing loss, transient evoked otoacoustic emissions Singapore Med J 2009; 50(9): e324-e325 INTRODUCTION The means of early identiication and diagnosis of hearing impairment in the neonatal population have formed the subject of numerous studies and investigations. Selection of an adequate and speciic screening protocol is dificult, and has been an issue of consideration in many centres. Transient evoked otoacoustic emissions (TEOAEs) ill most protocols as a noninvasive, time-saving, easy-to- apply and nearly 100% accurate method of screening the newborn. (1,2) However, by using this instrument alone as a screening tool, we will miss the patient with a retrocochlear lesion. Auditory neuropathy (AN) is a hearing disorder characterised by the lack of auditory brainstem responses (ABRs) but with normal otoacoustic emissions. The prevalence of the disease is not known, but the majority are felt to lie within the population of neonatal intensive care unit (NICU) graduates. (3) Therefore, ABR testing is used in combination with TEOAEs for screening at the NICUs in some centres. (4) Nevertheless, it is also possible for AN to occur in the general population. CASE REPORTS We reviewed the medical records of the children who had been referred to our audiology clinic for hearing problems and speech delays, from April 1, 1999 to December 31, 2003. Out of 211 children with sensorineural hearing loss, three of them had AN. In all three patients, TEOAEs were present but their ABR results showed profound hearing loss in both ears. Therefore, the prevalence of AN in a group of patients with sensorineural hearing loss was 1.42%. Only one child had a high risk factor for hearing impairment. This child had severe neonatal jaundice secondary to G6PD deiciency. He underwent exchange transfusion twice. Apart from his speech, he also had gross developmental delay, and could only walk with support at two and a half years of age. The other two patients had no risk factors for hearing impairment. Both of them, a Malay and a Chinese, had been referred to us because of speech delay. They were born full term via normal delivery and had normal motor developments. Assessment by the speech pathologist showed that all three patients had good detection skills, but very poor discrimination skills. DISCUSSION The prevalence of AN is not well established. We report three cases of AN in a group of patients who presented to our clinic with sensorineural hearing loss, giving an AN prevalence of 1.42%. Rance et al and Madden et al reported a higher prevalence of 11% and 5.1%, respectively, (5,6) while Berg et al found a much higher incidence of AN among the population at risk for hearing impairment at 24%. (7) In two other studies on hearing-impaired children, the incidences were 2.5% and 4.0%, respectively. (8,9) Two of our patients did not have risk factors for hearing impairment, while one had a history of severe neonatal jaundice. It is known that AN can occur in the general population although it is more common in the group of infants with high-risk factors for hearing impairment. Foerst et al found that out of 32 children with AN, ive did not have a high-risk factor for hearing impairment. (10) Hyperbilirubinaemia was the second commonest risk factor for AN (11 children) after prematurity with postpartal complications (15 children).