|Year : 2015 | Volume
| Issue : 4 | Page : 206-209
The pure tone audiogram assessment of the students of a special school for deaf in Kaduna
Iliyasu Yunusa Shuaibu1, Aminu Bakari1, Abdulazeez Ahmed2, Mohammed Aminu Usman1
1 Department of Surgery, ENT Unit, Ahmadu Bello University Teaching Hospital, Zaria, Nigeria
2 Department of ENT, Aminu Kano Teaching Hospital, Kano, Nigeria
|Date of Web Publication||21-Jan-2016|
Dr. Iliyasu Yunusa Shuaibu
Department of Surgery, ENT Unit, Ahmadu Bello University Teaching Hospital (ABUTH), Shika, Zaria
Source of Support: None, Conflict of Interest: None
Background: Hearing impairment in children is an important public health problem. Children with hearing impairment are educated in special schools (schools for the deaf) and in our locality all are assumed to be deaf without necessarily subjecting them to audiological evaluation in some cases. The objective of this study was to identify the cause of hearing impairment, type and degree of hearing loss, and use of hearing aids among students attending special schools for the deaf in Kaduna.
Patients and Methods: This was a cross-sectional study conducted over a period of 4 months between February and May, 2014. Students aged 7-18 years attending Kaduna State Special Education School for the deaf, Katsina road, and demonstration school for the deaf, Kawo Kaduna, were recruited for the study. A questionnaire investigating the student's biodata, causes of hearing impairment, and use of hearing aids was administered. This was followed by ear examination and pure tone audiometric tests. The data were analyzed using Statistical Package for the Social Science version 16.
Results: A total of 307 participants were recruited as the study group. Among them, 58.6% were males and 41.4% were females. The mean age of the study subjects was 13.5 ± 3.6 standard deviation (SD) years. Only 27.7% of the study population have a known cause of their hearing impairment. Two hundred and ninety seven (97.4%) of the students had sensorineural hearing loss, while out of the remaining subjects 5 (1.6%) have conductive and 3 (0.9%) have mixed hearing losses. Two hundred and sixty eight (87.3%) of the participants had profound hearing loss while 37 (12%) had mild-to-severe hearing loss. Two students (0.7%) were found to have normal hearing. No student was found to be using hearing aid.
Conclusion: In majority of the students, the cause of the hearing impairment is unknown. Some of the students have residual hearing and none of them is using hearing aids. Further evaluation and possible amplification may be required to rehabilitate some of these students into normal schools.
Keywords: Audiometry, schools for the deaf, deafness, hearing aid, hearing impairment
|How to cite this article:|
Shuaibu IY, Bakari A, Ahmed A, Usman MA. The pure tone audiogram assessment of the students of a special school for deaf in Kaduna. Arch Int Surg 2015;5:206-9
|How to cite this URL:|
Shuaibu IY, Bakari A, Ahmed A, Usman MA. The pure tone audiogram assessment of the students of a special school for deaf in Kaduna. Arch Int Surg [serial online] 2015 [cited 2019 Dec 15];5:206-9. Available from: http://www.archintsurg.org/text.asp?2015/5/4/206/174661
| Introduction|| |
Hearing impairment in children is a major public health problem in developing countries.  Deafness can affect communication and learning, and therefore hearing is necessary for the normal development and maturation of a child. A deaf child may be associated with poor speech development as he or she cannot hear.  Speech and hearing are closely integrated. Approximately, 1/1,000 live birth develop bilateral permanent childhood hearing impairment (PCHI).  This is defined as confirmed permanent bilateral hearing impairment exceeding 40 dBHL (hearing level) (average pure tone thresholds at 0.5 kHz, 1, 2 kHz, and 4 kHz) in the better hearing ear. ,
The World Health Organization (WHO) applies the term "deafness" to persons whose hearing loss is so severe that they cannot benefit from amplification.  This means that a deaf person is the one whose sense of hearing is nonfunctional for ordinary purpose of life, or whose hearing loss is greater than 91 dB (profound) or total deafness.  According to the WHO, hearing impairment is a dysfunction measureable in the laboratory or clinic, activity limitation is one of the auditory difficulties experienced by an individual and participation restriction is the nonauditory effect of these on their life.  In Nigeria today, there exist at least one school catering to the deaf in major cities, where they are educated separately.  Some of the famous schools for the deaf in Nigeria are as follows  : Wesley School for the deaf, Surulere, Lagos; Ibadan mission School for the deaf and Enugu Mission School for the deaf.
