The use of impedance measurements in the diagnosis of serious otitis media in a population of children
The development of equipment to measure impedance of the middle ear is discussed and the use of portable equipment in the identification of middle ear disorder. The pathology of the development of serous otitis media (SOM) is considered in relationship to its importance in children. The changes in the middle ear and possible sequelae of untreated cases is reviewed. A review of the current state of knowledge of SOM in children indicates that this could be a condition which is treated providing that a suitable programme of detection is available and the use of the impedance bridge in the community is discussed. A description of the pilot study when some 490 children were examined by the Author and had simultaneous tympanometry and audiometry sweep testing indicated that it was practical to carry out community studies. The pilot study highlighted the limitations of the current practice of sweep testing children at the age of school entrance as well as the limitations of otoscopy in relationship to impedance tympanometry. Associated factors in the clinical and social history were highlighted as well as a discussion of the sensitivity and specificity of the tests. As a result of the experience of the pilot study the Author was given a grant by the Regional Research Committee to study a population of children before, at and after school entrance. 1,000 children were selected from the Worcester and Malvern area and a staged programme developed. As a result of the programme some 23 cases were found to have SOM at operation. The individual cases are discussed and also the outcome in relationship to complications. One case of Cholesteatoma was also detected which had previously been unknown. The limitations of the programme developed are discussed as well as why cases were missed at the different phases of screening. As a result the thesis that impedance tympanometry can now be included in a hearing conservation programme is proposed and this should not, if properly organised, overload existing facilities. It could also be a more valuable procedure than the current practice of sweep testing audiometry. Other features of the programme include the apparent susceptibility of the first child in the family to persistent SOM. It is also clear that the staged programme can detect those cases of SOM which are not going to resolve spontaneously as it was found that cases missed at one phase probably persisted through to the next phase of the programme.