Mohd Khairi Md Daud

The effect of mild hearing loss on academic performance in primary school children

OBJECTIVES To determine the prevalence of mild hearing loss and its association with academic performance among primary school children. PATIENTS AND METHODS A comparative cross sectional study was conducted on standard (grade) five school children in a state in Malaysia. Five schools were selected by using simple random sampling. There were three classes (A, B and C) of standard five in each school. Students selection into these classes was made by respective school administration based on their final term examination in standard four. Class A was for the best academic achievers while class C was for the poorest. Ear examinations were done followed by pure tone audiometry for confirmation of the hearing status. In this study, mild hearing loss was defined as an average threshold of 20-39 dB at 0.5, 1, 2 and 4 kHz. Data analysis was done using SPSS Version 12.0 software. Chi-square test was used to determine the association between mild hearing loss and academic performance. The significant level was set at p=0.05. RESULTS From a total of 257 students, 234 have completed the examinations (response rate=91.0%). Fifty-three percent of them were boys while 47% were girls. A hundred and forty-nine (63.7%) of them were from class A while 85 (36.3%) were from class C. The prevalence of hearing loss in our school population was 15% (95% CI: 11.0-20.0%). Thirty-two (88.9%) of them were having conductive type. Out of the total, 38.9% were having problems in both ears. The students who have poor academic performance have been shown to be significantly associated with mild hearing loss (p<0.001). CONCLUSIONS There was a high prevalence of mild hearing loss among primary school children. This problem could affect their academic performance. Therefore, hearing assessment is highly recommended to be done on every child especially to those who have poor academic achievement.

Outcome of a newborn hearing screening program in a tertiary hospital in Malaysia: the first five years.

Background and Objective : Universal newborn hearing screening (UNHS) was started in the Hospital Universiti Sains Malaysia (HUSM) in January 2003. To comply with international standards, we determined the outcome of the newborn hearing screening program for the first 5 years of its implementation, from January 2003 to December 2007. Methods : The program screened all infants who were delivered in HUSM. In a retrospective review, the outcomes in terms of coverage, prevalence of hearing impairment, referral rate for each screening, age at detection of hearing impairment and at hearing aid-fitting were analyzed. Results : Ninety-eight percent of newborns were screened. The study included 16 100 randomly selected newborns. The initial screening referral rate was 25.5%. The prevalence of default for second and third screening was 33.9% and 40.7%, respectively. The mean (SD) age at detection of hearing impairment was 3.3 months (0.86). The mean (SD) age at fitting of a hearing aid was 13.6 (4.8) months.The prevalence of hearing impairment was 0.09%. Conclusion : A newborn hearing screening program is an important tool for early diagnosis and treatment. Even though the prevalence of hearing impairment may be low, the problem needs to be addressed early as the development of infants requires normal hearing.

Mutation detection in GJB2 gene among Malays with non-syndromic hearing loss

OBJECTIVES To identify the mutations in the GJB2 gene and to determine its association with non-syndromic hearing loss in Malays. METHODS A comparative cross sectional study was conducted on a group of children from the deaf schools and the normal schools. A total of 91 buccal cell samples of non-syndromic hearing loss and 91 normal hearing children were taken. Polymerase chain reaction was used to amplify the coding region of GJB2 gene. The PCR product of GJB2 coding region was preceded with screening for mutations using denaturing high performance liquid chromatography (dHPLC) and mutations detected were confirmed by DNA sequencing. RESULTS Twelve sequence variations including mutations and polymorphisms were found in 32 patients and 37 control subjects. The variations were G4D, V27I, E114G, T123N, V37I and R127H in both groups, W24X, R32H, 257_259 del CGC and M34L in patients only and I203T and V153I in control subjects only. There were no association between homozygous (P=0.368) or heterozygous (P=0.164) GJB2 gene and non-syndromic hearing loss. CONCLUSIONS The types of GJB2 gene mutation were different and vary in Malay non-syndromic hearing loss as compared to the other races. Furthermore, the mutation did not associate with hearing loss in the population. Other related genes are believed to be involved and need to be sought in this group of patients.

The performance of distortion product otoacoustic emissions and automated auditory brainstem response in the same ear of the babies in neonatal unit

OBJECTIVE To identify the outcomes of hearing screening using different protocols of both Distortion Product Otoacoustic Emissions (DPOAE) and Automated Auditory Brainstem Response (AABR) tests in the same ear of the babies in a neonatal unit population. METHODS A cross-sectional study was carried out on babies who were admitted into a neonatal unit. By using a formula of single proportion and considering 20% drop out, the number of sample required was 114. The subjects were chosen by using a systematic random sampling. The infants selected were subjected to DPOAE followed by AABR tests screening at the same setting before discharge. RESULTS There were 73 newborns (61.6% male and 38.4% female) participated in this study with a total of 146 ears screened. Ototoxic medication was the most common risk factor followed by hyperbilirubinaemia and low birth weight. AABR had higher passing rate (82.9%) as compared to DPOAE (77.4%). The highest passing rate was achieved if the protocol of either passed DPOAE or AABR was used (90.4%). The rate was lower when auditory neuropathy spectrum disorder (ANSD) has been considered (82.9%). Hyperbilirubinaemia, prematurity, craniofacial malformation and ototoxic drugs seem to be the high risk factors for auditory neuropathy. CONCLUSION AABR has a higher passing rate as compared to DPOAE. However, the use of both instruments in the screening process especially in NICU will be useful to determine the infants with ANSD who may need different approach to management. Therefore, a protocol in which newborns are tested with AABR first and then followed by DPOAE on those who fail the AABR is recommended.