Evaluation of special hearing tests in established central nervous system lesions

Abstract

The audiological signs of peripheral (Cochlear & neuronal) disorders are well established but those of the central lesions are not well accepted particularly it is true of our Indian populaion. Stevens (1974) suggested that for interpretation of the results of the tests for central auditory disorders, apart from the location and nature of the lesions, the age of the patient, his co-operation, and language proficiency are to be taken into consideration. In this background this study is undertaken to evaluate the performance of 91 cases of the known central nervous system disorders, with conventional and special tests for the retro-cochlear deafness. In later category filtered and staggered speech tests in Hindi were carried out. The results have been correlated with the parallel vestibular and neurological assessments. Total deafness due to very advanced and chronic lesions boldly limited the utility of any audiological test, a problem very special to our population. However, very good correlation was established in 34% cases having positive evidence of brainstem lesions with these special tests, in contrast to 60% cases having positive audiological signs compatable with supra-tentoreal lesions. Vestibular tests however, appear to provide a very valuable assistance in localisation of these central neuro-otological disorders.