Ajavon et al. reported that all the children go to these schools are assumed to be deaf and the emphasis is placed on academic achievement and vocational training.  In Kaduna state, there are both government-owned and private schools for the deaf. Some of the students may not have undergone complete audiological evaluation prior to the admission into these schools. This may be due to the prevailing level of poverty as well as the lack of specialized center for screening and early identification of deaf children in the country. There have been very few studies conducted in Nigeria on pure tone audiogram assessment of children attending special school for the deaf. It is hoped that this study will add to the available knowledge by providing a documentary evidence for advocacy in terms of establishing protocols for enrolling children into schools for the deaf.
The aim of this study is to determine the cause, type and degree of hearing loss, and use of hearing aid among the students attending the special schools for the deaf in Kaduna.
| Patients and Methods|| |
This is a cross-sectional study carried out in Kaduna state special education school for the deaf and demonstration school for the deaf in Kaduna. It was conducted over a period of 4 months between February and May, 2014. Ethical approval was obtained from the Kaduna State Ministry of Health Ethical Review Committee and also from the school principals. Three hundred and seven (307) children 7-18 years of age formed the study population. An interviewer-based questionnaire was developed to capture the student's biodata, utilisation of hearing aid and other variables with the assistance of a teacher of the deaf (ToD)/sign language teacher. The cause of hearing impairment was retrieved from the student's record in the school. This was followed by otoscopy to visualize external auditory canal and tympanic membrane. Obstructing cerumen was removed using Jobson Horns probe and syringing before the pure tone audiometry (PTA). PTA was performed in a quiet office with ambient noise of 30dB, measured using a digital sound level meter TES1350A (TES electronics Taiwan). An audiometer AD 17 Kamplex electronics, Denmark was used to obtain values at frequencies of 0.5 kHz, 1.0 kHz, 2.0 kHz, 4.0 kHz, and 8 kHz. The average hearing level in the better ear was calculated using frequencies of 0.5 kHz, 1.0 kHz, 2.0 kHz, and 4.0 kHz. The hearing impairment was classified in accordance with the American Speech and Language Hearing Association  as normal, if the threshold level was less than 25 dBHL, mild if it was between 26 dBHL and 40 dBHL, moderate if it was between 41 dBHL and 55 dBHL, moderately severe if it was between 56 dBHL and 70 dBHL, severe if it was between 71 dBHL and 90 dBHL, and profound if it was 91 dBHL and above. The data were analyzed using Statistical Package for the Social Science (SPSS) version 16 (SPSS-Inc., Chicago, US).
| Results|| |
Three hundred and seven participants were recruited for the study, and there were 180 males (58.6%) and 127 females (41.4%) with an M:F ratio of 1.4:1. The age of the participants ranged from 7 years to 18 years, and the mean age was 13.5 years with a SD of ± 3.6. The age group with the highest number of participants was 15-18 years accounting for 139 (45.3%) participants. The age group with the lowest number was 7-9 years accounting for 75 (24.4%) participants as shown in [Table 1]. In majority of the students [227 (72.3%)], the cause of their hearing impairment was unknown. Infection related causes (comprising meningitis, measles, and other febrile illnesses) accounted for 63 (19.2%) cases, followed by ototoxicity with 21 (6.8%) cases as shown in [Figure 1].
