The investigation of unilateral sensori-neural hearing loss

The site of the lesion in unilateral sensori-neural hearing loss (SNHL) may be confined to the receptor organ (labyrinthine) or may involve the auditory nerve including its central connections (retrolabyrinthine). The primary objective of the investigation of such a loss would be to define the probable site of the lesion. The protocol that we have found most productive and cost effective is as follows: 1. Audiometric evaluation consisting of a well masked pure tone audiogram, speech discrimination score and immitance studies. 2. Vestibular evaluation using photo-electric nystagmography and the Torok Monothermal Differential Caloric Test. Imaging studies of the temporal bone and brain are obtained on the basis of these tests. If the findings from auditory and vestibular tests are equivocal the patient is advised auditory brain stem response (ABR) testing. In our practice serologic tests for syphilis are obtained if there is the slightest suspicion of exposure. In this paper we report 2 cases which illustrate the value of our protocol and reliability of our technique.