This is the first study investigating the prevalence of ear diseases among Chinese adolescents using a stratified sampling method. Although it is only a local and partial survey, the current situation of ear diseases among urban secondary school students in Northwest China can be extrapolated. This survey provides scientific evidence for China and other developing countries to develop adolescent HI prevention and control strategies.
The observation that 3.32% percent of students have some form of ear disease suggests an urgent need for otologic health care in adolescents. Many of the cases affected the external ear, including the accessory auricle, the congenital preauricular fistula, the external auditory canal stenosis, the otitis externa and the first branchial cleft fistula. Although external ear diseases usually do not cause direct hearing and balancing damage, they may place a child at risk for developing damage. Middle ear disease was represented mainly by chronic purulent otitis media and secretory otitis media. The small proportion (19.23%, 10/52) of middle ear diseases is probably ascribed to the extensive application of antibiotics and the decreased incidence of secretory otitis media with physical development. However, the excessive treatment of secretory otitis media may lead to tympanic sclerosis during childhood , and, in fact, we observed two cases of tympanic sclerosis in our study. Therefore, the long-term effects of treatment should be carefully considered when making a surgical decision. The low proportion of chronic purulent inflammation we observed was consistent with the survey by Zakzouk et al. , which showed a decrease in urban incidence of chronic suppurative otitis media (CSOM) over the past two decades. Nevertheless, we need to remain vigilant because of the severe extracranial and intracranial complications due to chronic purulent inflammation. The majority of people were not aware of these ear diseases. Therefore, it is important to put some effort into otologic health education among school students.
In this survey, the most common ear disease (44.23%, 23/52) was SHL caused by noise, drugs, heredity, CSOM, otosclerosis and unidentified factors. SHL can cause life-long and sometimes life-threatening difficulties and it can profoundly affect the ability to communicate as well as hinder education and employment. Therefore, education on ear health deserves more attention in schools.
Congenital ear disease accounts for 42.31% (22/52) of the ear diseases we observed. It causes concern not only because of the possible damage to hearing or balance, but also due to its heritability and association with hereditary diseases in other organs.
According to our survey, the percentage of ear disease among boys was significantly higher than that among girls. While this is consistent with a study from the Jiangsu Province of China , it is contrary to that of Shargorodsky, et al. in 2010 . The discrepancy may result from differences in the genetic backgrounds of the study populations or the increased difference in use of portable audio and gaming devices by boys compared to girls in China. HI didn't correlate with age in our study, which may be a result of the minimal age difference of the subjects.
The percentage of students with SHL did not differ among the students with elevated levels of academic stress. However, because 40.27% of the students reported experiencing at least mildly elevated levels of academic stress, schools and communities may want to address this issue. The percentage of SHL increased significantly among those students with insomnia. Because there is not enough evidence to decide the exact causality, further studies are necessary to determine the relationship between insomnia and SHL.
Among all causes of SHL, noise was the most common (60.87%, 12/23). With the economic development of China, industrial, transportation-related and entertainment-related noise pollution has become increasingly prominent. While a temporary threshold shift in noise induced hearing loss is reversible, it is difficult to stop the progression of the threshold shift from temporary to permanent. It was recently reported that 3.4% of female and 10.3% of male youths in the US used hearing-protection in 2005-2006 . However, the students in our study lacked awareness of hearing protection principles. Therefore, an important method for reducing HI is to provide hearing health care education and guide adolescents to use portable audio and gaming devices appropriately.
This study only investigated ear diseases among urban and suburban students, not rural students. Studies covering a more extensive and varied area are needed. In addition, otologic eikonic data, important for the etiological diagnosis of SHL, were not collected.
This study suggests that the education and popularization of hearing health knowledge among adolescents should be prioritized. Otologists should reinforce the prevention and rehabilitation of HI among young people while technical services and the appropriate help should be provided to people with hearing and speech disabilities. Cerumen impaction accounted for a significant proportion of ear problems. Although cerumen removal should be carried out in a hospital, non-medical cerumen removal was very common. This practice, and the excessive use of portable audio devices, are two examples of bad habits those should be corrected to avoid the potential risk of HI.