|Figure 1: Distribution of causes of hearing impairment among the study population (N = 307)|
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Among these 307 students, 297 (97.4%) have sensorineural, 5 (1.6%) have conductive, and 3 (1%) have mixed hearing losses. All the types of hearing loss were more common among males compared to females as shown in [Table 2]. Using multivariate analysis, there was no statistically significant association between sex of the participants and the type of hearing loss [P > 0.05]. Two hundred and sixty eight (87.3%) of the participants have profound sensorineural hearing loss. The remaining 37 (12%) have hearing impairment ranging from mild to severe. Two of the students (0.7%) have normal hearing as shown in [Table 3]. None of the participants used hearing aids.
|Table 2: Distribution of types of hearing loss by sex among the study population (N = 305) |
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|Table 3: Distribution of degree of hearing loss among the study population by sex (N = 307) |
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| Discussion|| |
The study investigated the causes of hearing impairment, type and degree of hearing loss, and use of hearing aids by the participants. In this study, majority of the students attending the special schools for the deaf were male and this was in line with the findings of several other studies done locally and internationally. ,,,,, The high number of males may be due to sociocultural practices in some part of Northern Nigeria where only few girls have the privilege of acquiring Western education as most of them usually stay at home. It was also reported that in developing countries, children with hearing loss and deafness rarely receive any schooling.  As per this study, among the students attending the schools for the deaf the age group of 15-18 years had the highest number of participants. This is in line with the findings of Egeli et al.  The delay in enrolment at the school may be due to the lack of initial awareness, lack of trained hearing health-care personnel, and also lack of specialized centers for early identification and screening of deaf children in the country.
In this study, the cause of hearing impairment in majority of the study population [227 (71.8%)] is unknown with infection/febrile illnesses and ototoxicity accounting for 63 (19.9%) and 21 (6.6%) cases, respectively. This agrees with the findings by Egeli et al.  and Derekoy et al.  In most of the developing countries in Africa, including Nigeria, the cause of the deafness is usually unknown; probably congenital. , In the present study, the commonest type of hearing loss was sensorineural 297 (97.4%). This was consistent with the findings from similar studies by Christine et al.,  Ozturk et al.,  Nasser et al.  with 94%, 92.2%, and 98% respectively. Sensorineural hearing loss is the commonest type of hearing loss. This may be due to wide range of genetic, infectious, vascular, neoplastic, traumatic, toxic, iatrogenic, degenerative, immunologic, and inflammatory pathologies that can affect the cochlea.  It was reported that 10 out of every 1,000 children in USA have sensorineural hearing loss, and worldwide it occurs in 9-27 per 1,000 children. ,
In this study, profound hearing loss was found in up to 268 (87.3%) of the students while 39 (12%) have hearing impairment ranging from mild to severe. This is comparable to the findings of other studies in Nigeria,  Turkey,  and India.  However; it was in sharp contrast to the findings of some other authors , where the number of students with mild to severe hearing impairment was more than those with profound hearing loss in schools for the deaf. This may be due to lack of proper evaluation of the students before admission into these schools. Two participants were found to have normal hearing in this study. This was also the finding of a study done in Saudi Arabia.  This may be due to lack of proper evaluation before enrolment into the school. In this study no single student was found using hearing aids. This was also the findings of similar studies done locally. , This may be due to prevailing level of poverty in the community and the nonavailability of diagnostic facilities, services for fitting and maintaining hearing aids. According to the WHO fact sheet, production of hearing aids meets less than 10% of global need, and in developing countries fewer than 1 out of 40 people who need a hearing aid have one. 
| Conclusion|| |
The cause of deafness in majority of the students was unknown. Majority of the study population had sensorineural hearing loss, while 87.3% of the students are actually deaf, 12% have mild to severe hearing impairment. Incidentally, the remaining 2 (0.7%) participants had normal hearing. Students with hearing impairment ranging from mild to severe may benefit from hearing augmentation if further evaluated and can possibly be rehabilitated and reintegrated into normal schools.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]